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Rault LC, O'Neal ST, Johnson EJ, Anderson TD. Vaporous essential oil isolates enhance LLIN efficacy for pyrethroid-resistant mosquitoes. JOURNAL OF VECTOR ECOLOGY : JOURNAL OF THE SOCIETY FOR VECTOR ECOLOGY 2024; 49:S1-S4. [PMID: 39315962 DOI: 10.52707/1081-1710-49.2.s1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/25/2024]
Affiliation(s)
- Leslie C Rault
- Department of Entomology, University of Nebraska, Lincoln, NE, U.S.A
| | - Scott T O'Neal
- Department of Entomology, University of Nebraska, Lincoln, NE, U.S.A
| | - Ellis J Johnson
- Department of Entomology, University of Nebraska, Lincoln, NE, U.S.A
| | - Troy D Anderson
- Department of Entomology, University of Nebraska, Lincoln, NE, U.S.A.,
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Syme T, N’dombidjé B, Todjinou D, Ariori V, Ngufor C. Laboratory evaluation of the regeneration time, efficacy and wash-resistance of PermaNet Dual (a deltamethrin-chlorfenapyr net) against susceptible and pyrethroid-resistant strains of Anopheles gambiae sensu lato. PLoS One 2024; 19:e0298513. [PMID: 39208123 PMCID: PMC11361417 DOI: 10.1371/journal.pone.0298513] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2024] [Accepted: 06/19/2024] [Indexed: 09/04/2024] Open
Abstract
Pyrethroid-chlorfenapyr nets have been recommended for malaria control by the World Health Organisation (WHO) after an alpha-cypermethrin-chlorfenapyr net showed improved impact in epidemiological trials. PermaNet® Dual is a new deltamethrin-chlorfenapyr net developed by Vestergaard Sàrl to expand options to control programmes. A series of laboratory studies were performed according to WHO guidelines to assess the regeneration time, efficacy and wash-resistance of PermaNet® Dual. Regeneration time was determined by subjecting net pieces to cone bioassays and tunnel tests before and 0, 1, 2, 3, 5 and 7 days after washing. The wash-resistance of PermaNet® Dual was evaluated compared to WHO-prequalified pyrethroid-only (PermaNet® 2.0) and pyrethroid-chlorfenapyr (Interceptor® G2) nets by testing net pieces washed 0, 1, 3, 5, 10, 15 and 20 times in cone bioassays and tunnel tests. Tests were performed with susceptible and pyrethroid-resistant strains of Anopheles gambiae to assess the pyrethroid and chlorfenapyr components separately. Net pieces were also analysed to determine insecticide content. In regeneration time studies, the biological activity of the deltamethrin and chlorfenapyr components of PermaNet® Dual regenerated within one day after washing and a 1-day washing interval was adopted for wash-resistance studies. PermaNet® Dual induced high mortality (98%) and blood-feeding inhibition (98%) of the susceptible strain after 20 washes fulfilling WHO efficacy criteria in tunnel tests (≥80% mortality, ≥90% blood-feeding inhibition). Similar results were obtained with PermaNet® 2.0 (99% mortality, 99% blood-feeding inhibition) and Interceptor® G2 (99% mortality, 98% blood-feeding inhibition) washed 20 times. In wash-resistance tunnel tests against the pyrethroid-resistant strain, PermaNet® Dual washed 20 times induced high mortality (91%) and blood-feeding inhibition (73%), which was similar to Interceptor® G2 (87% mortality, 79% blood-feeding inhibition) and superior to PermaNet® 2.0 (47% mortality, 68% blood-feeding inhibition). PermaNet® Dual fulfilled WHO efficacy criteria in laboratory bioassays and showed potential to improve control of pyrethroid-resistant malaria vectors.
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Affiliation(s)
- Thomas Syme
- London School of Hygiene & Tropical Medicine, London, United Kingdom
- Centre de Recherche Entomologique de Cotonou, Cotonou, Benin
- Pan African Malaria Vector Research Consortium (PAMVERC), Cotonou, Benin
| | - Boris N’dombidjé
- Centre de Recherche Entomologique de Cotonou, Cotonou, Benin
- Pan African Malaria Vector Research Consortium (PAMVERC), Cotonou, Benin
| | - Damien Todjinou
- Centre de Recherche Entomologique de Cotonou, Cotonou, Benin
- Pan African Malaria Vector Research Consortium (PAMVERC), Cotonou, Benin
| | - Victoria Ariori
- Centre de Recherche Entomologique de Cotonou, Cotonou, Benin
- Pan African Malaria Vector Research Consortium (PAMVERC), Cotonou, Benin
| | - Corine Ngufor
- London School of Hygiene & Tropical Medicine, London, United Kingdom
- Centre de Recherche Entomologique de Cotonou, Cotonou, Benin
- Pan African Malaria Vector Research Consortium (PAMVERC), Cotonou, Benin
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Hayes CC, Schal C. Review on the impacts of indoor vector control on domiciliary pests: good intentions challenged by harsh realities. Proc Biol Sci 2024; 291:20240609. [PMID: 39043243 PMCID: PMC11265923 DOI: 10.1098/rspb.2024.0609] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2024] [Revised: 05/16/2024] [Accepted: 05/28/2024] [Indexed: 07/25/2024] Open
Abstract
Arthropod vectored diseases have been a major impediment to societal advancements globally. Strategies to mitigate transmission of these diseases include preventative care (e.g. vaccination), primary treatment and most notably, the suppression of vectors in both indoor and outdoor spaces. The outcomes of indoor vector control (IVC) strategies, such as long-lasting insecticide-treated nets (LLINs) and indoor residual sprays (IRSs), are heavily influenced by individual and community-level perceptions and acceptance. These perceptions, and therefore product acceptance, are largely influenced by the successful suppression of non-target nuisance pests such as bed bugs and cockroaches. Adoption and consistent use of LLINs and IRS is responsible for immense reductions in the prevalence and incidence of malaria. However, recent observations suggest that failed control of indoor pests, leading to product distrust and abandonment, may threaten vector control programme success and further derail already slowed progress towards malaria elimination. We review the evidence of the relationship between IVC and nuisance pests and discuss the dearth of research on this relationship. We make the case that the ancillary control of indoor nuisance and public health pests needs to be considered in the development and implementation of new technologies for malaria elimination.
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Affiliation(s)
- Christopher C. Hayes
- Department of Entomology and Plant Pathology, North Carolina State University, Campus Box 7613, Raleigh, NC27695-7613, USA
| | - Coby Schal
- Department of Entomology and Plant Pathology, North Carolina State University, Campus Box 7613, Raleigh, NC27695-7613, USA
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Nkahe DL, Kopya E, Ngangue Siewe NI, Ndjeunia Mbiakop P, Kala Chouakeu NA, Mimpfoundi R, Kekeunou S, Awono-Ambene P, Antonio-Nkondjio C. Durability of PBO nets (Olyset Plus®), 12 months after their distribution in Bertoua, Cameroon. Parasite Epidemiol Control 2024; 26:e00373. [PMID: 39228793 PMCID: PMC11369369 DOI: 10.1016/j.parepi.2024.e00373] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2023] [Revised: 05/06/2024] [Accepted: 07/28/2024] [Indexed: 09/05/2024] Open
Abstract
Background The rapid spread of pyrethroid resistance has led to a change in strategy, going from pyrethroid-based nets to PBO + pyrethroid-treated nets. Although these new nets may significantly improve the control of pyrethroid-resistant mosquitoes, their durability in the field remain not yet well documented. This study investigates the durability and washing resistance of Olyset-Plus nets in the city centre and rural areas of Bertoua, Cameroon. In each site, a semi-structured questionnaire was administered to at least 190 households with an Olyset-Plus net. Factors such as net use, physical integrity and bioefficacy were recorded. Bioassays were conducted on the collected nets to assess their bioefficacy and resistance to washing. They were tested against wild Anopheles gambiae sensus lato (s.l.). Unused nets and the Kisumu strain were used as controls. Washing and cone testing of the nets was carried out according to standard WHO protocols. Results A high rate of net use by children was recorded in the urban area (89.1% (106/119)) compared to the rural area (39.7% (118/297)). The majority of Olyset-Plus nets inspected 82.2% (162/197) in the rural area and 88% (206/234) in the urban centre were in good condition (Hole Index<64). Only 5.6% and 6.8% of nets were badly torn in rural and urban sites respectively. Nets were washed more regularly in the urban centre. 88.1% of urban dwellers reported having washed their nets at least once compared to only 62% of rural dwellers. Bioefficacy tests with nets indicated a mortality rate ranging from 66% for unwashed nets to 86.7% for nets washed at least once. Bioefficacy varied significantly in the city of Bertoua according to net washing frequency, soaking time, soap type and drying location, whereas in the rural village, only washing(washed or unwashed) and soaking status (soaked or unsoaked) significantly influenced the bioefficacy of Olyset-Plus nets. Conclusions This study revealed different handling practices of bed nets in rural and urban settings which could significantly affect Olyset-Plus nets bio-efficacy and durability. Routine monitoring and sensitization of communities to best practices concerning bed nets usage and handling during mass distribution might enhance the net durability in the community.
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Affiliation(s)
- Diane Leslie Nkahe
- Institut de Recherche de Yaoundé (IRY), Organisation de Coordination Pour la Lutte Contre les Endémies en Afrique Centrale (OCEAC), P.O. Box 288, Yaoundé, Cameroon
- Department of Animal Physiology and Biology, Faculty of Science, University of Yaoundé I, P.O. Box 337, Yaoundé, Cameroon
| | - Edmond Kopya
- Institut de Recherche de Yaoundé (IRY), Organisation de Coordination Pour la Lutte Contre les Endémies en Afrique Centrale (OCEAC), P.O. Box 288, Yaoundé, Cameroon
- Department of Animal Physiology and Biology, Faculty of Science, University of Yaoundé I, P.O. Box 337, Yaoundé, Cameroon
| | - Nasser Idriss Ngangue Siewe
- Institut de Recherche de Yaoundé (IRY), Organisation de Coordination Pour la Lutte Contre les Endémies en Afrique Centrale (OCEAC), P.O. Box 288, Yaoundé, Cameroon
- Department of Animal Physiology and Biology, Faculty of Science, University of Douala, B.P. 24157, Cameroon
| | - Paulette Ndjeunia Mbiakop
- Institut de Recherche de Yaoundé (IRY), Organisation de Coordination Pour la Lutte Contre les Endémies en Afrique Centrale (OCEAC), P.O. Box 288, Yaoundé, Cameroon
- Department of Animal Physiology and Biology, Faculty of Science, University of Yaoundé I, P.O. Box 337, Yaoundé, Cameroon
| | - Nelly Armanda Kala Chouakeu
- Institut de Recherche de Yaoundé (IRY), Organisation de Coordination Pour la Lutte Contre les Endémies en Afrique Centrale (OCEAC), P.O. Box 288, Yaoundé, Cameroon
- Vector-Borne Diseases Laboratory of the Research Unit of Biology and Applied Ecology (VBID-RUBAE), Department of Animal Biology, Faculty of Science, University of Dschang, Dschang, Cameroon
| | - Rémy Mimpfoundi
- Department of Animal Physiology and Biology, Faculty of Science, University of Yaoundé I, P.O. Box 337, Yaoundé, Cameroon
| | - Sévilor Kekeunou
- Department of Animal Physiology and Biology, Faculty of Science, University of Yaoundé I, P.O. Box 337, Yaoundé, Cameroon
| | - Parfait Awono-Ambene
- Institut de Recherche de Yaoundé (IRY), Organisation de Coordination Pour la Lutte Contre les Endémies en Afrique Centrale (OCEAC), P.O. Box 288, Yaoundé, Cameroon
| | - Christophe Antonio-Nkondjio
- Institut de Recherche de Yaoundé (IRY), Organisation de Coordination Pour la Lutte Contre les Endémies en Afrique Centrale (OCEAC), P.O. Box 288, Yaoundé, Cameroon
- Vector Biology Liverpool School of Tropical Medicine Pembroke Place, Liverpool L3 5QA, UK
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Zhang Y, He S, He C, Zhou L, Xu O, Qiao L, Chen B, Cao Y, He Z. AsOBP1 is required for bioallethrin repellency in the malaria vector mosquito Anopheles sinensis. INSECT SCIENCE 2024. [PMID: 38389031 DOI: 10.1111/1744-7917.13332] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/06/2023] [Revised: 12/31/2023] [Accepted: 01/06/2024] [Indexed: 02/24/2024]
Abstract
The use of insecticides, primarily pyrethroids, is a pivotal strategy for mosquito control globally. Bioallethrin, the first commercially available volatile pyrethroid, can elicit spatial (i.e., noncontact) repellency to mosquitoes through the coactivation of olfactory receptor neurons and sodium channels. However, the olfactory mechanism of the repellency elicited by bioallethrin in mosquitoes is still unclear. Here, we demonstrated the involvement of AsOBP1 in the bioallethrin repellency in Anopheles sinensis, one of the main vectors of vivax malaria in China and other Southeast Asian countries. The behavioral and electrophysiological analyses in AsOrco-/- mutant found that the spatial repellency elicited by bioallethrin depended on the odorant receptor (OR)-mediated olfactory pathway. Furthermore, the repellency was reduced in the AsOBP1-/- mutant and a pyrethroid-resistant strain, in which the expression of AsOBP1 was significantly decreased. Moreover, recombinant AsOBP1 protein bound to bioallethrin in an in vitro competition assay. These results indicate that activation of the AsOBP1-mediated olfactory pathway is an important component of bioallethrin repellency. Our research lays the foundation for further elucidation into the olfactory mechanism of bioallethrin repellency and the behavioral modifications of pyrethroid-resistant mosquitoes.
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Affiliation(s)
- Yongjie Zhang
- Chongqing Key Laboratory of Vector Insects, Institute of Entomology and Molecular Biology, Chongqing Normal University, Chongqing, China
| | - Shulin He
- Chongqing Key Laboratory of Vector Insects, Institute of Entomology and Molecular Biology, Chongqing Normal University, Chongqing, China
| | - Chengyin He
- Chongqing Key Laboratory of Vector Insects, Institute of Entomology and Molecular Biology, Chongqing Normal University, Chongqing, China
| | - Ling Zhou
- Chongqing Key Laboratory of Vector Insects, Institute of Entomology and Molecular Biology, Chongqing Normal University, Chongqing, China
| | - Ou Xu
- Chongqing Key Laboratory of Vector Insects, Institute of Entomology and Molecular Biology, Chongqing Normal University, Chongqing, China
| | - Liang Qiao
- Chongqing Key Laboratory of Vector Insects, Institute of Entomology and Molecular Biology, Chongqing Normal University, Chongqing, China
| | - Bin Chen
- Chongqing Key Laboratory of Vector Insects, Institute of Entomology and Molecular Biology, Chongqing Normal University, Chongqing, China
| | - Yueqing Cao
- College of Life Sciences, Chongqing University, Chongqing, China
| | - Zhengbo He
- Chongqing Key Laboratory of Vector Insects, Institute of Entomology and Molecular Biology, Chongqing Normal University, Chongqing, China
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Djènontin A, Alfa D, Bouraima A, Soares C, Dahounto A, Cornélie S, Egrot M, Damien G, Remoué F, Sagna AB, Moiroux N, Pennetier C. Durability of the deltamethrin-treated polypropylene long-lasting net LifeNet® in a pyrethroid resistance area in south western Benin: A phase III trial. PLoS One 2023; 18:e0291755. [PMID: 37729177 PMCID: PMC10511067 DOI: 10.1371/journal.pone.0291755] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2022] [Accepted: 09/05/2023] [Indexed: 09/22/2023] Open
Abstract
BACKGROUND Long-lasting insecticidal bed nets (LLINs) are a key measure for preventing malaria and their evaluation is coordinated by the World Health Organization Pesticide Evaluation Scheme (WHOPES). LifeNet® was granted WHOPES time-limited interim recommendation in 2011 after successful Phase I and Phase II evaluations. Here, we evaluated the durability and community acceptance of LifeNet® in a Phase III trial from June 2014 to June 2017 in Benin rural area. METHODS A prospective longitudinal, cluster-randomized, controlled trial with households as the unit of observation was designed to assess the performance of LifeNet® over a three-year period, using a WHOPES fully recommended LLIN (PermaNet® 2.0) as a positive control. The primary outcomes were the bioassay performance using WHO cone assays and tunnel tests, the insecticide content and physical integrity. RESULTS At baseline, 100% of LLINs were within the tolerance limits of their target deltamethrin concentrations. By 36 months only 17.3% of LifeNet® and 8.5% of PermaNet® LLINs still were within their target deltamethrin concentrations. Despite these low rates, 100% of both LLINs meet WHO efficacy criteria (≥ 80% mortality or ≥ 95% knockdown or tunnel test criteria of ≥ 80% mortality or ≥ 90% blood-feeding inhibition) after 36 months using WHO cone bio-assays and tunnel tests. The proportion of LLINs in good physical condition was 33% for LifeNet® and 29% for PermaNet® after 36 months. After 36 M the survivorship was 21% and 26% for LifeNet® and PermaNet® respectively. Although both LLINs were well accepted by the population, complaints of side effects were significantly higher among LifeNet® users than PermaNet® ones. CONCLUSION LifeNet® LLINs did meet WHO criteria for bio-efficacy throughout the study period and were well accepted by the population. This is an important step towards getting a full WHO recommendation for use in malaria endemic countries.
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Affiliation(s)
- Armel Djènontin
- Centre de Recherche Entomologique de Cotonou (CREC), Cotonou, Bénin
- Centre de Recherche Pour la Lutte Contre les Maladies Infectieuses Tropicales (CReMIT), Université D’Abomey-Calavi (UAC), Cotonou, Bénin
| | - Daleb Alfa
- Centre de Recherche Entomologique de Cotonou (CREC), Cotonou, Bénin
- Centre de Recherche Pour la Lutte Contre les Maladies Infectieuses Tropicales (CReMIT), Université D’Abomey-Calavi (UAC), Cotonou, Bénin
| | - Aziz Bouraima
- Centre de Recherche Entomologique de Cotonou (CREC), Cotonou, Bénin
- Centre de Recherche Pour la Lutte Contre les Maladies Infectieuses Tropicales (CReMIT), Université D’Abomey-Calavi (UAC), Cotonou, Bénin
| | - Christophe Soares
- Centre de Recherche Entomologique de Cotonou (CREC), Cotonou, Bénin
- Centre de Recherche Pour la Lutte Contre les Maladies Infectieuses Tropicales (CReMIT), Université D’Abomey-Calavi (UAC), Cotonou, Bénin
| | - Amal Dahounto
- Centre de Recherche Entomologique de Cotonou (CREC), Cotonou, Bénin
| | - Sylvie Cornélie
- Centre de Recherche Entomologique de Cotonou (CREC), Cotonou, Bénin
- MIVEGEC, Univ Montpellier, CNRS, IRD, Montpellier, France
| | - Marc Egrot
- Centre de Recherche Entomologique de Cotonou (CREC), Cotonou, Bénin
- MIVEGEC, Univ Montpellier, CNRS, IRD, Montpellier, France
| | - Georgia Damien
- Centre de Recherche Pour la Lutte Contre les Maladies Infectieuses Tropicales (CReMIT), Université D’Abomey-Calavi (UAC), Cotonou, Bénin
| | - Franck Remoué
- Centre de Recherche Entomologique de Cotonou (CREC), Cotonou, Bénin
- MIVEGEC, Univ Montpellier, CNRS, IRD, Montpellier, France
| | | | | | - Cédric Pennetier
- Centre de Recherche Entomologique de Cotonou (CREC), Cotonou, Bénin
- MIVEGEC, Univ Montpellier, CNRS, IRD, Montpellier, France
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Zoh MG, Bonneville JM, Laporte F, Tutagata J, Sadia CG, Fodjo BK, Mouhamadou CS, McBeath J, Schmitt F, Horstmann S, Reynaud S, David JP. Deltamethrin and transfluthrin select for distinct transcriptomic responses in the malaria vector Anopheles gambiae. Malar J 2023; 22:256. [PMID: 37667239 PMCID: PMC10476409 DOI: 10.1186/s12936-023-04673-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2023] [Accepted: 08/11/2023] [Indexed: 09/06/2023] Open
Abstract
BACKGROUND The widespread use of pyrethroid insecticides in Africa has led to the development of strong resistance in Anopheles mosquitoes. Introducing new active ingredients can contribute to overcome this phenomenon and ensure the effectiveness of vector control strategies. Transfluthrin is a polyfluorinated pyrethroid whose structural conformation was thought to prevent its metabolism by cytochrome P450 monooxygenases in malaria vectors, thus representing a potential alternative for managing P450-mediated resistance occurring in the field. In this study, a controlled selection was used to compare the dynamics of resistance between transfluthrin and the widely used pyrethroid deltamethrin in the mosquito Anopheles gambiae. Then, the associated molecular mechanisms were investigated using target-site mutation genotyping and RNA-seq. METHODS A field-derived line of An. gambiae carrying resistance alleles at low frequencies was used as starting material for a controlled selection experiment. Adult females were selected across 33 generations with deltamethrin or transfluthrin, resulting in three distinct lines: the Delta-R line (selected with deltamethrin), the Transflu-R line (selected with transfluthrin) and the Tiassale-S line (maintained without selection). Deltamethrin and transfluthrin resistance levels were monitored in each selected line throughout the selection process, as well as the frequency of the L1014F kdr mutation. At generation 17, cross-resistance to other public health insecticides was investigated and transcriptomes were sequenced to compare gene transcription variations and polymorphisms associated with adaptation to each insecticide. RESULTS A rapid increase in resistance to deltamethrin and transfluthrin was observed throughout the selection process in each selected line in association with an increased frequency of the L1014F kdr mutation. Transcriptomic data support a broader response to transfluthrin selection as compared to deltamethrin selection. For instance, multiple detoxification enzymes and cuticle proteins were specifically over-transcribed in the Transflu-R line including the known pyrethroid metabolizers CYP6M2, CYP9K1 and CYP6AA1 together with other genes previously associated with resistance in An. gambiae. CONCLUSION This study confirms that recurrent exposure of adult mosquitoes to pyrethroids in a public health context can rapidly select for various resistance mechanisms. In particular, it indicates that in addition to target site mutations, the polyfluorinated pyrethroid transfluthrin can select for a broad metabolic response, which includes some P450s previously associated to resistance to classical pyrethroids. This unexpected finding highlights the need for an in-depth study on the adaptive response of mosquitoes to newly introduced active ingredients in order to effectively guide and support decision-making programmes in malaria control.
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Affiliation(s)
- Marius Gonse Zoh
- Laboratoire d'Ecologie Alpine (LECA), Grenoble-Alpes University, Savoie Mont-Blanc University, CNRS, 38041, Grenoble, France.
- Vector Control Product Evaluation Centre (VCPEC) Institut Pierre Richet (VCPEC IPR)/INSP, Bouaké, Côte d'Ivoire.
| | - Jean-Marc Bonneville
- Laboratoire d'Ecologie Alpine (LECA), Grenoble-Alpes University, Savoie Mont-Blanc University, CNRS, 38041, Grenoble, France
| | - Frederic Laporte
- Laboratoire d'Ecologie Alpine (LECA), Grenoble-Alpes University, Savoie Mont-Blanc University, CNRS, 38041, Grenoble, France
| | - Jordan Tutagata
- Laboratoire d'Ecologie Alpine (LECA), Grenoble-Alpes University, Savoie Mont-Blanc University, CNRS, 38041, Grenoble, France
| | | | - Behi K Fodjo
- Centre Suisse de Recherches Scientifiques, Abidjan, Côte d'Ivoire
| | | | - Justin McBeath
- Envu, Milton Hall, Ely Road. Milton, Cambridge, CB24 6WZ, UK
| | - Frederic Schmitt
- Envu, 2022 Environmental Science FR S.A.S, 3 Place Giovanni Da Verrazzano, 69009, Lyon, France
| | - Sebastian Horstmann
- Envu, 2022 ES Deutschland GmbH, Alfred-Nobel-Straße 50, 40789, Monheim, Germany
| | - Stéphane Reynaud
- Laboratoire d'Ecologie Alpine (LECA), Grenoble-Alpes University, Savoie Mont-Blanc University, CNRS, 38041, Grenoble, France
| | - Jean-Philippe David
- Laboratoire d'Ecologie Alpine (LECA), Grenoble-Alpes University, Savoie Mont-Blanc University, CNRS, 38041, Grenoble, France
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Tchouakui M, Thiomela RF, Nchoutpouen E, Menze BD, Ndo C, Achu D, Tabue RN, Njiokou F, Joel A, Wondji CS. High efficacy of chlorfenapyr-based net Interceptor ® G2 against pyrethroid-resistant malaria vectors from Cameroon. Infect Dis Poverty 2023; 12:81. [PMID: 37641108 PMCID: PMC10463949 DOI: 10.1186/s40249-023-01132-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2023] [Accepted: 08/21/2023] [Indexed: 08/31/2023] Open
Abstract
BACKGROUND The increasing reports of resistance to pyrethroid insecticides associated with reduced efficacy of pyrethroid-only interventions highlight the urgency of introducing new non-pyrethroid-only control tools. Here, we investigated the performance of piperonyl-butoxide (PBO)-pyrethroid [Permanet 3.0 (P3.0)] and dual active ingredients (AI) nets [Interceptor G2 (IG2): containing pyrethroids and chlorfenapyr and Royal Guard (RG): containing pyrethroids and pyriproxyfen] compared to pyrethroid-only net Royal Sentry (RS) against pyrethroid-resistant malaria vectors in Cameroon. METHODS The efficacy of these tools was firstly evaluated on Anopheles gambiae s.l. and Anopheles funestus s.l. from Gounougou, Mibellon, Mangoum, Nkolondom, and Elende using cone/tunnel assays. In addition, experimental hut trials (EHT) were performed to evaluate the performance of unwashed and 20 times washed nets in semi-field conditions. Furthermore, pyrethroid-resistant markers were genotyped in dead vs alive, blood-fed vs unfed mosquitoes after exposure to the nets to evaluate the impact of these markers on net performance. The XLSTAT software was used to calculate the various entomological outcomes and the Chi-square test was used to compare the efficacy of various nets. The odds ratio and Fisher exact test were then used to establish the statistical significance of any association between insecticide resistance markers and bed net efficacy. RESULTS Interceptor G2 was the most effective net against wild pyrethroid-resistant An. funestus followed by Permanet 3.0. In EHT, this net induced up to 87.8% mortality [95% confidence interval (CI): 83.5-92.1%) and 55.6% (95% CI: 48.5-62.7%) after 20 washes whilst unwashed pyrethroid-only net (Royal Sentry) killed just 18.2% (95% CI: 13.4-22.9%) of host-seeking An. funestus. The unwashed Permanet 3.0 killed up to 53.8% (95% CI: 44.3-63.4%) of field-resistant mosquitoes and 47.2% (95% CI: 37.7-56.7%) when washed 20 times, and the Royal Guard 13.2% (95% CI: 9.0-17.3%) for unwashed net and 8.5% (95% CI: 5.7-11.4%) for the 20 washed net. Interceptor G2, Permanet 3.0, and Royal Guard provided better personal protection (blood-feeding inhibition 66.2%, 77.8%, and 92.8%, respectively) compared to pyrethroid-only net Royal Sentry (8.4%). Interestingly, a negative association was found between kdrw and the chlorfenapyr-based net Interceptor G2 (χ2 = 138; P < 0.0001) with homozygote-resistant mosquitoes predominantly found in the dead ones. CONCLUSIONS The high mortality recorded with Interceptor G2 against pyrethroid-resistant malaria vectors in this study provides first semi-field evidence of high efficacy against these major malaria vectors in Cameroon encouraging the implementation of this novel net for malaria control in the country. However, the performance of this net should be established in other locations and on other major malaria vectors before implementation at a large scale.
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Affiliation(s)
- Magellan Tchouakui
- Centre for Research in Infectious Diseases (CRID), P.O. Box 13501, Yaoundé, Cameroon.
| | - Riccado F Thiomela
- Centre for Research in Infectious Diseases (CRID), P.O. Box 13501, Yaoundé, Cameroon
- Department of Animal Biology and Physiology, Faculty of Science, University of Yaoundé 1, P.O. Box 812, Yaoundé, Cameroon
| | - Elysee Nchoutpouen
- Centre for Research in Infectious Diseases (CRID), P.O. Box 13501, Yaoundé, Cameroon
| | - Benjamin D Menze
- Centre for Research in Infectious Diseases (CRID), P.O. Box 13501, Yaoundé, Cameroon
| | - Cyrille Ndo
- Centre for Research in Infectious Diseases (CRID), P.O. Box 13501, Yaoundé, Cameroon
- Department of Biological Sciences, Faculty of Medicine and Pharmaceutical Sciences, University of Douala, P.O. Box 24157, Douala, Cameroon
| | - Dorothy Achu
- Ministry of Public Health, National Malaria Control Programme, P.O. Box 14386, Yaounde, Cameroon
| | - Raymond N Tabue
- Ministry of Public Health, National Malaria Control Programme, P.O. Box 14386, Yaounde, Cameroon
| | - Flobert Njiokou
- Department of Animal Biology and Physiology, Faculty of Science, University of Yaoundé 1, P.O. Box 812, Yaoundé, Cameroon
| | - Ateba Joel
- Ministry of Public Health, National Malaria Control Programme, P.O. Box 14386, Yaounde, Cameroon
| | - Charles S Wondji
- Centre for Research in Infectious Diseases (CRID), P.O. Box 13501, Yaoundé, Cameroon.
- Department of Vector Biology, Liverpool School of Tropical Medicine, Pembroke Place, Liverpool, L35QA, UK.
- International Institute of Tropical Agriculture (IITA), P.O. Box 2008, Yaoundé, Cameroon.
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9
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Kakati A, Banerjee A, Das P, Saha B, Goyary D, Karmakar S, Kishor S, Bhutia YD, Chattopadhyay P. Development of insecticide-impregnated polyester/cotton blend fabric and assessment of their repellent characteristics against Cimex lectularius and dengue vectors Aedes albopictus and Aedes aegypti. Parasit Vectors 2023; 16:122. [PMID: 37032336 PMCID: PMC10082990 DOI: 10.1186/s13071-023-05740-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2022] [Accepted: 03/15/2023] [Indexed: 04/11/2023] Open
Abstract
BACKGROUND Personal protection measures using insecticide-treated fabric is one of the most effective strategies to prevent the bites of hematophagous insects. Many countries have had success treating fabrics with pyrethroids on an individual level. METHODS In the current study, a new combination of insecticides, alpha-cypermethrin (ACP) and deltamethrin (DET), has been impregnated on fabric composed of a 50:50 blend of polyester and cotton. Residual and morphological analysis was performed along with the evaluation of physical parameters. Biological evaluations were performed to check the repellency, knockdown, and mortality of insecticide-impregnated fabric (IIF) against bed bugs (Cimex lectularius) using Petri plate assay and mosquitoes (Aedes aegypti and Aedes albopictus) using cone bioassay. RESULTS The results showed the repellency of IIF to be 56.6% for C. lectularius and a knockdown percentage of 53.3% and 63.3% for Ae. aegypti and Ae. albopictus, respectively. A > 80% mortality was found for both species of mosquitoes up to 20 cycles of washing with no significant difference (P > 0.05). From high-performance liquid chromatography (HPLC) analysis, the reduction in the contents of ACP and DET after subsequent washes can be correlated with the overall decrease in bioefficacy. ACP and DET remaining in unit gram of fabric after 20 wash cycles were found to be 5.4 mg and 3.1 mg, respectively. By examining the fabric's surface morphology using scanning electron microscope (SEM) and utilizing energy-dispersive x-ray (EDX) analysis, it was possible to identify the presence of insecticides that were adhered to the fabric. Differential scanning calorimetry (DSC) showed distinctive endothermic peak of insecticide at 98.3 ºC, whereas no change in thermal behavior was observed from thermo-gravimetric analysis (TGA). Furthermore, the physical attributes of IIF provide conclusive evidence for its firmness. CONCLUSION All experimental findings were consistent with the potential use of IIF as a bed bug- and mosquito-repellent fabric to be used against hematophagous infestations. This fabric can serve as a potential strategy to control vector-borne diseases like dengue, malaria, trench fever, etc.
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Affiliation(s)
- Ajay Kakati
- Division of Pharmaceutical Technology, Defence Research Laboratory (DRL), DRDO, Tezpur, 784001, Assam, India
| | - Amartya Banerjee
- Division of Pharmaceutical Technology, Defence Research Laboratory (DRL), DRDO, Tezpur, 784001, Assam, India
| | - Parikshit Das
- Division of Pharmaceutical Technology, Defence Research Laboratory (DRL), DRDO, Tezpur, 784001, Assam, India
| | - Buddhadeb Saha
- Division of Pharmaceutical Technology, Defence Research Laboratory (DRL), DRDO, Tezpur, 784001, Assam, India
| | - Danswrang Goyary
- Division of Pharmaceutical Technology, Defence Research Laboratory (DRL), DRDO, Tezpur, 784001, Assam, India
| | - Sanjeev Karmakar
- Division of Pharmaceutical Technology, Defence Research Laboratory (DRL), DRDO, Tezpur, 784001, Assam, India
| | - Sumit Kishor
- Division of Pharmaceutical Technology, Defence Research Laboratory (DRL), DRDO, Tezpur, 784001, Assam, India
| | - Yangchen D Bhutia
- Division of Pharmaceutical Technology, Defence Research Laboratory (DRL), DRDO, Tezpur, 784001, Assam, India
| | - Pronobesh Chattopadhyay
- Division of Pharmaceutical Technology, Defence Research Laboratory (DRL), DRDO, Tezpur, 784001, Assam, India.
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10
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Mbuba E, Odufuwa OG, Moore J, Mmbaga S, Tchicaya E, Edi C, Chalageri V, Uragayala S, Sharma A, Rahi M, Raghavendra K, Eapen A, Koenker H, Ross A, Moore SJ. Multi-country evaluation of the durability of pyrethroid plus piperonyl-butoxide insecticide-treated nets: study protocol. Malar J 2023; 22:30. [PMID: 36707886 PMCID: PMC9881340 DOI: 10.1186/s12936-023-04465-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2022] [Accepted: 01/20/2023] [Indexed: 01/29/2023] Open
Abstract
BACKGROUND Mass distributions of long-lasting insecticidal nets (LLINs) have contributed to large reductions in the malaria burden. However, this success is in jeopardy due in part to the increasing pyrethroid-resistant mosquito population as well as low LLINs coverage in various areas because the lifespan of LLINs is often shorter than the interval between replenishment campaigns. New insecticide-treated nets (ITNs) containing pyrethroid and piperonyl-butoxide (PBO) have shown a greater reduction in the incidence of malaria than pyrethroid LLINs in areas with pyrethroid-resistant mosquitoes. However, the durability (attrition, bio-efficacy, physical integrity and chemical retainment) of pyrethroid-PBO ITNs under operational settings has not been fully characterized. This study will measure the durability of pyrethroid-PBO ITNs to assess whether they meet the World Health Organization (WHO) three years of operational performance criteria required to be categorized as "long-lasting". METHODS A prospective household randomized controlled trial will be conducted simultaneously in Tanzania, India and Côte d'Ivoire to estimate the field durability of three pyrethroid-PBO ITNs (Veeralin®, Tsara® Boost, and Olyset® Plus) compared to a pyrethroid LLIN: MAGNet®. Durability monitoring will be conducted up to 36 months post-distribution and median survival in months will be calculated. The proportion of ITNs: (1) lost (attrition), (2) physical integrity, (3) resistance to damage score, (4) meeting WHO bio-efficacy (≥ 95% knockdown after 1 h or ≥ 80% mortality after 24 h for WHO cone bioassay, or ≥ 90% blood-feeding inhibition or ≥ 80% mortality after 24 h for WHO Tunnel tests) criteria against laboratory-reared resistant and susceptible mosquitoes, and insecticidal persistence over time will be estimated. The non-inferiority of Veeralin® and Tsara® Boost to the first-in-class, Olyset® Plus will additionally be assessed for mortality, and the equivalence of 20 times washed ITNs compared to field aged ITNs will be assessed for mortality and blood-feeding inhibition endpoints in the Ifakara Ambient Chamber Test, Tanzania. CONCLUSION This will be the first large-scale prospective household randomized controlled trial of pyrethroid-PBO ITNs in three different countries in East Africa, West Africa and South Asia, simultaneously. The study will generate information on the replenishment intervals for PBO nets.
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Affiliation(s)
- Emmanuel Mbuba
- Vector Control Product Testing Unit, Environmental Health and Ecological Science, Ifakara Health Institute, P.O. Box 74, Bagamoyo, Tanzania.
- Swiss Tropical and Public Health Institute, Kreuzstrasse 2, 4123, Allschwil, Switzerland.
- University of Basel, St. Petersplatz 1, 4002, Basel, Switzerland.
| | - Olukayode G Odufuwa
- Vector Control Product Testing Unit, Environmental Health and Ecological Science, Ifakara Health Institute, P.O. Box 74, Bagamoyo, Tanzania
- Swiss Tropical and Public Health Institute, Kreuzstrasse 2, 4123, Allschwil, Switzerland
- University of Basel, St. Petersplatz 1, 4002, Basel, Switzerland
- Epidemiology and Population Health Department, London School of Hygiene & Tropical Medicine, Keppel Street, London, WC1E 7HT, UK
| | - Jason Moore
- Vector Control Product Testing Unit, Environmental Health and Ecological Science, Ifakara Health Institute, P.O. Box 74, Bagamoyo, Tanzania
- Swiss Tropical and Public Health Institute, Kreuzstrasse 2, 4123, Allschwil, Switzerland
| | - Selemani Mmbaga
- Vector Control Product Testing Unit, Environmental Health and Ecological Science, Ifakara Health Institute, P.O. Box 74, Bagamoyo, Tanzania
| | - Emile Tchicaya
- Swiss Centre for Scientific Research in Côte d'Ivoire, 1303, Abidjan, Côte d'Ivoire
- Vegro Aps, Copenhagen, Denmark, Refshalevej 213A
| | - Constant Edi
- Swiss Centre for Scientific Research in Côte d'Ivoire, 1303, Abidjan, Côte d'Ivoire
| | - Vani Chalageri
- Field Unit, ICMR-National Institute of Malaria Research, Bangalore, Karnataka, India
| | - Sreehari Uragayala
- Field Unit, ICMR-National Institute of Malaria Research, Bangalore, Karnataka, India
| | - Amit Sharma
- ICMR-National Institute of Malaria Research, Sector-8, Dwarka, New Delhi, 110077, India
| | - Manju Rahi
- ICMR-Indian Council of Medical Research, Ansari Nagar, New Delhi, India
| | - Kamaraju Raghavendra
- ICMR-National Institute of Malaria Research, Sector-8, Dwarka, New Delhi, 110077, India
| | - Alex Eapen
- Field Unit, ICMR-Indian Council of Medical Research, Chennai, India
| | | | - Amanda Ross
- Swiss Tropical and Public Health Institute, Kreuzstrasse 2, 4123, Allschwil, Switzerland
- University of Basel, St. Petersplatz 1, 4002, Basel, Switzerland
| | - Sarah J Moore
- Vector Control Product Testing Unit, Environmental Health and Ecological Science, Ifakara Health Institute, P.O. Box 74, Bagamoyo, Tanzania
- Swiss Tropical and Public Health Institute, Kreuzstrasse 2, 4123, Allschwil, Switzerland
- University of Basel, St. Petersplatz 1, 4002, Basel, Switzerland
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11
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Orondo PW, Wang X, Lee MC, Nyanjom SG, Atieli H, Ondeto BM, Ochwedo KO, Omondi CJ, Otambo WO, Zhou G, Zhong D, Githeko AK, Kazura JW, Yan G. Habitat Diversity, Stability, and Productivity of Malaria Vectors in Irrigated and Nonirrigated Ecosystems in Western Kenya. JOURNAL OF MEDICAL ENTOMOLOGY 2023; 60:202-212. [PMID: 36334018 PMCID: PMC9835762 DOI: 10.1093/jme/tjac168] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/20/2022] [Indexed: 06/16/2023]
Abstract
Several sub-Saharan African countries rely on irrigation for food production. This study examined the impact of environmental modifications resulting from irrigation on the ecology of aquatic stages of malaria vectors in a semi-arid region of western Kenya. Mosquito larvae were collected from irrigated and non-irrigated ecosystems during seasonal cross-sectional and monthly longitudinal studies to assess habitat availability, stability, and productivity of anophelines in temporary, semipermanent, and permanent habitats during the dry and wet seasons. The duration of habitat stability was also compared between selected habitats. Emergence traps were used to determine the daily production of female adult mosquitoes from different habitat types. Malaria vectors were morphologically identified and sibling species subjected to molecular analysis. Data was statistically compared between the two ecosystems. After aggregating the data, the overall malaria vector productivity for habitats in the two ecosystems was estimated. Immatures of the malaria vector (Anopheles arabiensis) Patton (Diptera: Culicidae) comprised 98.3% of the Anopheles in both the irrigated and non-irrigated habitats. The irrigated ecosystem had the most habitats, higher larval densities, and produced 85.8% of emerged adult females. These results showed that irrigation provided conditions that increased habitat availability, stability, and diversity, consequently increasing the An. arabiensis production and potential risk of malaria transmission throughout the year. The irrigated ecosystems increased the number of habitats suitable for Anopheles breeding by about 3-fold compared to non-irrigated ecosystems. These results suggest that water management in the irrigation systems of western Kenya would serve as an effective method for malaria vector control.
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Affiliation(s)
- Pauline Winnie Orondo
- Department of Biochemistry, Jomo Kenyatta University of Agriculture and Technology, Nairobi, Kenya
- International Center of Excellence for Malaria Research, Tom Mboya University, College of Maseno University, Homa Bay, Kenya
| | - Xiaoming Wang
- Program in Public Health, College of Health Sciences, University of California at Irvine, Irvine, CA, USA
| | - Ming-Chieh Lee
- Program in Public Health, College of Health Sciences, University of California at Irvine, Irvine, CA, USA
| | - Steven G Nyanjom
- Department of Biochemistry, Jomo Kenyatta University of Agriculture and Technology, Nairobi, Kenya
| | - Harrysone Atieli
- International Center of Excellence for Malaria Research, Tom Mboya University, College of Maseno University, Homa Bay, Kenya
| | - Benyl M Ondeto
- International Center of Excellence for Malaria Research, Tom Mboya University, College of Maseno University, Homa Bay, Kenya
| | - Kevin O Ochwedo
- International Center of Excellence for Malaria Research, Tom Mboya University, College of Maseno University, Homa Bay, Kenya
| | - Collince J Omondi
- International Center of Excellence for Malaria Research, Tom Mboya University, College of Maseno University, Homa Bay, Kenya
| | | | - Guofa Zhou
- Program in Public Health, College of Health Sciences, University of California at Irvine, Irvine, CA, USA
| | - Daibin Zhong
- Program in Public Health, College of Health Sciences, University of California at Irvine, Irvine, CA, USA
| | - Andrew K Githeko
- Centre for Global Health Research, Kenya Medical Research Institute, Kisumu, Kenya
| | - James W Kazura
- Center for Global Health & Diseases, School of Medicine, Case Western Reserve University, Cleveland, OH, USA
| | - Guiyun Yan
- Program in Public Health, College of Health Sciences, University of California at Irvine, Irvine, CA, USA
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12
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Azizi S, Matowo J, Mbewe NJ, Protopopoff N, Athumani R, Matiku W, Shayo M, Tenu F, Rowland M, Mosha F, Kitau J. Laboratory and semi-field efficacy evaluation of permethrin-piperonyl butoxide treated blankets against pyrethroid-resistant malaria vectors. Sci Rep 2022; 12:22166. [PMID: 36550139 PMCID: PMC9774072 DOI: 10.1038/s41598-022-26804-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2022] [Accepted: 12/20/2022] [Indexed: 12/24/2022] Open
Abstract
To control pyrethroid-resistant malaria vectors, Indoor Residual Spraying (IRS) and Long-Lasting Insecticidal Nets (LLINs) that include additional ingredients to pyrethroid are being developed. Same progress needs to be made to the pyrethroid-treated blankets, which are more compatible with shelter structures found in emergency settings such as displaced populations. In the current study, efficacy of blankets treated with permethrin and piperonyl butoxide (PBO) was evaluated against pyrethroid-resistant Anopheles gambiae sensu stricto. Efficacy was compared with that of Olyset LLIN, Olyset Plus LLIN and untreated blanket in terms of mortality and blood-feeding inhibition against pyrethroid-resistant Anopheles gambiae mosquitoes. The current study indicates that, in emergency shelters such as migrant and refugee camps where LLINs cannot be used, PBO-permethrin blankets may provide protection against resistant mosquitoes if widely used. No side effects related to the use of the treated blankets were reported from the participants. These results need validation in a large-scale field trial to assess the epidemiological impact of the intervention, durability and acceptability of this new vector control strategy for malaria vector control.
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Affiliation(s)
- Salum Azizi
- Department of Medical Parasitology and Entomology, Kilimanjaro Christian Medical University College (KCMUCo), Moshi, Tanzania.
- Pan African Malaria Vector Research Consortium (PAMVERC), Moshi, Tanzania.
| | - Johnson Matowo
- Department of Medical Parasitology and Entomology, Kilimanjaro Christian Medical University College (KCMUCo), Moshi, Tanzania
- Pan African Malaria Vector Research Consortium (PAMVERC), Moshi, Tanzania
| | - Njelembo Joshua Mbewe
- Pan African Malaria Vector Research Consortium (PAMVERC), Moshi, Tanzania
- Department of Disease Control, London School of Hygiene and Tropical Medicine (LSHTM), London, WC1E 7HT, UK
| | - Natacha Protopopoff
- Pan African Malaria Vector Research Consortium (PAMVERC), Moshi, Tanzania
- Department of Disease Control, London School of Hygiene and Tropical Medicine (LSHTM), London, WC1E 7HT, UK
| | - Rashid Athumani
- Department of Medical Parasitology and Entomology, Kilimanjaro Christian Medical University College (KCMUCo), Moshi, Tanzania
- Pan African Malaria Vector Research Consortium (PAMVERC), Moshi, Tanzania
| | - Wambura Matiku
- Department of Medical Parasitology and Entomology, Kilimanjaro Christian Medical University College (KCMUCo), Moshi, Tanzania
- Pan African Malaria Vector Research Consortium (PAMVERC), Moshi, Tanzania
| | - Magreth Shayo
- Department of Medical Parasitology and Entomology, Kilimanjaro Christian Medical University College (KCMUCo), Moshi, Tanzania
- Pan African Malaria Vector Research Consortium (PAMVERC), Moshi, Tanzania
| | - Filemoni Tenu
- Department of Medical Parasitology and Entomology, Kilimanjaro Christian Medical University College (KCMUCo), Moshi, Tanzania
- Pan African Malaria Vector Research Consortium (PAMVERC), Moshi, Tanzania
| | - Mark Rowland
- Pan African Malaria Vector Research Consortium (PAMVERC), Moshi, Tanzania
- Department of Disease Control, London School of Hygiene and Tropical Medicine (LSHTM), London, WC1E 7HT, UK
| | - Franklin Mosha
- Department of Medical Parasitology and Entomology, Kilimanjaro Christian Medical University College (KCMUCo), Moshi, Tanzania
- Pan African Malaria Vector Research Consortium (PAMVERC), Moshi, Tanzania
| | - Jovin Kitau
- Department of Medical Parasitology and Entomology, Kilimanjaro Christian Medical University College (KCMUCo), Moshi, Tanzania
- World Health Organization, Country Office, P.O. Box 9292, Dar es Salaam, Tanzania
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13
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Pusawang K, Sattabongkot J, Saingamsook J, Zhong D, Yan G, Somboon P, Wongpalee SP, Cui L, Saeung A, Sriwichai P. Insecticide Susceptibility Status of Anopheles and Aedes Mosquitoes in Malaria and Dengue Endemic Areas, Thai-Myanmar Border. INSECTS 2022; 13:1035. [PMID: 36354859 PMCID: PMC9694411 DOI: 10.3390/insects13111035] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/10/2022] [Revised: 11/05/2022] [Accepted: 11/07/2022] [Indexed: 06/16/2023]
Abstract
The occurrence and spread of insecticide resistance has had a negative effect on the efficacy of insecticide-based tools and is distributed worldwide, including the Greater Mekong Subregion (GMS). This study aims to determine the insecticide susceptibility of malaria and dengue vectors in malaria and dengue hotspots on the Thai-Myanmar border. Mosquito larvae and pupae were obtained from water sources from December 2019 to April 2020 in Tha Song Yang District, Tak province, western Thailand. WHO bioassay susceptibility tests were conducted with three classes of insecticides to evaluate the knockdown and mortality rates of Anopheles and Aedes aegypti female adults. V1016G and F1534C kdr mutations in the voltage-gated sodium channel of Ae. aegypti were identified using a multiplex PCR. A total of 5764 female mosquitoes were bioassayed in this study, including Anopheles spp. (92.63%) and F1 Ae. aegypti (7.37%). After 24 h of observation, An. minimus s.l. (n = 3885) and An. maculatus s.l. (n = 1138) in Suan Oi (SO) and Tala Oka (TO) were susceptible to pyrethroids, organophosphates and carbamates (except bendiocarb) with 98-100% mortality (MR). Resistance to bendiocarb was detected with a mortality rate of 88.80%, 88.77%, and 89.92% for An. minimus s.l. (n = 125, 125) and An. maculatus s.l. (n = 66), respectively. The first generation of Ae. aegypti adult females were suspected of resistance to deltamethrin (n = 225, MR = 96.89%) and confirmed resistance to permethrin (n = 200, MR = 20.00%). V1016G and F1534C mutations were detected in three genotypes, heterozygote and homozygote forms. The correlation between the kdr alleles and deltamethrin resistance was significant. In conclusion, bendiocarb resistance was found in primary malaria vectors, An. minimus s.l. and An. maculatus s.l. F1 Ae. aegypti population was pyrethroids-resistant, associated with kdr alleles. Therefore, molecular analysis should be conducted to gain insights into the mechanism of insecticide resistance. Routine malaria vector control programmes, such as fogging implementation in hotspot villages to induce Aedes resistance available in peri-domestic sites, are questionable.
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Affiliation(s)
- Kanchon Pusawang
- Center of Insect Vector Study, Department of Parasitology, Faculty of Medicine, Chiang Mai University, Chiang Mai 50200, Thailand
| | - Jetsumon Sattabongkot
- Mahidol Vivax Research Center, Faculty of Tropical Medicine, Mahidol University, Bangkok 10400, Thailand
| | - Jassada Saingamsook
- Center of Insect Vector Study, Department of Parasitology, Faculty of Medicine, Chiang Mai University, Chiang Mai 50200, Thailand
| | - Daibin Zhong
- Department of Population Health and Disease Prevention, University of California, Irvine, CA 92697, USA
| | - Guiyun Yan
- Department of Population Health and Disease Prevention, University of California, Irvine, CA 92697, USA
| | - Pradya Somboon
- Center of Insect Vector Study, Department of Parasitology, Faculty of Medicine, Chiang Mai University, Chiang Mai 50200, Thailand
| | - Somsakul Pop Wongpalee
- Department of Microbiology, Faculty of Medicine, Chiang Mai University, Chiang Mai 50200, Thailand
| | - Liwang Cui
- Division of Infectious Diseases, Department of Internal Medicine, Morsani College of Medicine, University of South Florida, Tampa, FL 33612, USA
| | - Atiporn Saeung
- Center of Insect Vector Study, Department of Parasitology, Faculty of Medicine, Chiang Mai University, Chiang Mai 50200, Thailand
| | - Patchara Sriwichai
- Department of Medical Entomology, Faculty of Tropical Medicine, Mahidol University, Bangkok 10400, Thailand
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14
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Shawer R, El-Leithy ES, Abdel-Rashid RS, Eltaweil AS, Baeshen RS, Mori N. Preparation of Lambda-Cyhalothrin-Loaded Chitosan Nanoparticles and Their Bioactivity against Drosophila suzukii. NANOMATERIALS (BASEL, SWITZERLAND) 2022; 12:3110. [PMID: 36144898 PMCID: PMC9503733 DOI: 10.3390/nano12183110] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/20/2022] [Revised: 08/31/2022] [Accepted: 09/01/2022] [Indexed: 06/16/2023]
Abstract
The encapsulation of pesticides within nanoparticles is a promising approach of advanced technology in sustainable agriculture. Lambda-cyhalothrin (LC) was encapsulated by the ionotropic gelation technique into chitosan (CS)/tripolyphosphate (TPP) and CS/alginate (ALG) matrixes. CS-LC nanoparticles were characterized, and their efficacy was then evaluated against the key pest of soft fruits in Europe and the United States, Drosophila suzukii. The encapsulation efficiency (74%), nanoparticle yield (80%), polydispersity index (0.341), zeta potential (-23.1 mV) and particle size (278 nm) were determined at the optimum conditions. FTIR confirmed the cross-linkage between CS and TPP/ALG in the nanoparticles. The optimum formula recommended by the fractional factorial design was associated with the formulation variables of CS of high or low molecular weight, cross-linking agent (TPP), LC concentration (1.5% w/v) and stirring rate (1500 rpm), showing the highest desirability value (0.5511). CS-LC nanoparticles of the lowest particle size (278 nm) exhibited the highest percent mortality of D. suzukii males (86%) and females (84%), exceeding that caused by the commercial product (Karate-zeon® 10% CS) at 2 HAT. This is the first work to use the ionic gelation technique to make LC nanoparticles, to the best of our knowledge. The encapsulation of chemical pesticides within biodegradable polymeric nanoparticles could be helpful for establishing a sustainable IPM strategy with benefits for human and environmental health and the lifetime of pesticides.
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Affiliation(s)
- Rady Shawer
- Department of Plant Protection, Faculty of Agriculture (Saba Basha), Alexandria University, Alexandria 21531, Egypt
| | - Eman S. El-Leithy
- Department of Pharmaceutics and Industrial Pharmacy, Faculty of Pharmacy, October University for Modern Sciences and Arts (MSA), Cairo 12451, Egypt
- Department of Pharmaceutics and Industrial Pharmacy, Faculty of Pharmacy, Helwan University, Cairo 11795, Egypt
| | - Rania S. Abdel-Rashid
- Department of Pharmaceutics and Industrial Pharmacy, Faculty of Pharmacy, Helwan University, Cairo 11795, Egypt
| | - Abdelazeem S. Eltaweil
- Department of Chemistry, Faculty of Sciences, Alexandria University, Alexandria 21526, Egypt
| | - Rowida S. Baeshen
- Department of Biology, Faculty of Science, Tabuk University, Tabuk 71421, Saudi Arabia
| | - Nicola Mori
- Department of Biotechnology, Verona University, 37134 Verona, Italy
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15
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Ngangue-Siewe IN, Ndjeunia-Mbiakop P, Kala-Chouakeu NA, Bamou R, Talipouo A, Djamouko-Djonkam L, Vontas J, Mavridis K, Tombi J, Tchuinkam T, Mbida-Mbida JA, Antonio-Nkondjio C. Bendiocarb and Malathion Resistance in Two Major Malaria Vector Populations in Cameroon Is Associated with High Frequency of the G119S Mutation (Ace-1) and Overexpression of Detoxification Genes. Pathogens 2022; 11:pathogens11080824. [PMID: 35894047 PMCID: PMC9330212 DOI: 10.3390/pathogens11080824] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2022] [Revised: 07/19/2022] [Accepted: 07/21/2022] [Indexed: 12/10/2022] Open
Abstract
The spread of pyrethroid resistance in malaria vectors is a major threat affecting the performance of current control measures. However, there is still not enough information on the resistance profile of mosquitoes to carbamates and organophosphates which could be used as alternatives. The present study assessed the resistance profile of Anopheles gambiae s.l. to bendiocarb and malathion, at the phenotypic and molecular levels, in different eco-epidemiological settings in Cameroon. Anopheles gambiae s.l. mosquitoes were collected from four eco-epidemiological settings across the country and their susceptibility level to bendiocarb and malathion was determined using WHO tubes bioassays. The ace-1 target site G119S mutation was screened by PCR. Reverse Transcription quantitative PCR 3-plex TaqMan assays were used to quantify the level of expression of eight genes associated with metabolic resistance. Resistance to malathion and/or bendiocarb was recorded in all study sites except in mosquitoes collected in Kaélé and Njombé. The Ace-1 (G119S) mutation was detected in high frequencies (>40%) in Kékem and Santchou. Both An. gambiae and An. coluzzii were detected carrying this mutation. The cytochrome P450s gene Cyp6p3 associated with carbamate resistance and the glutathione S-transferase gene Gste2 associated with organophosphate resistance were found to be overexpressed. Genes associated with pyrethroid (Cyp6m2, Cyp9k1, Cyp6p3) and organochlorine (Gste2, Cyp6z1, Cyp6m2) and cuticle resistance (Cyp4g16) were also overexpressed. The rapid spread of resistance to organophosphates and carbamates could seriously compromise future control strategies based on IRS. It is therefore becoming important to assess the magnitude of bendiocarb and malathion resistance countrywide.
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Affiliation(s)
- Idriss Nasser Ngangue-Siewe
- Laboratory of Animal Biology and Physiology, University of Douala, Douala P.O. Box 24157, Cameroon; (I.N.N.-S.); (J.A.M.-M.)
- Laboratoire de Recherche sur le Paludisme, Organisation de Coordination pour la lutte contre les Endémies en Afrique Centrale (OCEAC), Yaoundé P.O. Box 288, Cameroon; (P.N.-M.); (N.A.K.-C.); (R.B.); (A.T.); (L.D.-D.)
| | - Paulette Ndjeunia-Mbiakop
- Laboratoire de Recherche sur le Paludisme, Organisation de Coordination pour la lutte contre les Endémies en Afrique Centrale (OCEAC), Yaoundé P.O. Box 288, Cameroon; (P.N.-M.); (N.A.K.-C.); (R.B.); (A.T.); (L.D.-D.)
- Faculty of Sciences, University of Yaoundé I, Yaoundé P.O. Box 812, Cameroon;
| | - Nelly Armanda Kala-Chouakeu
- Laboratoire de Recherche sur le Paludisme, Organisation de Coordination pour la lutte contre les Endémies en Afrique Centrale (OCEAC), Yaoundé P.O. Box 288, Cameroon; (P.N.-M.); (N.A.K.-C.); (R.B.); (A.T.); (L.D.-D.)
- Vector-Borne Diseases Laboratory of the Applied Biology and Ecology Research Unit (VBID-URBEA), Department of Animal Biology, Faculty of Science of the University of Dschang, Dschang P.O. Box 067, Cameroon;
| | - Roland Bamou
- Laboratoire de Recherche sur le Paludisme, Organisation de Coordination pour la lutte contre les Endémies en Afrique Centrale (OCEAC), Yaoundé P.O. Box 288, Cameroon; (P.N.-M.); (N.A.K.-C.); (R.B.); (A.T.); (L.D.-D.)
- Vector-Borne Diseases Laboratory of the Applied Biology and Ecology Research Unit (VBID-URBEA), Department of Animal Biology, Faculty of Science of the University of Dschang, Dschang P.O. Box 067, Cameroon;
| | - Abdou Talipouo
- Laboratoire de Recherche sur le Paludisme, Organisation de Coordination pour la lutte contre les Endémies en Afrique Centrale (OCEAC), Yaoundé P.O. Box 288, Cameroon; (P.N.-M.); (N.A.K.-C.); (R.B.); (A.T.); (L.D.-D.)
- Faculty of Sciences, University of Yaoundé I, Yaoundé P.O. Box 812, Cameroon;
| | - Landre Djamouko-Djonkam
- Laboratoire de Recherche sur le Paludisme, Organisation de Coordination pour la lutte contre les Endémies en Afrique Centrale (OCEAC), Yaoundé P.O. Box 288, Cameroon; (P.N.-M.); (N.A.K.-C.); (R.B.); (A.T.); (L.D.-D.)
- Vector-Borne Diseases Laboratory of the Applied Biology and Ecology Research Unit (VBID-URBEA), Department of Animal Biology, Faculty of Science of the University of Dschang, Dschang P.O. Box 067, Cameroon;
| | - John Vontas
- Institute of Molecular Biology and Biotechnology, Foundation for Research and Technology-Hellas, 70013 Heraklion, Greece; (J.V.); (K.M.)
- Pesticide Science Laboratory, Department of Crop Science, Agricultural University of Athens, 11855 Athens, Greece
| | - Konstantinos Mavridis
- Institute of Molecular Biology and Biotechnology, Foundation for Research and Technology-Hellas, 70013 Heraklion, Greece; (J.V.); (K.M.)
| | - Jeannette Tombi
- Faculty of Sciences, University of Yaoundé I, Yaoundé P.O. Box 812, Cameroon;
| | - Timoléon Tchuinkam
- Vector-Borne Diseases Laboratory of the Applied Biology and Ecology Research Unit (VBID-URBEA), Department of Animal Biology, Faculty of Science of the University of Dschang, Dschang P.O. Box 067, Cameroon;
| | - Jean Arthur Mbida-Mbida
- Laboratory of Animal Biology and Physiology, University of Douala, Douala P.O. Box 24157, Cameroon; (I.N.N.-S.); (J.A.M.-M.)
| | - Christophe Antonio-Nkondjio
- Laboratoire de Recherche sur le Paludisme, Organisation de Coordination pour la lutte contre les Endémies en Afrique Centrale (OCEAC), Yaoundé P.O. Box 288, Cameroon; (P.N.-M.); (N.A.K.-C.); (R.B.); (A.T.); (L.D.-D.)
- Vector Biology, Liverpool School of Tropical Medicine, Pembroke Place, Liverpool L3 5QA, UK
- Correspondence: ; Tel.: +237-699-53-86-56
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16
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Zoh MG, Tutagata J, Fodjo BK, Mouhamadou CS, Sadia CG, McBeath J, Schmitt F, Horstmann S, David JP, Reynaud S. Exposure of Anopheles gambiae larvae to a sub-lethal dose of an agrochemical mixture induces tolerance to adulticides used in vector control management. AQUATIC TOXICOLOGY (AMSTERDAM, NETHERLANDS) 2022; 248:106181. [PMID: 35504174 DOI: 10.1016/j.aquatox.2022.106181] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/03/2021] [Revised: 04/19/2022] [Accepted: 04/24/2022] [Indexed: 06/14/2023]
Abstract
The heavy use of pesticides in agricultural areas often leads to the contamination of nearby mosquito larvae breeding sites. Exposure to complex mixtures of agrochemicals can affect the insecticide sensitivity of mosquito larvae. Our study objective was to determine whether agrochemical residues in Anopheline larval breeding sites can affect the tolerance of adults to commonly used adulticides. We focussed on Fludora® Fusion, a vector control insecticide formulation combining two insecticides (deltamethrin and clothianidin) with different modes of action. An. gambiae larvae were exposed to a sub-lethal dose of a mixture of agrochemical pesticides used in a highly active agricultural area on the Ivory Coast. Comparative bioassays with Fludora Fusion mixture and its two insecticide components (deltamethrin and clothianidin) were carried out between adult mosquitoes exposed or not to the agrochemicals at the larval stage. A transcriptomic analysis using RNA sequencing was then performed on larvae and adults to study the molecular mechanisms underlying the phenotypic changes observed. Bioassays revealed a significantly increased tolerance of adult females to clothianidin (2.5-fold) and Fludora Fusion mixture (2.2-fold) following larval exposure to agrochemicals. Significantly increased tolerance to deltamethrin was not observed suggesting that insecticide exposure affects the adult efficacy of the Fludora Fusion mixture mainly through mechanisms acting on clothianidin. Transcriptomic analysis revealed the potential of agrochemicals to induce various resistance mechanisms including cuticle proteins, detoxification action and altered insecticide sequestration. These results suggest that although the Fludora Fusion mixture is effective for adult vector control, its efficacy may be locally affected by the ecological context. The present study also suggests that, although the complex interactions between the use of agrochemicals and vector control insecticides are difficult to decipher in the field, they still must be considered in the context of insecticide resistance management programmes.
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Affiliation(s)
- Marius Gonse Zoh
- Univ. Grenoble-Alpes, Univ. Savoie Mont Blanc, CNRS, LECA, 38000 Grenoble, France.
| | - Jordan Tutagata
- Univ. Grenoble-Alpes, Univ. Savoie Mont Blanc, CNRS, LECA, 38000 Grenoble, France.
| | - Behi K Fodjo
- Centre Suisse de la Recherche Scientifique en Côte d'Ivoire, Côte d'Ivoire
| | | | | | | | | | | | - Jean-Philippe David
- Univ. Grenoble-Alpes, Univ. Savoie Mont Blanc, CNRS, LECA, 38000 Grenoble, France.
| | - Stéphane Reynaud
- Univ. Grenoble-Alpes, Univ. Savoie Mont Blanc, CNRS, LECA, 38000 Grenoble, France.
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17
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Walker KJ, Williams CT, Oladepo FO, Lucas J, Malone D, Paine MJI, Ismail HM. A high-throughput HPLC method for simultaneous quantification of pyrethroid and pyriproxyfen in long-lasting insecticide-treated nets. Sci Rep 2022; 12:9715. [PMID: 35690679 PMCID: PMC9188574 DOI: 10.1038/s41598-022-13768-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2021] [Accepted: 05/27/2022] [Indexed: 11/26/2022] Open
Abstract
Long-lasting insecticide-treated nets (LLINs) play a crucial role in preventing malaria transmission. LLINs should remain effective for at least three years, even after repeated washings. Currently, monitoring insecticides in LLINs is cumbersome, costly, and requires specialized equipment and hazardous solvents. Our aim was to develop a simple, high-throughput and low-resource method for measuring insecticides in LLINs. To extract insecticides, polyethylene-LLIN samples were heated at 85 °C for 45 min in a non-hazardous solvent mix containing dicyclohexylphthalate as an internal standard. The extraction solvent was reduced from 50 to 5 ml using a 0.2 g sample, 90% smaller than the recommended sample size. By optimizing HPLC chromatography, we simultaneously detected pyrethroid and pyriproxyfen insecticides with high sensitivity in LLIN's extract. The method can quantify levels ≥ 0.0015% permethrin, 0.00045% alpha-cypermethrin and 0.00025% pyriproxyfen (w/w) in polyethylene, allowing for insecticide tracking before and after the use of LLINs. This method can be used to assess LLINs with 1% pyriproxyfen (pyriproxyfen-LLIN) or 2% permethrin (Olyset® Net), 1% pyriproxyfen and 2% permethrin (Olyset® Duo), or 0.55% pyriproxyfen and 0.55% alpha-cypermethrin (Royal Gaurd®). One can run 120 samples (40 nets) simultaneously with high precision and accuracy, improving throughput and reducing labour, costs, and environmental impact.
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Affiliation(s)
- Kyle J Walker
- Vector Biology Department, Liverpool School of Tropical Medicine, Pembroke Pl, Liverpool, L3 5QA, UK
| | - Christopher T Williams
- Vector Biology Department, Liverpool School of Tropical Medicine, Pembroke Pl, Liverpool, L3 5QA, UK
| | - Folasade O Oladepo
- Vector Biology Department, Liverpool School of Tropical Medicine, Pembroke Pl, Liverpool, L3 5QA, UK
| | - John Lucas
- Cowleigh Park Farm, Cowleigh Road, Malvern, WR13 5HJ, UK
| | - David Malone
- Innovative Vector Control Consortium, Liverpool School of Tropical Medicine, Pembroke Place, Liverpool, L3 5QA, UK
| | - Mark J I Paine
- Vector Biology Department, Liverpool School of Tropical Medicine, Pembroke Pl, Liverpool, L3 5QA, UK
| | - Hanafy M Ismail
- Vector Biology Department, Liverpool School of Tropical Medicine, Pembroke Pl, Liverpool, L3 5QA, UK.
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Brozak SJ, Mohammed-Awel J, Gumel AB. Mathematics of a single-locus model for assessing the impacts of pyrethroid resistance and temperature on population abundance of malaria mosquitoes. Infect Dis Model 2022; 7:277-316. [PMID: 35782338 PMCID: PMC9234087 DOI: 10.1016/j.idm.2022.05.007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2022] [Revised: 05/25/2022] [Accepted: 05/25/2022] [Indexed: 11/18/2022] Open
Abstract
This study presents a genetic-ecology modeling framework for assessing the combined impacts of insecticide resistance, temperature variability, and insecticide-based interventions on the population abundance and control of malaria mosquitoes by genotype. Rigorous analyses of the model we developed reveal that the boundary equilibrium with only mosquitoes of homozygous sensitive (resistant) genotype is locally-asymptotically stable whenever a certain ecological threshold, denoted by R0SS(R0RR), is less than one. Furthermore, genotype i drives genotype j to extinction whenever R0j>1 and R0i<1 (where i, j = SS or RR, with i ≠ j). The model exhibits the phenomenon of bistability when both thresholds are less than one. In such a bistable situation, convergence to any of the two boundary equilibria depends on the initial allele distribution in the state variables of the model. Furthermore, in this bistable case, where max{R0SS,R0RR}<1, the basin of attraction of the boundary equilibrium of the mosquito genotype with lower value of the ecological threshold is larger. Specifically, the basin of attraction of the boundary equilibrium for genotype i is larger than that of genotype j if R0i<R0j<1. When both ecological thresholds exceed one (min{R0SS,R0RR}>1), the two boundary equilibria lose their stability, and a coexistence equilibrium (where all three mosquito genotypes coexist) becomes locally-asymptotically stable. Global sensitivity analysis shows that the key parameters that greatly influence the dynamics and population abundance of resistant mosquitoes include the proportion of new adult mosquitoes that are females, the insecticide-induced mortality rate of adult female mosquitoes, the coverage level and efficacy of adulticides used in the community, the oviposition rates for eggs of heterozygous and homozygous resistant genotypes, and the modification parameter accounting for the reduction in insecticide-induced mortality due to resistance. Numerical simulations show that the adult mosquito population increases with increasing temperature until a peak is reached at 31 °C, and declines thereafter. Simulating the model for moderate and high adulticide coverage, together with varying fitness costs of resistance, shows a switch in the dominant genotype at equilibrium as temperature is varied. In other words, this study shows that, for certain combinations of adulticide coverage and fitness costs of insecticide resistance, increases in temperature could result in effective management of resistance (by causing the switch from a stable resistant-only boundary equilibrium (at 18 °C) to a stable sensitive-only boundary equilibrium (at 25 °C)). Finally, this study shows that, for moderate fitness costs of resistance, density-dependent larval mortality suppresses the total population of adult mosquitoes with the resistant allele for all temperature values in the range [18 °C–36 °C].
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Affiliation(s)
- Samantha J. Brozak
- School of Mathematical and Statistical Sciences, Arizona State University, Tempe, AZ, 85287, USA
| | - Jemal Mohammed-Awel
- Department of Mathematics, Morgan State University, Baltimore, MD, 21251, USA
| | - Abba B. Gumel
- School of Mathematical and Statistical Sciences, Arizona State University, Tempe, AZ, 85287, USA
- Department of Applied Mathematics, University of Waterloo, Waterloo, Ontario, Canada
- Department of Mathematics and Applied Mathematics, University of Pretoria, Pretoria, 0002, South Africa
- Corresponding author. School of Mathematical and Statistical Sciences, Arizona State University, Tempe, AZ, 85287, USA.
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Dzik S, Mituniewicz T, Beisenov A. Efficacy of a Biocidal Paint in Controlling Alphitobius diaperinus (Panzer) (Coleoptera: Tenebrionidae) and Improving the Quality of Air and Litter in Poultry Houses. Animals (Basel) 2022; 12:1264. [PMID: 35625110 PMCID: PMC9137729 DOI: 10.3390/ani12101264] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2022] [Revised: 05/11/2022] [Accepted: 05/12/2022] [Indexed: 02/01/2023] Open
Abstract
Effective disinfection and disinsection are the keys to successful operation of modern poultry farms and the safety of poultry products. The cleaning and disinfection of poultry houses are important aspects of farm hygiene management. The correct execution of all steps of cleaning, disinfection, and disinsection procedures and the use of appropriate products are crucial for the prevention and control of zoonotic and animal diseases. In this study it was assumed that a water-based slow-release biocidal paint could be useful in controlling insect pests such as Alphitobius diaperinus and reducing microbiological contamination of air and litter in poultry houses and have a beneficial effect on microclimate in poultry houses. Therefore, the locations of A. diaperinus in the poultry houses, the microbiological contamination of air and litter, as well as the microclimatic conditions in the houses and the physicochemical parameters of the litter were evaluated. The results suggest that the tested biocidal paint could be an effective alternative to other insecticides and disinfectants. Additionally, the research is of a practical nature and may be very useful for poultry producers in controlling A. diaperinus populations and maintaining proper hygiene in poultry houses. Further research is needed.
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Affiliation(s)
- Sara Dzik
- Department of Animal and Environmental Hygiene, University of Warmia and Mazury in Olsztyn, 5 Oczapowski Street, 10-719 Olsztyn, Poland;
| | - Tomasz Mituniewicz
- Department of Animal and Environmental Hygiene, University of Warmia and Mazury in Olsztyn, 5 Oczapowski Street, 10-719 Olsztyn, Poland;
| | - Ariphzan Beisenov
- Department of Technology and Biological Resources, Kazakh National Agrarian Research University, 8 Abai Avenue, Almaty 050010, Kazakhstan;
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20
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Machani MG, Ochomo E, Amimo F, Mukabana WR, Githeko AK, Yan G, Afrane YA. Behavioral responses of pyrethroid resistant and susceptible Anopheles gambiae mosquitoes to insecticide treated bed net. PLoS One 2022; 17:e0266420. [PMID: 35390050 PMCID: PMC8989192 DOI: 10.1371/journal.pone.0266420] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2021] [Accepted: 03/19/2022] [Indexed: 11/19/2022] Open
Abstract
Background Long-lasting insecticidal nets are an effective tool in reducing malaria transmission. However, with increasing insecticide resistance little is known about how physiologically resistant malaria vectors behave around a human-occupied bed net, despite their importance in malaria transmission. We used the Mbita bednet trap to assess the host-seeking behavior of insecticide-resistant Anopheles gambiae mosquitoes under semi-field conditions. The trap incorporates a mosquito netting panel which acts as a mechanical barrier that prevents host-seeking mosquitoes from reaching the human host baiting the trap. Methods Susceptible and pyrethroid-resistant colonies of female Anopheles gambiae mosquitoes aged 3–5 days old were used in this study. The laboratory-bred mosquitoes were color-marked with fluorescent powders and released inside a semi-field environment where a human subject slept inside a bednet trap erected in a traditional African hut. The netting panel inside the trap was either untreated (control) or deltamethrin-impregnated. The mosquitoes were released outside the hut. Only female mosquitoes were used. A window exit trap was installed on the hut to catch mosquitoes exiting the hut. A prokopack aspirator was used to collect indoor and outdoor resting mosquitoes. In addition, clay pots were placed outside the hut to collect outdoor resting mosquitoes. The F1 progeny of wild-caught mosquitoes were also used in these experiments. Results The mean number of resistant mosquitoes trapped in the deltamethrin-impregnated bed net trap was higher (mean = 50.21± 3.7) compared to susceptible counterparts (mean + 22.4 ± 1.31) (OR = 1.445; P<0.001). More susceptible mosquitoes were trapped in an untreated (mean = 51.9 ± 3.6) compared to a deltamethrin-treated bed net trap (mean = 22.4 ± 1.3) (OR = 2.65; P<0.001). Resistant mosquitoes were less likely to exit the house when a treated bed net was present compared to the susceptible mosquitoes. The number of susceptible mosquitoes caught resting outdoors (mean + 28.6 ± 2.22) when a treated bed net was hanged was higher than when untreated bednet was present inside the hut (mean = 4.6 ± 0.74). The susceptible females were 2.3 times more likely to stay outdoors away from the treated bed net (OR = 2.25; 95% CI = [1.7–2.9]; P<0.001). Conclusion The results show that deltamethrin-treatment of netting panels inside the bednet trap did not alter the host-seeking behavior of insecticide-resistant female An. gambiae mosquitoes. On the contrary, susceptible females exited the hut and remained outdoors when a treated net was used. However, further investigations of the behavior of resistant mosquitoes under natural conditions should be undertaken to confirm these observations and improve the current intervention which are threatened by insecticide resistance and altered vector behavior.
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Affiliation(s)
- Maxwell G. Machani
- Entomology Section, Centre for Global Health Research, Kenya Medical Research Institute, Kisumu, Kenya
- School of Health Sciences, Jaramogi Oginga Odinga University of Science and Technology, Kisumu, Kenya
- * E-mail: (MGM); (YAA)
| | - Eric Ochomo
- Entomology Section, Centre for Global Health Research, Kenya Medical Research Institute, Kisumu, Kenya
| | - Fred Amimo
- School of Health Sciences, Jaramogi Oginga Odinga University of Science and Technology, Kisumu, Kenya
| | - Wolfgang R. Mukabana
- Department of Biology, Faculty of Science and Technology, University of Nairobi, Nairobi, Kenya
- Science for Health Society, Nairobi, Kenya
| | - Andrew K. Githeko
- Entomology Section, Centre for Global Health Research, Kenya Medical Research Institute, Kisumu, Kenya
| | - Guiyun Yan
- Program in Public Health, College of Health Sciences, University of California, Irvine, CA, United States of America
| | - Yaw A. Afrane
- Department of Medical Microbiology, University of Ghana Medical School, College of Health Sciences, University of Ghana, Accra, Ghana
- * E-mail: (MGM); (YAA)
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Tchouakui M, Mugenzi LMJ, Wondji MJ, Tchoupo M, Njiokou F, Wondji CS. A 6.5kb Intergenic Structural Variation Exacerbates the Fitness Cost of P450-Based Metabolic Resistance in the Major African Malaria Vector Anopheles funestus. Genes (Basel) 2022; 13:genes13040626. [PMID: 35456432 PMCID: PMC9025909 DOI: 10.3390/genes13040626] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2022] [Revised: 03/18/2022] [Accepted: 03/25/2022] [Indexed: 11/16/2022] Open
Abstract
Metabolic-based resistance to insecticides limit the control of medically important pests, and it is extremely detrimental in the ongoing struggle to control disease vectors. Elucidating the fitness cost of metabolic resistance in major malaria vectors is vital for successful resistance management. We established the fitness cost of the 6.5kb structural variant (6.5kb-sv) between the duplicated CYP6P9a/b P450s using the hybrid strain generated from the crossing between two An. funestus laboratory strains. Furthermore, we assessed the cumulative impact of this marker with the duplicated P450 genes. We established that individuals that were homozygote for the resistant structural variant (SV) presented reduced fecundity and slow development relative to those that were homozygote for the susceptible SV. Furthermore, we observed that 6.5kb act additively with CYP6P9a and CYP6P9b to exacerbate the reduced fecundity and the increased development time of resistant mosquitoes since double/triple homozygote susceptible (SS/SS/SS) significantly laid more eggs and developed faster than other genotypes. Moreover, a restoration of susceptibility was noted over 10 generations in the insecticide-free environment with an increased proportion of susceptible individuals. This study highlights the negative impact of multiple P450-based resistance on the key physiological traits of malaria vectors. Such high fitness costs suggest that in the absence of selection pressure, the resistant individuals will be outcompeted in the field. Therefore, this should encourage future strategies based on the rotation of insecticides to reduce selection pressure and to slow the spread of pyrethroid resistance.
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Affiliation(s)
- Magellan Tchouakui
- Centre for Research in Infectious Diseases, Yaoundé P.O. Box 13591, Cameroon; (L.M.J.M.); (M.J.W.); (M.T.)
- Parasitology and Ecology Laboratory, Department of Animal Biology and Physiology, Faculty of Science, University of Yaoundé 1, Yaoundé P.O. Box 812, Cameroon;
- Correspondence: (M.T.); (C.S.W.)
| | - Leon M. J. Mugenzi
- Centre for Research in Infectious Diseases, Yaoundé P.O. Box 13591, Cameroon; (L.M.J.M.); (M.J.W.); (M.T.)
- Department of Biochemistry and Molecular Biology, Faculty of Science University of Buea, Buea P.O. Box 63, Cameroon
| | - Murielle J. Wondji
- Centre for Research in Infectious Diseases, Yaoundé P.O. Box 13591, Cameroon; (L.M.J.M.); (M.J.W.); (M.T.)
- Department of Vector Biology, Liverpool School of Tropical Medicine, Pembroke Place, Liverpool L3 5QA, UK
| | - Micareme Tchoupo
- Centre for Research in Infectious Diseases, Yaoundé P.O. Box 13591, Cameroon; (L.M.J.M.); (M.J.W.); (M.T.)
| | - Flobert Njiokou
- Parasitology and Ecology Laboratory, Department of Animal Biology and Physiology, Faculty of Science, University of Yaoundé 1, Yaoundé P.O. Box 812, Cameroon;
| | - Charles S. Wondji
- Centre for Research in Infectious Diseases, Yaoundé P.O. Box 13591, Cameroon; (L.M.J.M.); (M.J.W.); (M.T.)
- Department of Vector Biology, Liverpool School of Tropical Medicine, Pembroke Place, Liverpool L3 5QA, UK
- Correspondence: (M.T.); (C.S.W.)
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22
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Pryce J, Medley N, Choi L. Indoor residual spraying for preventing malaria in communities using insecticide-treated nets. Cochrane Database Syst Rev 2022; 1:CD012688. [PMID: 35038163 PMCID: PMC8763033 DOI: 10.1002/14651858.cd012688.pub3] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
BACKGROUND Insecticide-treated nets (ITNs) and indoor residual spraying (IRS) are used to prevent malaria transmission. Both interventions use insecticides to kill mosquitoes that bite and rest indoors. Adding IRS to ITNs may improve malaria control simply because two interventions can be better than one. Furthermore, IRS may improve malaria control where ITNs are failing due to insecticide resistance. Pyrethroid insecticides are the predominant class of insecticide used for ITNs, as they are more safe than other insecticide classes when in prolonged contact with human skin. While many mosquito populations have developed some resistance to pyrethroid insecticides, a wider range of insecticides can be used for IRS. This review is an update of the previous Cochrane 2019 edition. OBJECTIVES To summarize the effect on malaria of additionally implementing IRS, using non-pyrethroid-like or pyrethroid-like insecticides, in communities currently using ITNs. SEARCH METHODS We searched the Cochrane Infectious Diseases Group Specialized Register; CENTRAL; MEDLINE; and five other databases for records from 1 January 2000 to 8 November 2021, on the basis that ITN programmes did not begin to be implemented as policy before the year 2000. SELECTION CRITERIA We included cluster-randomized controlled trials (cRCTs), interrupted time series (ITS), or controlled before-after studies (CBAs) comparing IRS plus ITNs with ITNs alone. We included studies with at least 50% ITN ownership (defined as the proportion of households owning one or more ITN) in both study arms. DATA COLLECTION AND ANALYSIS Two review authors independently assessed studies for eligibility, analyzed risk of bias, and extracted data. We used risk ratio (RR) and 95% confidence intervals (CI). We stratified by type of insecticide, 'pyrethroid-like' and 'non-pyrethroid-like'; the latter could improve malaria control better than adding IRS insecticides that have the same way of working as the insecticide on ITNs ('pyrethroid-like'). We used subgroup analysis of ITN usage in the studies to explore heterogeneity. We assessed the certainty of evidence using the GRADE approach. MAIN RESULTS Eight cRCTs (10 comparisons), one CBA, and one ITS study, all conducted since 2008 in sub-Saharan Africa, met our inclusion criteria. The primary vectors in all sites were mosquitoes belonging to the Anopheles gambiae s.l. complex species; five studies in Benin, Mozambique, Ghana, Sudan, and Tanzania also reported the vector Anopheles funestus. Five cRCTs and both quasi-experimental design studies used insecticides with targets different to pyrethroids (two used bendiocarb, three used pirimiphos-methyl, and one used propoxur. Each of these studies were conducted in areas where the vectors were described as resistant or highly resistant to pyrethroids. Two cRCTs used dichloro-diphenyl-trichlorethane (DDT), an insecticide with the same target as pyrethroids. The remaining cRCT used both types of insecticide (pyrethroid deltamethrin in the first year, switching to bendiocarb for the second year). Indoor residual spraying using 'non-pyrethroid-like' insecticides Six studies were included (four cRCTs, one CBA, and one ITS). Our main analysis for prevalence excluded a study at high risk of bias due to repeated sampling of the same population. This risk did not apply to other outcomes. Overall, the addition of IRS reduced malaria parasite prevalence (RR 0.61, 95% CI 0.42 to 0.88; 4 cRCTs, 16,394 participants; high-certainty evidence). IRS may also reduce malaria incidence on average (rate ratio 0.86, 95% CI 0.61 to 1.23; 4 cRCTs, 323,631 child-years; low-certainty evidence) but the effect was absent in two studies. Subgroup analyses did not explain the qualitative heterogeneity between studies. One cRCT reported no effect on malaria incidence or parasite prevalence in the first year, when a pyrethroid-like insecticide was used for IRS, but showed an effect on both outcomes in the second year, when a non-pyrethroid-like IRS was used. The addition of IRS may also reduce anaemia prevalence (RR 0.71, 95% CI 0.38 to 1.31; 3 cRCTs, 4288 participants; low-certainty evidence). Four cRCTs reported the impact of IRS on entomological inoculation rate (EIR), with variable results; overall, we do not know if IRS had any effect on the EIR in communities using ITNs (very low-certainty evidence). Studies also reported the adult mosquito density and the sporozoite rate, but we could not summarize or pool these entomological outcomes due to differences in the reported data. Three studies measured the prevalence of pyrethroid resistance before and after IRS being introduced: there was no difference detected, but these data are limited. Indoor residual spraying using 'pyrethroid-like' insecticides Adding IRS using a pyrethroid-like insecticide did not appear to markedly alter malaria incidence (rate ratio 1.07, 95% CI 0.80 to 1.43; 2 cRCTs, 15,717 child-years; moderate-certainty evidence), parasite prevalence (RR 1.11, 95% CI 0.86 to 1.44; 3 cRCTs, 10,820 participants; moderate-certainty evidence), or anaemia prevalence (RR 1.12, 95% CI 0.89 to 1.40; 1 cRCT, 4186 participants; low-certainty evidence). Data on EIR were limited so no conclusion was made (very low-certainty evidence). AUTHORS' CONCLUSIONS in communities using ITNs, the addition of IRS with 'non-pyrethroid-like' insecticides was associated with reduced malaria prevalence. Malaria incidence may also be reduced on average, but there was unexplained qualitative heterogeneity, and the effect may therefore not be observed in all settings. When using 'pyrethroid-like' insecticides, there was no detectable additional benefit of IRS in communities using ITNs.
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Affiliation(s)
- Joseph Pryce
- Department of Clinical Sciences, Liverpool School of Tropical Medicine, Liverpool, UK
| | - Nancy Medley
- Department of Clinical Sciences, Liverpool School of Tropical Medicine, Liverpool, UK
| | - Leslie Choi
- Department of Vector Biology, Liverpool School of Tropical Medicine, Liverpool, UK
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Ngufor C, Fagbohoun J, Agbevo A, Ismail H, Challenger JD, Churcher TS, Rowland M. Comparative efficacy of two pyrethroid-piperonyl butoxide nets (Olyset Plus and PermaNet 3.0) against pyrethroid resistant malaria vectors: a non-inferiority assessment. Malar J 2022; 21:20. [PMID: 35016676 PMCID: PMC8753866 DOI: 10.1186/s12936-022-04041-9] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2021] [Accepted: 01/03/2022] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Pyrethroid-PBO nets were conditionally recommended for control of malaria transmitted by mosquitoes with oxidase-based pyrethroid-resistance based on epidemiological evidence of additional protective effect with Olyset Plus compared to a pyrethroid-only net (Olyset Net). Entomological studies can be used to assess the comparative performance of other brands of pyrethroid-PBO ITNs to Olyset Plus. METHODS An experimental hut trial was performed in Cové, Benin to compare PermaNet 3.0 (deltamethrin plus PBO on roof panel only) to Olyset Plus (permethrin plus PBO on all panels) against wild pyrethroid-resistant Anopheles gambiae sensu lato (s.l.) following World Health Organization (WHO) guidelines. Both nets were tested unwashed and after 20 standardized washes compared to Olyset Net. Laboratory bioassays were also performed to help explain findings in the experimental huts. RESULTS With unwashed nets, mosquito mortality was higher in huts with PermaNet 3.0 compared to Olyset Plus (41% vs. 28%, P < 0.001). After 20 washes, mortality declined significantly with PermaNet 3.0 (41% unwashed vs. 17% after washing P < 0.001), but not with Olyset Plus (28% unwashed vs. 24% after washing P = 0.433); Olyset Plus induced significantly higher mortality than PermaNet 3.0 and Olyset Net after 20 washes. PermaNet 3.0 showed a higher wash retention of PBO compared to Olyset Plus. A non-inferiority analysis performed with data from unwashed and washed nets together using a margin recommended by the WHO, showed that PermaNet 3.0 was non-inferior to Olyset Plus in terms of mosquito mortality (25% with Olyset Plus vs. 27% with PermaNet 3.0, OR = 1.528, 95%CI = 1.02-2.29) but not in reducing mosquito feeding (25% with Olyset Plus vs. 30% with PermaNet 3.0, OR = 1.192, 95%CI = 0.77-1.84). Both pyrethroid-PBO nets were superior to Olyset Net. CONCLUSION Olyset Plus outperformed PermaNet 3.0 in terms of its ability to cause greater margins of improved mosquito mortality compared to a standard pyrethroid net, after multiple standardized washes. However, using a margin of non-inferiority defined by the WHO, PermaNet 3.0 was non-inferior to Olyset Plus in inducing mosquito mortality. Considering the low levels of mortality observed and increasing pyrethroid-resistance in West Africa, it is unclear whether either of these nets would demonstrate the same epidemiological impact observed in community trials in East Africa.
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Affiliation(s)
- Corine Ngufor
- London School of Hygiene and Tropical Medicine (LSHTM), London, UK. .,Centre de Recherches Entomologiques de Cotonou (CREC), Cotonou, Benin. .,Pan African Malaria Vector Research Consortium (PAMVERC), Cotonou, Benin.
| | - Josias Fagbohoun
- Centre de Recherches Entomologiques de Cotonou (CREC), Cotonou, Benin ,Pan African Malaria Vector Research Consortium (PAMVERC), Cotonou, Benin
| | - Abel Agbevo
- Centre de Recherches Entomologiques de Cotonou (CREC), Cotonou, Benin ,Pan African Malaria Vector Research Consortium (PAMVERC), Cotonou, Benin
| | - Hanafy Ismail
- grid.48004.380000 0004 1936 9764Liverpool School of Tropical Medicine, Liverpool, L3 5QA UK
| | - Joseph D. Challenger
- grid.7445.20000 0001 2113 8111MRC Centre for Global Infectious Disease Analysis, Infectious Disease Epidemiology, Imperial College London, Norfolk Place, London, W2 1PG UK
| | - Thomas S. Churcher
- grid.7445.20000 0001 2113 8111MRC Centre for Global Infectious Disease Analysis, Infectious Disease Epidemiology, Imperial College London, Norfolk Place, London, W2 1PG UK
| | - Mark Rowland
- grid.8991.90000 0004 0425 469XLondon School of Hygiene and Tropical Medicine (LSHTM), London, UK ,Pan African Malaria Vector Research Consortium (PAMVERC), Cotonou, Benin
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24
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Wolie RZ, Koffi AA, Ahoua Alou LP, Sternberg ED, N'Nan-Alla O, Dahounto A, Yapo FHA, Kanh KMH, Camara S, Oumbouke WA, Tia IZ, Nguetta SPA, Thomas MB, NGuessan R. Evaluation of the interaction between insecticide resistance-associated genes and malaria transmission in Anopheles gambiae sensu lato in central Côte d'Ivoire. Parasit Vectors 2021; 14:581. [PMID: 34801086 PMCID: PMC8605510 DOI: 10.1186/s13071-021-05079-5] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2021] [Accepted: 10/22/2021] [Indexed: 11/10/2022] Open
Abstract
Background There is evidence that the knockdown resistance gene (Kdr) L1014F and acetylcholinesterase-1 gene (Ace-1R) G119S mutations involved in pyrethroid and carbamate resistance in Anopheles gambiae influence malaria transmission in sub-Saharan Africa. This is likely due to changes in the behaviour, life history and vector competence and capacity of An. gambiae. In the present study, performed as part of a two-arm cluster randomized controlled trial evaluating the impact of household screening plus a novel insecticide delivery system (In2Care Eave Tubes), we investigated the distribution of insecticide target site mutations and their association with infection status in wild An. gambiae sensu lato (s.l.) populations. Methods Mosquitoes were captured in 40 villages around Bouaké by human landing catch from May 2017 to April 2019. Randomly selected samples of An. gambiae s.l. that were infected or not infected with Plasmodium sp. were identified to species and then genotyped for Kdr L1014F and Ace-1R G119S mutations using quantitative polymerase chain reaction assays. The frequencies of the two alleles were compared between Anopheles coluzzii and Anopheles gambiae and then between infected and uninfected groups for each species. Results The presence of An. gambiae (49%) and An. coluzzii (51%) was confirmed in Bouaké. Individuals of both species infected with Plasmodium parasites were found. Over the study period, the average frequency of the Kdr L1014F and Ace-1R G119S mutations did not vary significantly between study arms. However, the frequencies of the Kdr L1014F and Ace-1R G119S resistance alleles were significantly higher in An. gambiae than in An. coluzzii [odds ratio (95% confidence interval): 59.64 (30.81–131.63) for Kdr, and 2.79 (2.17–3.60) for Ace-1R]. For both species, there were no significant differences in Kdr L1014F or Ace-1R G119S genotypic and allelic frequency distributions between infected and uninfected specimens (P > 0.05). Conclusions Either alone or in combination, Kdr L1014F and Ace-1R G119S showed no significant association with Plasmodium infection in wild An. gambiae and An. coluzzii, demonstrating the similar competence of these species for Plasmodium transmission in Bouaké. Additional factors including behavioural and environmental ones that influence vector competence in natural populations, and those other than allele measurements (metabolic resistance factors) that contribute to resistance, should be considered when establishing the existence of a link between insecticide resistance and vector competence. Graphical Abstract ![]()
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Affiliation(s)
- Rosine Z Wolie
- Unité de Recherche et de Pédagogie de Génétique, Université Félix Houphouët-Boigny, UFR Biosciences, Abidjan, Côte d'Ivoire. .,Vector Control Product Evaluation Centre, Institut Pierre Richet (VCPEC-IPR), Bouaké, Côte d'Ivoire. .,Institut Pierre Richet (IPR), Institut National de Santé Publique (INSP), Bouaké, Côte d'Ivoire.
| | - Alphonsine A Koffi
- Vector Control Product Evaluation Centre, Institut Pierre Richet (VCPEC-IPR), Bouaké, Côte d'Ivoire.,Institut Pierre Richet (IPR), Institut National de Santé Publique (INSP), Bouaké, Côte d'Ivoire
| | - Ludovic P Ahoua Alou
- Vector Control Product Evaluation Centre, Institut Pierre Richet (VCPEC-IPR), Bouaké, Côte d'Ivoire.,Institut Pierre Richet (IPR), Institut National de Santé Publique (INSP), Bouaké, Côte d'Ivoire
| | - Eleanore D Sternberg
- Department of Entomology, Center for Infectious Disease Dynamics, The Pennsylvania State University, University Park, PA, USA.,Department of Vector Biology, Liverpool School of Tropical Medicine, Liverpool, L3 5QA, UK
| | - Oulo N'Nan-Alla
- Unité de Recherche et de Pédagogie de Génétique, Université Félix Houphouët-Boigny, UFR Biosciences, Abidjan, Côte d'Ivoire
| | - Amal Dahounto
- Vector Control Product Evaluation Centre, Institut Pierre Richet (VCPEC-IPR), Bouaké, Côte d'Ivoire
| | - Florent H A Yapo
- Vector Control Product Evaluation Centre, Institut Pierre Richet (VCPEC-IPR), Bouaké, Côte d'Ivoire
| | - Kpahe M H Kanh
- Unité de Recherche et de Pédagogie de Génétique, Université Félix Houphouët-Boigny, UFR Biosciences, Abidjan, Côte d'Ivoire
| | - Soromane Camara
- Vector Control Product Evaluation Centre, Institut Pierre Richet (VCPEC-IPR), Bouaké, Côte d'Ivoire.,Institut Pierre Richet (IPR), Institut National de Santé Publique (INSP), Bouaké, Côte d'Ivoire
| | - Welbeck A Oumbouke
- Vector Control Product Evaluation Centre, Institut Pierre Richet (VCPEC-IPR), Bouaké, Côte d'Ivoire.,Innovative Vector Control Consortium, IVCC, Liverpool, UK
| | - Innocent Z Tia
- Vector Control Product Evaluation Centre, Institut Pierre Richet (VCPEC-IPR), Bouaké, Côte d'Ivoire.,Institut Pierre Richet (IPR), Institut National de Santé Publique (INSP), Bouaké, Côte d'Ivoire.,Université Alassane Ouattara, Bouaké, Côte d'Ivoire
| | - Simon-Pierre A Nguetta
- Unité de Recherche et de Pédagogie de Génétique, Université Félix Houphouët-Boigny, UFR Biosciences, Abidjan, Côte d'Ivoire
| | - Matthew B Thomas
- Department of Entomology, Center for Infectious Disease Dynamics, The Pennsylvania State University, University Park, PA, USA
| | - Raphael NGuessan
- Vector Control Product Evaluation Centre, Institut Pierre Richet (VCPEC-IPR), Bouaké, Côte d'Ivoire.,Institut Pierre Richet (IPR), Institut National de Santé Publique (INSP), Bouaké, Côte d'Ivoire.,Department of Disease Control, London School of Hygiene and Tropical Medicine, London, UK
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Zoh MG, Bonneville JM, Tutagata J, Laporte F, Fodjo BK, Mouhamadou CS, Sadia CG, McBeath J, Schmitt F, Horstmann S, Reynaud S, David JP. Experimental evolution supports the potential of neonicotinoid-pyrethroid combination for managing insecticide resistance in malaria vectors. Sci Rep 2021; 11:19501. [PMID: 34593941 PMCID: PMC8484614 DOI: 10.1038/s41598-021-99061-x] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2021] [Accepted: 09/20/2021] [Indexed: 11/22/2022] Open
Abstract
The introduction of neonicotinoids for managing insecticide resistance in mosquitoes is of high interest as they interact with a biochemical target not previously used in public health. In this concern, Bayer developed a combination of the neonicotinoid clothianidin and the pyrethroid deltamethrin (brand name Fludora Fusion) as a new vector control tool. Although this combination proved to be efficient against pyrethroid-resistant mosquitoes, its ability to prevent the selection of pyrethroid and neonicotinoid resistance alleles was not investigated. In this context, the objective of this work was to study the dynamics and the molecular mechanisms of resistance of An. gambiae to the separated or combined components of this combination. A field-derived An. gambiae line carrying resistance alleles to multiple insecticides at low frequencies was used as a starting for 33 successive generations of controlled selection. Resistance levels to each insecticide and target site mutation frequencies were monitored throughout the selection process. Cross resistance to other public health insecticides were also investigated. RNA-seq was used to compare gene transcription variations and polymorphisms across all lines. This study confirmed the potential of this insecticide combination to impair the selection of resistance as compared to its two separated components. Deltamethrin selection led to the rapid enrichment of the kdr L1014F target-site mutation. Clothianidin selection led to the over-transcription of multiple cytochrome P450s including some showing high homology with those conferring neonicotinoid resistance in other insects. A strong selection signature associated with clothianidin selection was also observed on a P450 gene cluster previously associated with resistance. Within this cluster, the gene CYP6M1 showed the highest selection signature together with a transcription profile supporting a role in clothianidin resistance. Modelling the impact of point mutations selected by clothianidin on CYP6M1 protein structure showed that selection retained a protein variant with a modified active site potentially enhancing clothianidin metabolism. In the context of the recent deployment of neonicotinoids for mosquito control and their frequent usage in agriculture, the present study highlights the benefit of combining them with other insecticides for preventing the selection of resistance and sustaining vector control activities.
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Affiliation(s)
- Marius Gonse Zoh
- Laboratoire d'Ecologie Alpine (LECA) UMR 5553 CNRS Grenoble-Alpes University, Grenoble, France
| | - Jean-Marc Bonneville
- Laboratoire d'Ecologie Alpine (LECA) UMR 5553 CNRS Grenoble-Alpes University, Grenoble, France
| | - Jordan Tutagata
- Laboratoire d'Ecologie Alpine (LECA) UMR 5553 CNRS Grenoble-Alpes University, Grenoble, France
| | - Frederic Laporte
- Laboratoire d'Ecologie Alpine (LECA) UMR 5553 CNRS Grenoble-Alpes University, Grenoble, France
| | - Behi K Fodjo
- Centre Suisse de La Recherche Scientifique (CSRS), Abidjan, Côte d'Ivoire
| | | | - Christabelle Gba Sadia
- Centre Suisse de La Recherche Scientifique (CSRS), Abidjan, Côte d'Ivoire.,University of Nangui Abrogoua, Abidjan, Côte d'Ivoire
| | - Justin McBeath
- Bayer CropScience Ltd, Cambridge Science Park, Cambridge, UK
| | | | | | - Stephane Reynaud
- Laboratoire d'Ecologie Alpine (LECA) UMR 5553 CNRS Grenoble-Alpes University, Grenoble, France
| | - Jean-Philippe David
- Laboratoire d'Ecologie Alpine (LECA) UMR 5553 CNRS Grenoble-Alpes University, Grenoble, France.
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26
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Transfluthrin eave-positioned targeted insecticide (EPTI) reduces human landing rate (HLR) of pyrethroid resistant and susceptible malaria vectors in a semi-field simulated peridomestic space. Malar J 2021; 20:357. [PMID: 34461911 PMCID: PMC8404287 DOI: 10.1186/s12936-021-03880-2] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2021] [Accepted: 08/15/2021] [Indexed: 02/07/2023] Open
Abstract
Background Volatile pyrethroids (VPs) are proven to reduce human–vector contact for mosquito vectors. With increasing resistance to pyrethroids in mosquitoes, the efficacy of VPs, such as transfluthrin, may be compromised. Therefore, experiments were conducted to determine if the efficacy of transfluthrin eave-positioned targeted insecticide (EPTI) depends on the resistance status of malaria vectors. Methods Ribbons treated with 5.25 g transfluthrin or untreated controls were used around the eaves of an experimental hut as EPTI inside a semi-field system. Mosquito strains with different levels of pyrethroid resistance were released simultaneously, recaptured by means of human landing catches (HLCs) and monitored for 24-h mortality. Technical-grade (TG) transfluthrin was used, followed by emulsifiable concentrate (EC) transfluthrin and additional mosquito strains. Generalized linear mixed models with binomial distribution were used to determine the impact of transfluthrin and mosquito strain on mosquito landing rates and 24-h mortality. Results EPTI treated with 5.25 g of either TG or EC transfluthrin significantly reduced HLR of all susceptible and resistant Anopheles mosquitoes (Odds Ratio (OR) ranging from 0.14 (95% Confidence Interval (CI) [0.11–0.17], P < 0.001) to 0.57, (CI [0.42–0.78] P < 0.001). Both TG and EC EPTI had less impact on landing for the resistant Anopheles arabiensis (Mbita strain) compared to the susceptible Anopheles gambiae (Ifakara strain) (OR 1.50 [95% CI 1.18–1.91] P < 0.001) and (OR 1.67 [95% CI 1.29–2.17] P < 0.001), respectively. The EC EPTI also had less impact on the resistant An. arabiensis (Kingani strain) (OR 2.29 [95% CI 1.78–2.94] P < 0.001) compared to the control however the TG EPTI was equally effective against the resistant Kingani strain and susceptible Ifakara strain (OR 1.03 [95% CI 0.82–1.32] P = 0.75). Finally the EC EPTI was equally effective against the susceptible An. gambiae (Kisumu strain) and the resistant An. gambiae (Kisumu-kdr strain) (OR 0.98 [95% CI 0.74–1.30] P = 0.90). Conclusions Transfluthrin-treated EPTI could be useful in areas with pyrethroid-resistant mosquitoes, but it remains unclear whether stronger resistance to pyrethroids will undermine the efficacy of transfluthrin. At this dosage, transfluthrin EPTI cannot be used to kill exposed mosquitoes. Supplementary Information The online version contains supplementary material available at 10.1186/s12936-021-03880-2.
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Oxborough RM, Seyoum A, Yihdego Y, Chabi J, Wat'senga F, Agossa FR, Coleman S, Musa SL, Faye O, Okia M, Bayoh M, Alyko E, Rakotoson JD, Masendu H, Sovi A, Gadiaga L, Abong'o B, Opondo K, Baber I, Dabire R, Gnanguenon V, Yohannes G, Varela K, Fondjo E, Carlson J, Armistead JS, Dengela D. Determination of the discriminating concentration of chlorfenapyr (pyrrole) and Anopheles gambiae sensu lato susceptibility testing in preparation for distribution of Interceptor® G2 insecticide-treated nets. Malar J 2021; 20:316. [PMID: 34261475 PMCID: PMC8278723 DOI: 10.1186/s12936-021-03847-3] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2021] [Accepted: 07/06/2021] [Indexed: 11/16/2022] Open
Abstract
Background Following agricultural use and large-scale distribution of insecticide-treated nets (ITNs), malaria vector resistance to pyrethroids is widespread in sub-Saharan Africa. Interceptor® G2 is a new dual active ingredient (AI) ITN treated with alpha-cypermethrin and chlorfenapyr for the control of pyrethroid-resistant malaria vectors. In anticipation of these new nets being more widely distributed, testing was conducted to develop a chlorfenapyr susceptibility bioassay protocol and gather susceptibility information. Methods Bottle bioassay tests were conducted using five concentrations of chlorfenapyr at 12.5, 25, 50, 100, and 200 µg AI/bottle in 10 countries in sub-Saharan Africa using 13,639 wild-collected Anopheles gambiae sensu lato (s.l.) (56 vector populations per dose) and 4,494 pyrethroid-susceptible insectary mosquitoes from 8 colonized strains. In parallel, susceptibility tests were conducted using a provisional discriminating concentration of 100 µg AI/bottle in 16 countries using 23,422 wild-collected, pyrethroid-resistant An. gambiae s.l. (259 vector populations). Exposure time was 60 min, with mortality recorded at 24, 48 and 72 h after exposure. Results Median mortality rates (up to 72 h after exposure) of insectary colony mosquitoes was 100% at all five concentrations tested, but the lowest dose to kill all mosquitoes tested was 50 µg AI/bottle. The median 72-h mortality of wild An. gambiae s.l. in 10 countries was 71.5, 90.5, 96.5, 100, and 100% at concentrations of 12.5, 25, 50, 100, and 200 µg AI/bottle, respectively. Log-probit analysis of the five concentrations tested determined that the LC95 of wild An. gambiae s.l. was 67.9 µg AI/bottle (95% CI: 48.8–119.5). The discriminating concentration of 203.8 µg AI/bottle (95% CI: 146–359) was calculated by multiplying the LC95 by three. However, the difference in mortality between 100 and 200 µg AI/bottle was minimal and large-scale testing using 100 µg AI/bottle with wild An. gambiae s.l. in 16 countries showed that this concentration was generally suitable, with a median mortality rate of 100% at 72 h. Conclusions This study determined that 100 or 200 µg AI/bottle chlorfenapyr in bottle bioassays are suitable discriminating concentrations for monitoring susceptibility of wild An. gambiae s.l., using mortality recorded up to 72 h. Testing in 16 countries in sub-Saharan Africa demonstrated vector susceptibility to chlorfenapyr, including mosquitoes with multiple resistance mechanisms to pyrethroids. Supplementary Information The online version contains supplementary material available at 10.1186/s12936-021-03847-3.
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Affiliation(s)
- Richard M Oxborough
- PMI VectorLink Project, Abt Associates, 6130 Executive Blvd, Rockville, MD, 20852, USA.
| | - Aklilu Seyoum
- PMI VectorLink Project, Abt Associates, 6130 Executive Blvd, Rockville, MD, 20852, USA
| | - Yemane Yihdego
- PMI VectorLink Project, Abt Associates, 6130 Executive Blvd, Rockville, MD, 20852, USA
| | - Joseph Chabi
- PMI VectorLink Project, Abt Associates, 6130 Executive Blvd, Rockville, MD, 20852, USA
| | - Francis Wat'senga
- Entomology Department, National Institute of Biomedical Research, Avenue de la Démocratie, Kinshasa, Democratic Republic of the Congo
| | - Fiacre R Agossa
- PMI VectorLink Project, Abt Associates, Kinshasa, Democratic Republic of the Congo
| | - Sylvester Coleman
- PMI VectorLink Project, Abt Associates, Plot 11 Waterson Road, Fuo, Tamale, Ghana
| | - Samdi Lazarus Musa
- PMI VectorLink Project, Abt Associates, Gte No. 12 TOS Benson Crescent, Utako, Abuja, Nigeria
| | - Ousmane Faye
- Département de Biologie Animale, Université Cheikh Anta Diop, Bp 5005 Dakar-Fann, Dakar, Senegal
| | - Michael Okia
- PMI VectorLink Project, Abt Associates, Tororo, Uganda
| | - Mohamed Bayoh
- PMI VectorLink Project, Abt Associates, Njoka Road, Off Kwacha Road, Olympia, Box 39090, Lusaka, Zambia
| | - Evelyne Alyko
- PMI VectorLink Project, Abt Associates, Njoka Road, Off Kwacha Road, Olympia, Box 39090, Lusaka, Zambia.,PMI VectorLink Project, Abt Associates, Freetown, Sierra Leone
| | - Jean-Desire Rakotoson
- PMI VectorLink Project, Abt Associates, Lot Ex La Sice, Ambalanaomby, Farafangana, Madagascar
| | - Hieronymo Masendu
- PMI VectorLink Project, Abt Associates, 1 Pascoe Avenue, Belgravia, Harare, Zimbabwe
| | - Arthur Sovi
- PMI VectorLink Project, Abt Associates, Cite du Niger 1, Rue 30, Porte 612, Bamako, Mali.,Faculty of Infectious and Tropical Diseases, Disease Control Department, London School of Hygiene and Tropical Medicine, London, WC1E 7HT, UK.,Faculty of Agronomy, University of Parakou, BP 123, Parakou, Benin
| | - Libasse Gadiaga
- PMI VectorLink Project, Abt Associates, Cite du Niger 1, Rue 30, Porte 612, Bamako, Mali
| | - Bernard Abong'o
- PMI VectorLink Project, Abt Associates, Whitehouse, Milimani, Kisumu, Ojijo Oteko Road, P.O. Box 895-40123, Kisumu, Milimani, Kenya
| | - Kevin Opondo
- PMI VectorLink Project, Abt Associates, Whitehouse, Milimani, Kisumu, Ojijo Oteko Road, P.O. Box 895-40123, Kisumu, Milimani, Kenya
| | - Ibrahima Baber
- PMI VectorLink Project, Abt Associates, 16th Street, Beach Side, Sinkor, Monrovia, Liberia
| | - Roch Dabire
- Institute of Health Science Research, Malaria and Tropical Neglected Research Unit, 01 BP 545, Bobo-Dioulasso, Burkina Faso
| | - Virgile Gnanguenon
- PMI VectorLink Project, Abt Associates, Plot 28 Avenue Pierre Ngendandumwe, Bujumbura, Burundi
| | - Gedeon Yohannes
- PMI VectorLink Project, Abt Associates, Gerje Rood Sami Building, Floor 1, Office no 105, P.O. Box : 13646, Addis Ababa, Ethiopia
| | - Kenyssony Varela
- PMI VectorLink Project, Abt Associates, Rua Justino Chemane, No. 237 Sommerschield 2, Maputo, Mozambique
| | - Etienne Fondjo
- PMI VectorLink Project, Abt Associates, P.O. Box 14 025, Mballa II, Dragages, P.O. Box 14 025, Yaounde, Cameroon
| | - Jenny Carlson
- U.S. President's Malaria Initiative, U.S. Agency for International Development, Washington, DC, USA
| | - Jennifer S Armistead
- U.S. President's Malaria Initiative, U.S. Agency for International Development, Washington, DC, USA
| | - Dereje Dengela
- PMI VectorLink Project, Abt Associates, 6130 Executive Blvd, Rockville, MD, 20852, USA
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Clegban CMY, Camara S, Koffi AA, Ahoua Alou LP, Kabran Kouame JP, Koffi AF, Kouassi PK, Moiroux N, Pennetier C. Evaluation of Yahe ® and Panda ® 2.0 long-lasting insecticidal nets against wild pyrethroid-resistant Anopheles gambiae s.l. from Côte d'Ivoire: an experimental hut trial. Parasit Vectors 2021; 14:347. [PMID: 34210362 PMCID: PMC8247218 DOI: 10.1186/s13071-021-04843-x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2021] [Accepted: 06/11/2021] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Long-lasting insecticidal nets (LLINs) have played an important role in reducing the global malaria burden since 2000. They are a core prevention tool used widely by people at risk of malaria. The Vector Control Prequalification mechanism of the Word Health Organization (WHO-Vector Control PQ) established the testing and evaluation guidelines for LLINs before registration for public use. In the present study, two new brands of deltamethrin-impregnated nets (Yahe® LN and Panda® Net 2.0) were evaluated in an experimental hut against wild pyrethroid-resistant Anopheles gambiae s.l. in M'Bé nearby Bouaké, central Côte d'Ivoire. METHODS The performance of Yahe® LN and Panda® Net 2.0 was compared with that of PermaNet 2.0, conventionally treated nets (CTN), and untreated net to assess the blood-feeding inhibition, deterrence, induced exophily, and mortality. RESULTS Cone bioassay results showed that Panda® Net 2.0, PermaNet 2.0 and Yahe® LN (both unwashed and washed 20 times) induced > 95% knockdown or > 80% mortality of the susceptible Anopheles gambiae Kisumu strain. With the pyrethroid-resistant M'Bé strain, mortality rate for all treated nets did not exceed 70%. There was a significant reduction in entry and blood feeding (p < 0.05) and an increase in exophily and mortality rates (p < 0.05) with all treatments compared to untreated nets, except the CTNs. However, the personal protection induced by these treated nets decreased significantly after 20 washes. The performance of Panda® Net 2.0 was equal to PermaNet® 2.0 in terms of inhibiting blood feeding, but better than PermaNet® 2.0 in terms of mortality. CONCLUSION This study showed that Yahe® LN and Panda® Net 2.0 met the WHO Pesticide Evaluation Scheme (WHOPES) criteria to undergo phase III trial at the community level. Due to an increasing spread and development of pyrethroid resistance in malaria vectors, control of malaria transmission must evolve into an integrated vector management relying on a large variety of efficient control tools.
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Affiliation(s)
- Cyntia-Muriel Y Clegban
- Institut Pierre Richet/Institut National de Santé Publique (INSP), Bouaké, Côte d'Ivoire. .,Université Félix Houphouët-Boigny, Abidjan, Côte d'Ivoire. .,MIVEGEC, Univ Montpellier, CNRS, IRD, Montpellier, France.
| | - Soromane Camara
- Institut Pierre Richet/Institut National de Santé Publique (INSP), Bouaké, Côte d'Ivoire.,Université Félix Houphouët-Boigny, Abidjan, Côte d'Ivoire.,MIVEGEC, Univ Montpellier, CNRS, IRD, Montpellier, France
| | - A Alphonsine Koffi
- Institut Pierre Richet/Institut National de Santé Publique (INSP), Bouaké, Côte d'Ivoire
| | - Ludovic P Ahoua Alou
- Institut Pierre Richet/Institut National de Santé Publique (INSP), Bouaké, Côte d'Ivoire
| | | | - A Fernand Koffi
- Institut Pierre Richet/Institut National de Santé Publique (INSP), Bouaké, Côte d'Ivoire
| | | | | | - Cédric Pennetier
- Institut Pierre Richet/Institut National de Santé Publique (INSP), Bouaké, Côte d'Ivoire.,MIVEGEC, Univ Montpellier, CNRS, IRD, Montpellier, France
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Impacts of changes in temperature and exposure time on the median lethal concentrations (LC50) of a combination of organophosphate and pyrethroid in the control of Culex quinquefasciatus, say (Diptera: Culicidae). SCIENTIFIC AFRICAN 2021. [DOI: 10.1016/j.sciaf.2021.e00743] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
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Gleave K, Lissenden N, Chaplin M, Choi L, Ranson H. Piperonyl butoxide (PBO) combined with pyrethroids in insecticide-treated nets to prevent malaria in Africa. Cochrane Database Syst Rev 2021; 5:CD012776. [PMID: 34027998 PMCID: PMC8142305 DOI: 10.1002/14651858.cd012776.pub3] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
BACKGROUND Pyrethroid long-lasting insecticidal nets (LLINs) have been important in the large reductions in malaria cases in Africa, but insecticide resistance in Anopheles mosquitoes threatens their impact. Insecticide synergists may help control insecticide-resistant populations. Piperonyl butoxide (PBO) is such a synergist; it has been incorporated into pyrethroid-LLINs to form pyrethroid-PBO nets, which are currently produced by five LLIN manufacturers and, following a recommendation from the World Health Organization (WHO) in 2017, are being included in distribution campaigns. This review examines epidemiological and entomological evidence on the addition of PBO to pyrethroid nets on their efficacy. OBJECTIVES To compare effects of pyrethroid-PBO nets currently in commercial development or on the market with effects of their non-PBO equivalent in relation to: 1. malaria parasite infection (prevalence or incidence); and 2. entomological outcomes. SEARCH METHODS We searched the Cochrane Infectious Diseases Group (CIDG) Specialized Register, CENTRAL, MEDLINE, Embase, Web of Science, CAB Abstracts, and two clinical trial registers (ClinicalTrials.gov and WHO International Clinical Trials Registry Platform) up to 25 September 2020. We contacted organizations for unpublished data. We checked the reference lists of trials identified by these methods. SELECTION CRITERIA We included experimental hut trials, village trials, and randomized controlled trials (RCTs) with mosquitoes from the Anopheles gambiae complex or the Anopheles funestus group. DATA COLLECTION AND ANALYSIS Two review authors assessed each trial for eligibility, extracted data, and determined the risk of bias for included trials. We resolved disagreements through discussion with a third review author. We analysed data using Review Manager 5 and assessed the certainty of evidence using the GRADE approach. MAIN RESULTS Sixteen trials met the inclusion criteria: 10 experimental hut trials, four village trials, and two cluster-RCTs (cRCTs). Three trials are awaiting classification, and four trials are ongoing. Two cRCTs examined the effects of pyrethroid-PBO nets on parasite prevalence in people living in areas with highly pyrethroid-resistant mosquitoes (< 30% mosquito mortality in discriminating dose assays). At 21 to 25 months post intervention, parasite prevalence was lower in the intervention arm (odds ratio (OR) 0.79, 95% confidence interval (CI) 0.67 to 0.95; 2 trials, 2 comparisons; moderate-certainty evidence). In highly pyrethroid-resistant areas, unwashed pyrethroid-PBO nets led to higher mosquito mortality compared to unwashed standard-LLINs (risk ratio (RR) 1.84, 95% CI 1.60 to 2.11; 14,620 mosquitoes, 5 trials, 9 comparisons; high-certainty evidence) and lower blood feeding success (RR 0.60, 95% CI 0.50 to 0.71; 14,000 mosquitoes, 4 trials, 8 comparisons; high-certainty evidence). However, in comparisons of washed pyrethroid-PBO nets to washed LLINs, we do not know if PBO nets had a greater effect on mosquito mortality (RR 1.20, 95% CI 0.88 to 1.63; 10,268 mosquitoes, 4 trials, 5 comparisons; very low-certainty evidence), although the washed pyrethroid-PBO nets did decrease blood-feeding success compared to standard-LLINs (RR 0.81, 95% CI 0.72 to 0.92; 9674 mosquitoes, 3 trials, 4 comparisons; high-certainty evidence). In areas where pyrethroid resistance is moderate (31% to 60% mosquito mortality), mosquito mortality was higher with unwashed pyrethroid-PBO nets compared to unwashed standard-LLINs (RR 1.68, 95% CI 1.33 to 2.11; 751 mosquitoes, 2 trials, 3 comparisons; moderate-certainty evidence), but there was little to no difference in effects on blood-feeding success (RR 0.90, 95% CI 0.72 to 1.11; 652 mosquitoes, 2 trials, 3 comparisons; moderate-certainty evidence). For washed pyrethroid-PBO nets compared to washed standard-LLINs, we found little to no evidence for higher mosquito mortality or reduced blood feeding (mortality: RR 1.07, 95% CI 0.74 to 1.54; 329 mosquitoes, 1 trial, 1 comparison, low-certainty evidence; blood feeding success: RR 0.91, 95% CI 0.74 to 1.13; 329 mosquitoes, 1 trial, 1 comparison; low-certainty evidence). In areas where pyrethroid resistance is low (61% to 90% mosquito mortality), studies reported little to no difference in the effects of unwashed pyrethroid-PBO nets compared to unwashed standard-LLINs on mosquito mortality (RR 1.25, 95% CI 0.99 to 1.57; 948 mosquitoes, 2 trials, 3 comparisons; moderate-certainty evidence), and we do not know if there was any effect on blood-feeding success (RR 0.75, 95% CI 0.27 to 2.11; 948 mosquitoes, 2 trials, 3 comparisons; very low-certainty evidence). For washed pyrethroid-PBO nets compared to washed standard-LLINs, we do not know if there was any difference in mosquito mortality (RR 1.39, 95% CI 0.95 to 2.04; 1022 mosquitoes, 2 trials, 3 comparisons; very low-certainty evidence) or on blood feeding (RR 1.07, 95% CI 0.49 to 2.33; 1022 mosquitoes, 2 trials, 3 comparisons; low-certainty evidence). In areas where mosquito populations are susceptible to insecticides (> 90% mosquito mortality), there may be little to no difference in the effects of unwashed pyrethroid-PBO nets compared to unwashed standard-LLINs on mosquito mortality (RR 1.20, 95% CI 0.64 to 2.26; 2791 mosquitoes, 2 trials, 2 comparisons; low-certainty evidence). This is similar for washed nets (RR 1.07, 95% CI 0.92 to 1.25; 2644 mosquitoes, 2 trials, 2 comparisons; low-certainty evidence). We do not know if unwashed pyrethroid-PBO nets had any effect on the blood-feeding success of susceptible mosquitoes (RR 0.52, 95% CI 0.12 to 2.22; 2791 mosquitoes, 2 trials, 2 comparisons; very low-certainty evidence). The same applies to washed nets (RR 1.25, 95% CI 0.82 to 1.91; 2644 mosquitoes, 2 trials, 2 comparisons; low-certainty evidence). In village trials comparing pyrethroid-PBO nets to LLINs, there was no difference in sporozoite rate (4 trials, 5 comparisons) nor in mosquito parity (3 trials, 4 comparisons). AUTHORS' CONCLUSIONS In areas of high insecticide resistance, pyrethroid-PBO nets have greater entomological and epidemiological efficacy compared to standard LLINs, with sustained reduction in parasite prevalence, higher mosquito mortality and reduction in mosquito blood feeding rates 21 to 25 months post intervention. Questions remain about the durability of PBO on nets, as the impact of pyrethroid-PBO nets on mosquito mortality was not sustained over 20 washes in experimental hut trials, and epidemiological data on pyrethroid-PBO nets for the full intended three-year life span of the nets is not available. Little evidence is available to support greater entomological efficacy of pyrethroid-PBO nets in areas where mosquitoes show lower levels of resistance to pyrethroids.
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Affiliation(s)
- Katherine Gleave
- Department of Vector Biology, Liverpool School of Tropical Medicine, Liverpool, UK
| | - Natalie Lissenden
- Department of Vector Biology, Liverpool School of Tropical Medicine, Liverpool, UK
| | - Marty Chaplin
- Department of Clinical Sciences, Liverpool School of Tropical Medicine, Liverpool, UK
| | - Leslie Choi
- Department of Vector Biology, Liverpool School of Tropical Medicine, Liverpool, UK
| | - Hilary Ranson
- Department of Vector Biology, Liverpool School of Tropical Medicine, Liverpool, UK
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López Del Amo V, Leger BS, Cox KJ, Gill S, Bishop AL, Scanlon GD, Walker JA, Gantz VM, Choudhary A. Small-Molecule Control of Super-Mendelian Inheritance in Gene Drives. Cell Rep 2021; 31:107841. [PMID: 32610142 PMCID: PMC7587219 DOI: 10.1016/j.celrep.2020.107841] [Citation(s) in RCA: 29] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2019] [Revised: 02/20/2020] [Accepted: 06/09/2020] [Indexed: 11/29/2022] Open
Abstract
Synthetic CRISPR-based gene-drive systems have tremendous potential in public health and agriculture, such as for fighting vector-borne diseases or suppressing crop pest populations. These elements can rapidly spread in a population by breaching the inheritance limit of 50% dictated by Mendel's law of gene segregation, making them a promising tool for population engineering. However, current technologies lack control over their propagation capacity, and there are important concerns about potential unchecked spreading. Here, we describe a gene-drive system in Drosophila that generates an analog inheritance output that can be tightly and conditionally controlled to between 50% and 100%. This technology uses a modified SpCas9 that responds to a synthetic, orally available small molecule, fine-tuning the inheritance probability. This system opens a new avenue to feasibility studies for spatial and temporal control of gene drives using small molecules.
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Affiliation(s)
- Víctor López Del Amo
- Section of Cell and Developmental Biology, University of California San Diego, La Jolla, CA 92093, USA
| | - Brittany S Leger
- Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA 02114, USA
| | - Kurt J Cox
- Chemical Biology and Therapeutics Science, Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA; Department of Medicine, Harvard Medical School, Boston, MA 02115, USA; Divisions of Renal Medicine and Engineering, Brigham and Women's Hospital, Boston, MA 02115, USA
| | - Shubhroz Gill
- Chemical Biology and Therapeutics Science, Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA
| | - Alena L Bishop
- Section of Cell and Developmental Biology, University of California San Diego, La Jolla, CA 92093, USA
| | - Garrett D Scanlon
- Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA 02114, USA
| | - James A Walker
- Center for Genomic Medicine, Massachusetts General Hospital, Boston, MA 02114, USA; Department of Neurology, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA; Cancer Program, Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA.
| | - Valentino M Gantz
- Section of Cell and Developmental Biology, University of California San Diego, La Jolla, CA 92093, USA.
| | - Amit Choudhary
- Chemical Biology and Therapeutics Science, Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA; Department of Medicine, Harvard Medical School, Boston, MA 02115, USA; Divisions of Renal Medicine and Engineering, Brigham and Women's Hospital, Boston, MA 02115, USA.
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Keïta M, Sogoba N, Kané F, Traoré B, Zeukeng F, Coulibaly B, Sodio AB, Traoré SF, Djouaka R, Doumbia S. Multiple Resistance Mechanisms to Pyrethroids Insecticides in Anopheles gambiae sensu lato Population From Mali, West Africa. J Infect Dis 2021; 223:S81-S90. [PMID: 33906223 PMCID: PMC8079131 DOI: 10.1093/infdis/jiaa190] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Background Insecticide-based vector control is responsible for reducing malaria mortality and morbidity. Its success depends on a better knowledge of the vector, its distribution, and resistance status to the insecticides used. In this paper, we assessed Anopheles gambiae sensu lato (A gambiae s.l.) population resistance to pyrethroids in different ecological settings. Methods The World Health Organization standard bioassay test was used to assess F0A gambiae s.l. susceptibility to pyrethroids. Biochemical Synergist assays were conducted with piperonyl butoxide (PBO), S,S,S-tributyl phosphotritioate, and diethyl maleate. L1014F, L1014S, and N1575Y knockdown resistance (kdr) mutations were investigated using TaqMan genotyping. Results Anopheles gambiae sensu lato was composed of Anopheles arabienisis, Anopheles coluzzii, and A gambiae in all study sites. Anopheles gambiae sensu lato showed a strong phenotypic resistance to deltamethrin and permethrin in all sites (13% to 41% mortality). In many sites, pre-exposure to synergists partially improved the mortality rate suggesting the presence of detoxifying enzymes. The 3 kdr (L1014F, L1014S, and N1575Y) mutations were found, with a predominance of L1014F, in all species. Conclusions Multiple resistance mechanisms to pyrethroids were observed in A gambiae s.l. in Mali. The PBO provided a better partial restoration of susceptibility to pyrethroids, suggesting that the efficacy of long-lasting insecticidal nets may be improved with PBO.
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Affiliation(s)
- Moussa Keïta
- Malaria Research and Training Center, International Center for Excellence in Research, Faculty of Medicine and Odonto Stomatology, University of Sciences, Techniques and Technologies of Bamako, Bamako, Mali
| | - Nafomon Sogoba
- Malaria Research and Training Center, International Center for Excellence in Research, Faculty of Medicine and Odonto Stomatology, University of Sciences, Techniques and Technologies of Bamako, Bamako, Mali
| | - Fousseyni Kané
- Malaria Research and Training Center, International Center for Excellence in Research, Faculty of Medicine and Odonto Stomatology, University of Sciences, Techniques and Technologies of Bamako, Bamako, Mali
| | - Boissé Traoré
- Malaria Research and Training Center, International Center for Excellence in Research, Faculty of Medicine and Odonto Stomatology, University of Sciences, Techniques and Technologies of Bamako, Bamako, Mali
| | - Francis Zeukeng
- The AgroEcohealth Platform, International Institute of Tropical Agriculture (IITA-Benin), Cotonou, Benin
| | - Boubacar Coulibaly
- Malaria Research and Training Center, International Center for Excellence in Research, Faculty of Medicine and Odonto Stomatology, University of Sciences, Techniques and Technologies of Bamako, Bamako, Mali
| | - Ambiélè Bernard Sodio
- Faculty of Science and Technique, University of Sciences, Techniques and Technologies of Bamako, Bamako, Mali
| | - Sekou Fantamady Traoré
- Malaria Research and Training Center, International Center for Excellence in Research, Faculty of Medicine and Odonto Stomatology, University of Sciences, Techniques and Technologies of Bamako, Bamako, Mali
| | - Rousseau Djouaka
- The AgroEcohealth Platform, International Institute of Tropical Agriculture (IITA-Benin), Cotonou, Benin
| | - Seydou Doumbia
- Malaria Research and Training Center, International Center for Excellence in Research, Faculty of Medicine and Odonto Stomatology, University of Sciences, Techniques and Technologies of Bamako, Bamako, Mali
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Tungu PK, Michael E, Sudi W, Kisinza WW, Rowland M. Efficacy of interceptor® G2, a long-lasting insecticide mixture net treated with chlorfenapyr and alpha-cypermethrin against Anopheles funestus: experimental hut trials in north-eastern Tanzania. Malar J 2021; 20:180. [PMID: 33836778 PMCID: PMC8033724 DOI: 10.1186/s12936-021-03716-z] [Citation(s) in RCA: 28] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2021] [Accepted: 03/27/2021] [Indexed: 11/23/2022] Open
Abstract
Background The effectiveness of long-lasting insecticidal nets (LLIN), the primary method for preventing malaria in Africa, is compromised by evolution and spread of pyrethroid resistance. Further gains require new insecticides with novel modes of action. Chlorfenapyr is a pyrrole insecticide that disrupts mitochrondrial function and confers no cross-resistance to neurotoxic insecticides. Interceptor® G2 LN (IG2) is an insecticide-mixture LLIN, which combines wash-resistant formulations of chlorfenapyr and the pyrethroid alpha-cypermethrin. The objective was to determine IG2 efficacy under controlled household-like conditions for personal protection and control of wild, pyrethroid-resistant Anopheles funestus mosquitoes. Methods Experimental hut trials tested IG2 efficacy against two positive controls—a chlorfenapyr-treated net and a standard alpha-cypermethrin LLIN, Interceptor LN (IG1)—consistent with World Health Organization (WHO) evaluation guidelines. Mosquito mortality, blood-feeding inhibition, personal protection, repellency and insecticide-induced exiting were recorded after zero and 20 washing cycles. The trial was repeated and analysed using multivariate and meta-analysis. Results In the two trials held in NE Tanzania, An. funestus mortality was 2.27 (risk ratio 95% CI 1.13–4.56) times greater with unwashed Interceptor G2 than with unwashed Interceptor LN (p = 0.012). There was no significant loss in mortality with IG2 between 0 and 20 washes (1.04, 95% CI 0.83–1.30, p = 0.73). Comparison with chlorfenapyr treated net indicated that most mortality was induced by the chlorfenapyr component of IG2 (0.96, CI 0.74–1.23), while comparison with Interceptor LN indicated blood-feeding was inhibited by the pyrethroid component of IG2 (IG2: 0.70, CI 0.44–1.11 vs IG1: 0.61, CI 0.39–0.97). Both insecticide components contributed to exiting from the huts but the contributions were heterogeneous between trials (heterogeneity Q = 36, P = 0.02). WHO susceptibility tests with pyrethroid papers recorded 44% survival in An. funestus. Conclusions The high mortality recorded by IG2 against pyrethroid-resistant An. funestus provides first field evidence of high efficacy against this primary, anthropophilic, malaria vector.
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Affiliation(s)
- Patrick K Tungu
- Amani Medical Research Centre, National Institute for Medical Research, Muheza, Tanzania. .,Pan-African Malaria Vector Research Consortium (PAMVERC), P.O.Box 81, Muheza, Tanga, Tanzania.
| | - Elisante Michael
- Amani Medical Research Centre, National Institute for Medical Research, Muheza, Tanzania.,Pan-African Malaria Vector Research Consortium (PAMVERC), P.O.Box 81, Muheza, Tanga, Tanzania
| | - Wema Sudi
- Amani Medical Research Centre, National Institute for Medical Research, Muheza, Tanzania.,Pan-African Malaria Vector Research Consortium (PAMVERC), P.O.Box 81, Muheza, Tanga, Tanzania
| | - William W Kisinza
- Amani Medical Research Centre, National Institute for Medical Research, Muheza, Tanzania.,Pan-African Malaria Vector Research Consortium (PAMVERC), P.O.Box 81, Muheza, Tanga, Tanzania
| | - Mark Rowland
- Pan-African Malaria Vector Research Consortium (PAMVERC), P.O.Box 81, Muheza, Tanga, Tanzania.,London School of Hygiene and Tropical Medicine, London, UK
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Dehghankar M, Maleki-Ravasan N, Tahghighi A, Karimian F, Karami M. Bioactivities of rose-scented geranium nanoemulsions against the larvae of Anopheles stephensi and their gut bacteria. PLoS One 2021; 16:e0246470. [PMID: 33556110 PMCID: PMC7870081 DOI: 10.1371/journal.pone.0246470] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2020] [Accepted: 01/19/2021] [Indexed: 11/24/2022] Open
Abstract
Anopheles stephensi with three different biotypes is a major vector of malaria in Asia. It breeds in a wide range of habitats. Therefore, safer and more sustainable methods are needed to control its immature stages rather than chemical pesticides. The larvicidal and antibacterial properties of the Pelargonium roseum essential oil (PREO) formulations were investigated against mysorensis and intermediate forms of An. stephensi in laboratory conditions. A series of nanoemulsions containing different amounts of PREO, equivalent to the calculated LC50 values for each An. stephensi form, and various quantities of surfactants and co-surfactants were developed. The physical and morphological properties of the most lethal formulations were also determined. PREO and its major components, i.e. citronellol (21.34%), L-menthone (6.41%), linalool (4.214%), and geraniol (2.19%), showed potent larvicidal activity against the studied mosquitoes. The LC50/90 values for mysorensis and intermediate forms were computed as 11.44/42.42 ppm and 12.55/47.69 ppm, respectively. The F48/F44 nanoformulations with 94% and 88% lethality for the mysorensis and intermediate forms were designated as optimized formulations. The droplet size, polydispersity index, and zeta-potential for F48/F44 were determined as 172.8/90.95 nm, 0.123/0.183, and -1.08/-2.08 mV, respectively. These results were also confirmed by TEM analysis. Prepared formulations displayed antibacterial activity against larval gut bacteria in the following order of decreasing inhibitory: LC90, optimized nanoemulsions, and LC50. PREO-based formulations were more effective against mysorensis than intermediate. Compared to the crude PREO, the overall larvicidal activity of all nanoformulations boosted by 20% and the optimized formulations by 50%. The sensitivity of insect gut bacteria may be a crucial factor in determining the outcome of the effect of toxins on target insects. The formulations designed in the present study may be a good option as a potent and selective larvicide for An. stephensi.
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Affiliation(s)
- Maryam Dehghankar
- Faculty of Basic Science, Science and Research Branch, Islamic Azad University, Tehran, Iran
- Malaria and Vector Research Group, Biotechnology Research Center, Pasteur Institute of Iran, Tehran, Iran
| | - Naseh Maleki-Ravasan
- Malaria and Vector Research Group, Biotechnology Research Center, Pasteur Institute of Iran, Tehran, Iran
- Department of Parasitology, Pasteur Institute of Iran, Tehran, Iran
- * E-mail: (NMR); (AT)
| | - Azar Tahghighi
- Malaria and Vector Research Group, Biotechnology Research Center, Pasteur Institute of Iran, Tehran, Iran
- Laboratory of Medicinal Chemistry, Department of Clinical Research, Pasteur Institute of Iran, Tehran, Iran
- * E-mail: (NMR); (AT)
| | - Fateh Karimian
- Department of Medical Entomology and Vector Control, School of Public Health, Tehran University of Medical Sciences (TUMS), Tehran, Iran
| | - Mohsen Karami
- Department of Parasitology and Mycology, Babol University of Medical Sciences, Babol, Iran
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Yu JJ, Bong LJ, Panthawong A, Chareonviriyaphap T, Neoh KB. Repellency and Contact Irritancy Responses of Aedes aegypti (Diptera: Culicidae) Against Deltamethrin and Permethrin: A Cross-Regional Comparison. JOURNAL OF MEDICAL ENTOMOLOGY 2021; 58:379-389. [PMID: 32876326 DOI: 10.1093/jme/tjaa172] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/24/2020] [Indexed: 06/11/2023]
Abstract
Control strategies exploiting the innate response of mosquitoes to chemicals are urgently required to complement existing traditional approaches. We therefore examined the behavioral responses of 16 field strains of Aedes aegypti (L.) from two countries, to deltamethrin and permethrin by using an excito-repellency (ER) test system. The result demonstrated that the escape percentage of Ae. aegypti exposed to pyrethroids did not vary significantly between the two countries in both contact and noncontact treatment despite the differing epidemiological patterns. Deltamethrin (contact: 3.57 ± 2.06% to 31.20 ± 10.71%; noncontact: 1.67 ± 1.67% to 17.31 ± 14.85%) elicited relatively lower responses to field mosquitoes when compared with permethrin (contact: 16.15 ± 4.07% to 74.19 ± 4.69%; noncontact: 3.45 ± 2.00% to 41.59 ± 6.98%) in contact and noncontact treatments. Compared with field strains, the mean percentage of escaping laboratory susceptible strain individuals were significantly high after treatments (deltamethrin contact: 72.26 ± 6.95%, noncontact: 61.10 ± 12.31%; permethrin contact: 78.67 ± 9.67%, noncontact: 67.07 ± 7.02%) and the escaped individuals spent significantly shorter time escaping from the contact and noncontact chamber. The results indicated a significant effect of resistance ratio on mean escape percentage, but some strains varied idiosyncratically compared to the increase in insecticide resistance. The results also illustrated that the resistance ratio had a significant effect on the mortality in treatments. However, the mortality in field mosquitoes that prematurely escaped from the treated contact chamber or in mosquitoes that stayed up to the 30-min experimental period showed no significant difference.
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Affiliation(s)
- Jin-Jia Yu
- Department of Entomology, National Chung Hsing University, Taichung, Taiwan
| | - Lee-Jin Bong
- Department of Entomology, National Chung Hsing University, Taichung, Taiwan
| | - Amonrat Panthawong
- Department of Entomology, Faculty of Agriculture, Kasetsart University, Bangkok, Thailand
| | | | - Kok-Boon Neoh
- Department of Entomology, National Chung Hsing University, Taichung, Taiwan
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Influence of a Major Mountainous Landscape Barrier (Mount Cameroon) on the Spread of Metabolic ( GSTe2) and Target-Site ( Rdl) Resistance Alleles in the African Malaria Vector Anopheles funestus. Genes (Basel) 2020; 11:genes11121492. [PMID: 33322524 PMCID: PMC7764057 DOI: 10.3390/genes11121492] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2020] [Revised: 12/05/2020] [Accepted: 12/08/2020] [Indexed: 12/03/2022] Open
Abstract
Increased levels of insecticide resistance in major malaria vectors such as Anopheles funestus threaten the effectiveness of insecticide-based control programmes. Understanding the landscape features impacting the spread of resistance makers is necessary to design suitable resistance management strategies. Here, we examined the influence of the highest mountain in West Africa (Mount Cameroon; 4095 m elevation) on the spread of metabolic and target-site resistance alleles in An. funestus populations. Vector composition varied across the four localities surveyed along the altitudinal cline with major vectors exhibiting high parity rate (80.5%). Plasmodium infection rates ranged from 0.79% (An. melas) to 4.67% (An. funestus). High frequencies of GSTe2R (67–81%) and RdlR (49–90%) resistance alleles were observed in An. funestus throughout the study area, with GSTe2R frequency increasing with altitude, whereas the opposite is observed for RdlR. Patterns of genetic diversity and population structure analyses revealed high levels of polymorphisms with 12 and 16 haplotypes respectively for GSTe2 and Rdl. However, the reduced diversity patterns of resistance allele carriers revealed signatures of positive selection on the two genes across the study area irrespective of the altitude. Despite slight variations associated with the altitude, the spread of resistance alleles suggest that control strategies could be implemented against malaria vectors across mountainous landscapes.
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Kouassi BL, Edi C, Tia E, Konan LY, Akré MA, Koffi AA, Ouattara AF, Tanoh AM, Zinzindohoue P, Kouadio B, Andre M, Irish SR, Armistead J, Dengela D, Cissé NG, Flatley C, Chabi J. Susceptibility of Anopheles gambiae from Côte d'Ivoire to insecticides used on insecticide-treated nets: evaluating the additional entomological impact of piperonyl butoxide and chlorfenapyr. Malar J 2020; 19:454. [PMID: 33298071 PMCID: PMC7725118 DOI: 10.1186/s12936-020-03523-y] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2020] [Accepted: 11/25/2020] [Indexed: 11/29/2022] Open
Abstract
Background Pyrethroid-treated mosquito nets are currently the mainstay of vector control in Côte d’Ivoire. However, resistance to pyrethroids has been reported across the country, limiting options for insecticide resistance management due to the paucity of alternative insecticides. Two types of insecticide-treated nets (ITNs), ITNs with pyrethroids and the synergist piperonyl butoxide (PBO), and Interceptor®G2 nets, a net treated with a combination of chlorfenapyr and alpha-cypermethrin, are believed to help in the control of pyrethroid-resistant mosquitoes. Methods The susceptibility of Anopheles gambiae sensu lato (s.l.) to pyrethroid insecticides with and without pre-exposure to PBO as well as to chlorfenapyr was investigated in fifteen sites across the country. Susceptibility tests were conducted on 2- to 4-day old adult female An. gambiae s.l. reared from larval collections. The resistance status, intensity, and effects of PBO on mortality after exposure to different concentrations of deltamethrin, permethrin and alpha-cypermethrin were determined using WHO susceptibility test kits. In the absence of a WHO-recommended standard protocol for chlorfenapyr, two interim doses (100 and 200 µg/bottle) were used to test the susceptibility of mosquitoes using the CDC bottle assay method. Results Pre-exposure to PBO did not result in full restoration of susceptibility to any of the three pyrethroids for the An. gambiae s.l. populations from any of the sites surveyed. However, PBO pre-exposure did increase mortality for all three pyrethroids, particularly deltamethrin (from 4.4 to 48.9%). Anopheles gambiae s.l. from only one site (Bettie) were susceptible to chlorfenapyr at the dose of 100 µg active ingredient (a.i.)/bottle. At the dose of 200 µg (a.i.)/bottle, susceptibility was only recorded in 10 of the 15 sites. Conclusion Low mosquito mortality was found for pyrethroids alone, and while PBO increased mortality, it did not restore full susceptibility. The vector was not fully susceptible to chlorfenapyr in one third of the sites tested. However, vector susceptibility to chlorfenapyr seems to be considerably higher than for pyrethroids alone or with PBO. These data should be used cautiously when making ITN procurement decisions, noting that bioassays are conducted in controlled conditions and may not fully represent field efficacy where the host-seeking behaviours, which include free-flying activity are known to enhance pro-insecticide chlorfenapyr intoxication to mosquitoes.
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Affiliation(s)
| | - Constant Edi
- Swiss Center of Scientific Research in Côte d'Ivoire, Abidjan, Côte d'Ivoire
| | - Emmanuel Tia
- Centre of Veterinary and Medical Entomology, Abidjan, Côte d'Ivoire
| | - Lucien Y Konan
- National Institute of Public Hygiene, Abidjan, Côte d'Ivoire
| | - Maurice A Akré
- National Institute of Public Health/Pierre Richet Institute, Bouake, Côte d'Ivoire
| | - Alphonsine A Koffi
- National Institute of Public Health/Pierre Richet Institute, Bouake, Côte d'Ivoire
| | | | | | | | - Blaise Kouadio
- U.S. President's Malaria Initiative, USAID, Abidjan, Côte d'Ivoire
| | - McKenzie Andre
- National Malaria Control Programme, Abidjan, Côte d'Ivoire
| | - Seth R Irish
- U.S. President's Malaria Initiative, Entomology Branch, U.S. Centers for Disease Control and Prevention, Atlanta, GA, USA
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Park SH, Jun H, Ahn SK, Lee J, Yu SL, Lee SK, Kang JM, Kim H, Lee HI, Hong SJ, Na BK, Bahk YY, Kim TS. Monitoring Insecticide Resistance and Target Site Mutations of L1014 Kdr And G119 Ace Alleles in Five Mosquito Populations in Korea. THE KOREAN JOURNAL OF PARASITOLOGY 2020; 58:543-550. [PMID: 33202506 PMCID: PMC7672240 DOI: 10.3347/kjp.2020.58.5.543] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Received: 05/30/2020] [Accepted: 09/01/2020] [Indexed: 11/25/2022]
Abstract
Mosquitoes are globally distributed and important vectors for the transmission of many human diseases. Mosquito control is a difficult task and the cost of preventing mosquito-borne diseases is much lower than that for curing the associated diseases. Thus, chemical control remains the most effective tool for mosquito. Due to the long-term intensive use of insecticides to control mosquito vectors, resistance to most chemical insecticides has been reported. This study aimed to investigate the relationship between insecticide resistance and target site mutation of L1014 kdr and G119 ace alleles in 5 species/species group of mosquitoes (Aedes vexans, Ae. albopictus, Anopheles spp., Culex pipiens complex, and Cx. tritaeniorhynchus) obtained from 6 collection sites. For Anopheles spp., the proportion of mosquitoes with mutated alleles in L1014 was 88.4%, homozygous resistant genotypes were observed in 46.7%, and heterozygous resistant genotypes were observed in 41.8%. For the Cx. pipiens complex and Cx. tritaeniorhynchus species, homozygous resistant genotypes were found in 25.9% and 9.8%, respectively. However, target site mutation of L1014 in the Ae. vexans nipponii and Ae. albopictus species was not observed. Anopheles spp., Cx. pipiens complex, and Cx. tritaeniorhynchus mosquitoes were resistant to deltamethrin and chlorpyriphos, whereas Ae. vexans nipponii and Ae. albopictus were clearly susceptible. We also found a correlation between the resistance phenotype and the presence of the L1014 kdr and G119 ace mutations only in the Anopheles spp. population. In this study, we suggest that insecticide resistance poses a growing threat and resistance management must be integrated into all mosquito control programs.
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Affiliation(s)
- Seo Hye Park
- Department of Parasitology and Tropical Medicine & Global Resource Bank of Parasitic Protozoa Pathogens, Inha University School of Medicine, Incheon 22212, Korea
| | - Hojong Jun
- Department of Parasitology and Tropical Medicine & Global Resource Bank of Parasitic Protozoa Pathogens, Inha University School of Medicine, Incheon 22212, Korea
| | - Seong Kyu Ahn
- Department of Parasitology and Tropical Medicine & Global Resource Bank of Parasitic Protozoa Pathogens, Inha University School of Medicine, Incheon 22212, Korea
| | - Jinyoung Lee
- Department of Parasitology and Tropical Medicine & Global Resource Bank of Parasitic Protozoa Pathogens, Inha University School of Medicine, Incheon 22212, Korea
| | - Sung-Lim Yu
- Inha Research Institute for Medical Sciences, Inha University School of Medicine, Incheon 22212, Korea
| | - Sung Keun Lee
- Department of Pharmacology, Inha University School of Medicine, Incheon 22212, Korea
| | - Jung-Mi Kang
- Department of Parasitology and Tropical Medicine, and Institute of Health Sciences, Gyeongsang National University College of Medicine, Jinju 52727, Korea.,Department of Convergence Medical Science, Gyeongsang National University, Jinju 52727, Korea
| | - Hyunwoo Kim
- Division of Vectors and Parasitic Diseases, Korea Centers for Disease Control and Prevention, Osong 28159, Korea
| | - Hee-Il Lee
- Division of Vectors and Parasitic Diseases, Korea Centers for Disease Control and Prevention, Osong 28159, Korea
| | - Sung-Jong Hong
- Department of Medical Environmental Biology, Chung-Ang University College of Medicine, Seoul 06974, Korea
| | - Byoung-Kuk Na
- Department of Parasitology and Tropical Medicine, and Institute of Health Sciences, Gyeongsang National University College of Medicine, Jinju 52727, Korea.,Department of Convergence Medical Science, Gyeongsang National University, Jinju 52727, Korea
| | - Young Yil Bahk
- Department of Biotechnology, College of Biomedical and Health Science, Konkuk University, Chungju 27478, Korea
| | - Tong-Soo Kim
- Department of Parasitology and Tropical Medicine & Global Resource Bank of Parasitic Protozoa Pathogens, Inha University School of Medicine, Incheon 22212, Korea
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St Clair CR, Norris EJ, Masloski KE, Coats JR, Gassmann AJ. Evaluation of pyrethroids and organophosphates in insecticide mixtures for management of western corn rootworm larvae. PEST MANAGEMENT SCIENCE 2020; 76:3871-3878. [PMID: 32501631 DOI: 10.1002/ps.5938] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/13/2020] [Revised: 05/14/2020] [Accepted: 06/05/2020] [Indexed: 06/11/2023]
Abstract
BACKGROUND The western corn rootworm is an economically important pest of corn. Management tactics include pyrethroid and organophosphate insecticides, which may be applied as a mixture to protect corn roots. The goal of our study was to characterize the effects of pyrethroids and organophosphates alone and in combination on larval corn rootworm mortality and injury to corn roots. We evaluated two insecticide combinations: tebupirimphos with β-cyfluthrin and chlorethoxyfos with bifenthrin. Using a soil-based, laboratory bioassay, we exposed larvae to five concentrations of the pyrethroid alone, the organophosphate alone, the combined formulation, and a water control. We calculated LC50 values and co-toxicity factors to determine synergism or antagonism between organophosphates and pyrethroids. We also measured adult emergence and root injury in a field experiment that tested tebupirimphos alone, β-cyfluthrin alone, the combined formulation, and an untreated control. RESULTS Bioassay results indicated antagonism between the pyrethroid and organophosphate at most concentrations for both insecticide combinations. In the field experiment, tebupirimphos alone or in combination with β-cyfluthrin significantly reduced adult emergence and root injury compared to the untreated controls, but β-cyfluthrin alone did not differ from the untreated control for either metric. CONCLUSIONS These results suggest that, at the concentrations tested, the pyrethroid component of pyrethroid-organophosphate mixtures may not contribute to a reduction of rootworm emergence or root injury. While these pyrethroids may confer a management benefit for other pests, such as seedcorn maggot, the concentrations of pyrethroids present in current formulations of these mixtures are likely too low for effective rootworm management. © 2020 Society of Chemical Industry.
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Affiliation(s)
- Coy R St Clair
- Department of Entomology, Iowa State University, Ames, IA, USA
| | - Edmund J Norris
- Emerging Pathogens Institute, University of Florida, Gainesville, FL, USA
| | - Kenneth E Masloski
- Department of Entomology, Texas A&M University, College Station, TX, USA
| | - Joel R Coats
- Department of Entomology, Iowa State University, Ames, IA, USA
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40
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Enayati A, Hanafi-Bojd AA, Sedaghat MM, Zaim M, Hemingway J. Evolution of insecticide resistance and its mechanisms in Anopheles stephensi in the WHO Eastern Mediterranean Region. Malar J 2020; 19:258. [PMID: 32680514 PMCID: PMC7367398 DOI: 10.1186/s12936-020-03335-0] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2020] [Accepted: 07/13/2020] [Indexed: 11/29/2022] Open
Abstract
BACKGROUND While Iran is on the path to eliminating malaria, the disease with 4.9 million estimated cases and 9300 estimated deaths in 2018 remains a serious health problem in the World Health Organization (WHO) Eastern Mediterranean Region. Anopheles stephensi is the main malaria vector in Iran and its range extends from Iraq to western China. Recently, the vector invaded new territories in Sri Lanka and countries in the Horn of Africa. Insecticide resistance in An. stephensi is a potential issue in controlling the spread of this vector. METHODS Data were collated from national and international databases, including PubMed, Google Scholar, Scopus, ScienceDirect, SID, and IranMedex using appropriate search terms. RESULTS Indoor residual spaying (IRS) with DDT was piloted in Iran in 1945 and subsequently used in the malaria eradication programme. Resistance to DDT in An. stephensi was detected in Iran, Iraq, Pakistan, and Saudi Arabia in the late 1960s. Malathion was used for malaria control in Iran in 1967, then propoxur in 1978, followed by pirimiphos-methyl from 1992 to 1994. The pyrethroid insecticide lambda-cyhalothrin was used from 1994 to 2003 followed by deltamethrin IRS and long-lasting insecticidal nets (LLINs). Some of these insecticides with the same sequence were used in other malaria-endemic countries of the region. Pyrethroid resistance was detected in An. stephensi in Afghanistan in 2010, in 2011 in India and in 2012 in Iran. The newly invaded population of An. stephensi in Ethiopia was resistant to insecticides of all four major insecticide classes. Different mechanisms of insecticide resistance, including metabolic and insecticide target site insensitivity, have been developed in An. stephensi. Resistance to DDT was initially glutathione S-transferase based. Target site knockdown resistance was later selected by pyrethroids. Esterases and altered acetylcholinesterase are the underlying cause of organophosphate resistance and cytochrome p450s were involved in pyrethroid metabolic resistance. CONCLUSIONS Anopheles stephensi is a major malaria vector in Iran and many countries in the region and beyond. The species is leading in terms of development of insecticide resistance as well as developing a variety of resistance mechanisms. Knowledge of the evolution of insecticide resistance and their underlying mechanisms, in particular, are important to Iran, considering the final steps the country is taking towards malaria elimination, but also to other countries in the region for their battle against malaria. This systematic review may also be of value to countries and territories newly invaded by this species, especially in the Horn of Africa, where the malaria situation is already dire.
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Affiliation(s)
- Ahmadali Enayati
- Department of Medical Entomology and Vector Control, School of Public Health and Health Sciences Research Center, Mazandaran University of Medical Sciences, Sari, Iran
| | - Ahmad Ali Hanafi-Bojd
- Department of Medical Entomology and Vector Control, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran
| | - Mohammad Mehdi Sedaghat
- Department of Medical Entomology and Vector Control, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran
| | - Morteza Zaim
- Department of Medical Entomology and Vector Control, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran.
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Chanda J, Saili K, Phiri F, Stevenson JC, Mwenda M, Chishimba S, Mulube C, Mambwe B, Lungu C, Earle D, Bennett A, Eisele TP, Kamuliwo M, Steketee RW, Keating J, Miller JM, Sikaala CH. Pyrethroid and Carbamate Resistance in Anopheles funestus Giles along Lake Kariba in Southern Zambia. Am J Trop Med Hyg 2020; 103:90-97. [PMID: 32618244 PMCID: PMC7416976 DOI: 10.4269/ajtmh.19-0664] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Whereas data on insecticide resistance and its underlying mechanisms exist for parts of Zambia, data remain limited in the southern part of the country. This study investigated the status of insecticide resistance, metabolic mechanisms, and parasite infection in Anopheles funestus along Lake Kariba in southern Zambia. Indoor-resting mosquitoes were collected from 20 randomly selected houses within clusters where a mass drug administration trial was conducted and raised to F1 progeny. Non–blood-fed 2- to 5-day-old female An. funestus were exposed to WHO insecticide-impregnated papers with 0.05% deltamethrin, 0.1% bendiocarb, 0.25% pirimiphos-methyl, or 4% dichloro-diphenyl-trichloroethane (DDT). In separate assays, An. funestus were pre-exposed to piperonyl butoxide (PBO) to determine the presence of monooxygenases. Wild-caught An. funestus that had laid eggs for susceptibility assays were screened for circumsporozoite protein of Plasmodium falciparum by ELISA, and sibling species were identified by polymerase chain reaction. Anopheles funestus showed resistance to deltamethrin and bendiocarb but remained susceptible to pirimiphos-methyl and DDT. The pre-exposure of An. funestus to PBO restored full susceptibility to deltamethrin but not to bendiocarb. The overall sporozoite infection rate in An. funestus populations was 5.8%. Detection of pyrethroid and carbamate resistance in An. funestus calls for increased insecticide resistance monitoring to guide planning and selection of effective insecticide resistance management strategies. To prevent the development of resistance and reduce the underlying vectorial capacity of mosquitoes in areas targeted for malaria elimination, an effective integrated vector management strategy is needed.
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Affiliation(s)
- Javan Chanda
- PATH Malaria Control and Elimination Partnership in Africa (MACEPA), Lusaka, Zambia
| | - Kochelani Saili
- PATH Malaria Control and Elimination Partnership in Africa (MACEPA), Lusaka, Zambia
| | - Foustina Phiri
- National Malaria Elimination Centre, Zambia Ministry of Health, Lusaka, Zambia
| | - Jennifer C Stevenson
- W. Harry Feinstone Department of Molecular Microbiology and Immunology, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland.,Macha Research Trust, Choma, Zambia
| | - Mulenga Mwenda
- PATH Malaria Control and Elimination Partnership in Africa (MACEPA), Lusaka, Zambia
| | - Sandra Chishimba
- PATH Malaria Control and Elimination Partnership in Africa (MACEPA), Lusaka, Zambia
| | - Conceptor Mulube
- PATH Malaria Control and Elimination Partnership in Africa (MACEPA), Lusaka, Zambia
| | - Brenda Mambwe
- PATH Malaria Control and Elimination Partnership in Africa (MACEPA), Lusaka, Zambia
| | - Christopher Lungu
- PATH Malaria Control and Elimination Partnership in Africa (MACEPA), Lusaka, Zambia
| | - Duncan Earle
- PATH Malaria Control and Elimination Partnership in Africa (MACEPA), Lusaka, Zambia
| | - Adam Bennett
- Malaria Elimination Initiative, Global Health Group, University of California San Francisco, San Francisco, California
| | - Thomas P Eisele
- Department of Tropical Medicine, Center for Applied Malaria Research and Evaluation, Tulane University School of Public Health and Tropical Medicine, New Orleans, Louisiana
| | - Mulakwa Kamuliwo
- National Malaria Elimination Centre, Zambia Ministry of Health, Lusaka, Zambia
| | | | - Joseph Keating
- Department of Tropical Medicine, Center for Applied Malaria Research and Evaluation, Tulane University School of Public Health and Tropical Medicine, New Orleans, Louisiana
| | - John M Miller
- PATH Malaria Control and Elimination Partnership in Africa (MACEPA), Lusaka, Zambia
| | - Chadwick H Sikaala
- SADC Malaria Elimination Eight Secretariat, Windhoek, Namibia.,National Malaria Elimination Centre, Zambia Ministry of Health, Lusaka, Zambia
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Staedke SG, Gonahasa S, Dorsey G, Kamya MR, Maiteki-Sebuguzi C, Lynd A, Katureebe A, Kyohere M, Mutungi P, Kigozi SP, Opigo J, Hemingway J, Donnelly MJ. Effect of long-lasting insecticidal nets with and without piperonyl butoxide on malaria indicators in Uganda (LLINEUP): a pragmatic, cluster-randomised trial embedded in a national LLIN distribution campaign. Lancet 2020; 395:1292-1303. [PMID: 32305094 PMCID: PMC7181182 DOI: 10.1016/s0140-6736(20)30214-2] [Citation(s) in RCA: 87] [Impact Index Per Article: 21.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/21/2019] [Revised: 01/16/2020] [Accepted: 01/24/2020] [Indexed: 12/13/2022]
Abstract
BACKGROUND Long-lasting insecticidal nets (LLINs) are the primary malaria prevention tool, but their effectiveness is threatened by pyrethroid resistance. We embedded a pragmatic cluster-randomised trial into Uganda's national LLIN campaign to compare conventional LLINs with those containing piperonyl butoxide (PBO), a synergist that can partially restore pyrethroid susceptibility in mosquito vectors. METHODS 104 health sub-districts, from 48 districts in Uganda, were randomly assigned to LLINs with PBO (PermaNet 3.0 and Olyset Plus) and conventional LLINs (PermaNet 2.0 and Olyset Net) by proportionate randomisation using an iterative process. At baseline 6, 12, and 18 months after LLIN distribution, cross-sectional surveys were done in 50 randomly selected households per cluster (5200 per survey); a subset of ten households per cluster (1040 per survey) were randomly selected for entomological surveys. The primary outcome was parasite prevalence by microscopy in children aged 2-10 years, assessed in the as-treated population at 6, 12, and 18 months. This trial is registered with ISRCTN, ISRCTN17516395. FINDINGS LLINs were delivered to households from March 25, 2017, to March 18, 2018, 32 clusters were randomly assigned to PermaNet 3.0, 20 to Olyset Plus, 37 to PermaNet 2.0, and 15 to Olyset Net. In the as-treated analysis, three clusters were excluded because no dominant LLIN was received, and four clusters were reassigned, resulting in 49 PBO LLIN clusters (31 received PermaNet 3.0 and 18 received Olyset Plus) and 52 non-PBO LLIN clusters (39 received PermaNet 2.0 and 13 received Olyset Net). At 6 months, parasite prevalence was 11% (386/3614) in the PBO group compared with 15% (556/3844) in the non-PBO group (prevalence ratio [PR] adjusted for baseline values 0·74, 95% CI 0·62-0·87; p=0·0003). Parasite prevalence was similar at month 12 (11% vs 13%; PR 0·73, 95% CI 0·63-0·85; p=0·0001) and month 18 (12% vs 14%; PR 0·84, 95% CI 0·72-0·98; p=0·029). INTERPRETATION In Uganda, where pyrethroid resistance is high, PBO LLINs reduced parasite prevalence more effectively than did conventional LLINs for up to 18 months. This study provides evidence needed to support WHO's final recommendation on use of PBO LLINs. FUNDING The Against Malaria Foundation, UK Department for International Development, Innovative Vector Control Consortium, and Bill and Melinda Gates Foundation.
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Affiliation(s)
- Sarah G Staedke
- Department of Clinical Research, London School of Hygiene & Tropical Medicine, London, UK; Infectious Diseases Research Collaboration, Kampala, Uganda.
| | | | - Grant Dorsey
- Department of Medicine, University of California, San Francisco, CA, USA
| | - Moses R Kamya
- Infectious Diseases Research Collaboration, Kampala, Uganda; Department of Medicine, Makerere University, Kampala, Uganda
| | | | - Amy Lynd
- Department of Vector Biology, Liverpool School of Tropical Medicine, Liverpool, UK
| | | | - Mary Kyohere
- Infectious Diseases Research Collaboration, Kampala, Uganda
| | - Peter Mutungi
- Infectious Diseases Research Collaboration, Kampala, Uganda
| | - Simon P Kigozi
- Infectious Diseases Research Collaboration, Kampala, Uganda
| | - Jimmy Opigo
- National Malaria Control Division, Ministry of Health, Kampala, Uganda
| | - Janet Hemingway
- Department of Vector Biology, Liverpool School of Tropical Medicine, Liverpool, UK
| | - Martin J Donnelly
- Department of Vector Biology, Liverpool School of Tropical Medicine, Liverpool, UK; Wellcome Sanger Institute, Hinxton, UK
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Distribution of Anopheles mosquito species, their vectorial role and profiling of knock-down resistance mutations in Botswana. Parasitol Res 2020; 119:1201-1208. [DOI: 10.1007/s00436-020-06614-6] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2019] [Accepted: 01/22/2020] [Indexed: 01/21/2023]
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Manwill PK, Kalsi M, Wu S, Martinez Rodriguez EJ, Cheng X, Piermarini PM, Rakotondraibe HL. Semi-synthetic cinnamodial analogues: Structural insights into the insecticidal and antifeedant activities of drimane sesquiterpenes against the mosquito Aedes aegypti. PLoS Negl Trop Dis 2020; 14:e0008073. [PMID: 32101555 PMCID: PMC7062286 DOI: 10.1371/journal.pntd.0008073] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2019] [Revised: 03/09/2020] [Accepted: 01/18/2020] [Indexed: 11/28/2022] Open
Abstract
The Aedes aegypti mosquito serves as a major vector for viral diseases, such as dengue, chikungunya, and Zika, which are spreading across the globe and threatening public health. In addition to increased vector transmission, the prevalence of insecticide-resistant mosquitoes is also on the rise, thus solidifying the need for new, safe and effective insecticides to control mosquito populations. We recently discovered that cinnamodial, a unique drimane sesquiterpene dialdehyde of the Malagasy medicinal plant Cinnamosma fragrans, exhibited significant larval and adult toxicity to Ae. aegypti and was more efficacious than DEET-the gold standard for insect repellents-at repelling adult female Ae. aegypti from blood feeding. In this study several semi-synthetic analogues of cinnamodial were prepared to probe the structure-activity relationship (SAR) for larvicidal, adulticidal and antifeedant activity against Ae. aegypti. Initial efforts were focused on modification of the dialdehyde functionality to produce more stable active analogues and to understand the importance of the 1,4-dialdehyde and the α,ß-unsaturated carbonyl in the observed bioactivity of cinnamodial against mosquitoes. This study represents the first investigation into the SAR of cinnamodial as an insecticide and antifeedant against the medically important Ae. aegypti mosquito.
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Affiliation(s)
- Preston K. Manwill
- Division of Medicinal Chemistry and Pharmacognosy, College of Pharmacy, The Ohio State University, Columbus, Ohio, United States of America
- Center for Applied Plant Sciences, The Ohio State University, Columbus, Ohio, United States of America
| | - Megha Kalsi
- Department of Entomology, The Ohio State University, Ohio Agricultural Research and Development Center, Wooster, Ohio, United States of America
| | - Sijin Wu
- Division of Medicinal Chemistry and Pharmacognosy, College of Pharmacy, The Ohio State University, Columbus, Ohio, United States of America
| | - Erick J. Martinez Rodriguez
- Department of Entomology, The Ohio State University, Ohio Agricultural Research and Development Center, Wooster, Ohio, United States of America
| | - Xiaolin Cheng
- Division of Medicinal Chemistry and Pharmacognosy, College of Pharmacy, The Ohio State University, Columbus, Ohio, United States of America
| | - Peter M. Piermarini
- Center for Applied Plant Sciences, The Ohio State University, Columbus, Ohio, United States of America
- Department of Entomology, The Ohio State University, Ohio Agricultural Research and Development Center, Wooster, Ohio, United States of America
| | - Harinantenaina L. Rakotondraibe
- Division of Medicinal Chemistry and Pharmacognosy, College of Pharmacy, The Ohio State University, Columbus, Ohio, United States of America
- Center for Applied Plant Sciences, The Ohio State University, Columbus, Ohio, United States of America
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Bayili K, N’Do S, Yadav RS, Namountougou M, Ouattara A, Dabiré RK, Ouédraogo GA, Diabaté A. Experimental hut evaluation of DawaPlus 3.0 LN and DawaPlus 4.0 LN treated with deltamethrin and PBO against free-flying populations of Anopheles gambiae s.l. in Vallée du Kou, Burkina Faso. PLoS One 2019; 14:e0226191. [PMID: 31869350 PMCID: PMC6927612 DOI: 10.1371/journal.pone.0226191] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2019] [Accepted: 11/21/2019] [Indexed: 11/18/2022] Open
Abstract
Background In view of widespread pyrethroid resistance in malaria vectors in Africa, two long-lasting insecticidal nets (LLINs) incorporated with a synergist, piperonyl butoxide (PBO), DawaPlus 3.0 (deltamethrin + PBO in the roof panel; deltamethrin alone in the side panels) and DawaPlus 4.0 (deltamethrin + PBO in all panels), were evaluated in an experimental hut trial in a rice growing irrigated area in Burkina Faso. Efficacy of nets was tested against free-flying malaria vector, Anopheles gambiae s.l., with high pyrethroid resistance involving L1014F kdr and CYP6P3P450 resistance mechanisms. Methodology The efficacy of unwashed and 20-times washed DawaPlus 3.0 (polyethylene roof panel with 120 mg/m2 deltamethrin and 440 mg/m2 PBO; polyester side panels with deltamethrin 100 mg/m2) and DawaPlus 4.0 (same composition as roof of DawaPlus 3.0) was evaluated against DawaPlus 2.0 (80 mg/m2 deltamethrin; positive control). Volunteer sleepers and treatments were rotated in huts using a Latin square design on 63 consecutive nights during August–October 2016. Mortality, human blood-feeding inhibition, deterrence and exit rates of An. gambiae s.l. were monitored. Principal findings Significantly higher rates of mortality and blood-feeding inhibition were observed with unwashed DawaPlus 4.0 (36%; 47.5%) than unwashed DawaPlus 3.0 (11.8%; 33.3%), DawaPlus 2.0 (4.3%; 6.4%) or untreated net (P < 0.05). Washing reduced personal protective efficacy yet PBO-LLINs were more protective and both met the WHO criteria. Conclusions The PBO-containing DawaPlus 4.0 significantly protected against An. gambiae s.l. in the study area. Unwashed DawaPlus 3.0 gave low to moderate protection against the positive control. PBO inhibits oxidase action; hence in areas with active malaria transmission having oxidase mechanisms, PBO nets could confer additional personal protection.
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Affiliation(s)
- Koama Bayili
- Institut de Recherche en Sciences de la Santé/Centre Muraz, Bobo-Dioulasso, Burkina Faso
- Université Nazi Boni, Bobo-Dioulasso, Burkina Faso
- * E-mail: (KB); (AD)
| | - Sévérin N’Do
- Institut de Recherche en Sciences de la Santé/Centre Muraz, Bobo-Dioulasso, Burkina Faso
| | - Rajpal S. Yadav
- Vector Ecology and Management, Department of Control of Neglected Tropical Diseases, World Health Organization, Geneva, Switzerland
| | - Moussa Namountougou
- Institut de Recherche en Sciences de la Santé/Centre Muraz, Bobo-Dioulasso, Burkina Faso
- Université Nazi Boni, Bobo-Dioulasso, Burkina Faso
| | - Abdoulaye Ouattara
- Institut de Recherche en Sciences de la Santé/Centre Muraz, Bobo-Dioulasso, Burkina Faso
| | - Roch K. Dabiré
- Institut de Recherche en Sciences de la Santé/Centre Muraz, Bobo-Dioulasso, Burkina Faso
| | | | - Abdoulaye Diabaté
- Institut de Recherche en Sciences de la Santé/Centre Muraz, Bobo-Dioulasso, Burkina Faso
- * E-mail: (KB); (AD)
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Age- and sex-related ABC transporter expression in pyrethroid-susceptible and -resistant Aedes aegypti. Sci Rep 2019; 9:19551. [PMID: 31862982 PMCID: PMC6925122 DOI: 10.1038/s41598-019-56134-2] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2019] [Accepted: 11/22/2019] [Indexed: 12/14/2022] Open
Abstract
Resistance mechanisms to synthetic insecticides often include point mutations and increased expression of genes encoding detoxification enzymes. Since pyrethroids are the main adulticides used against Aedes aegypti, which vectors pathogens such as Zika virus, understanding resistance to this insecticide class is of significant relevance. We focused on adenosine triphosphate (ATP)-binding cassette (ABC) transporters in the pyrethroid-resistant Puerto Rico (PR) strain of Ae. aegypti. We investigated the expression patterns of six ABC transporters previously characterized as differentially expressed in insecticide-challenged mosquitoes, or increased mRNA expression in pyrethroid-resistant Ae. aegypti, by comparing PR to the Rockefeller (Rock) susceptible strain. No constitutive differential expression between strains was detected, but expression differences for these genes was influenced by sex and age, suggesting that their role is independent from resistance in PR. Instead, ABC transporters may be induced after insecticide exposure. Challenging mosquitoes with deltamethrin, with or without ABC transporter modulators, showed that Rock and PR responded differently, but a contribution of ABC transporters to deltamethrin toxicity is suspected. Moreover, the effect of dexamethasone, which enhanced the inhibition of nerve firing by deltamethrin, was observed using a Drosophila central nervous system preparation, showing synergy of these two compounds through the potential inhibition of ABC transporters.
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Chatha SAS, Asgher M, Asgher R, Hussain AI, Iqbal Y, Hussain SM, Bilal M, Saleem F, Iqbal HMN. Environmentally responsive and anti-bugs textile finishes - Recent trends, challenges, and future perspectives. THE SCIENCE OF THE TOTAL ENVIRONMENT 2019; 690:667-682. [PMID: 31301507 DOI: 10.1016/j.scitotenv.2019.06.520] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/23/2019] [Revised: 06/24/2019] [Accepted: 06/30/2019] [Indexed: 02/08/2023]
Abstract
Bugs, such as microorganisms and insects, are present in the environment and sometimes can be health-hazardous if the living environment is not maintained following proper hygienic regulations. In the present scenario of increasing public awareness, environmental consciousness, and growing demand for easy-care, and disinfected textiles, the manufacturing of protective and easy-to-care textiles has become a key necessity of the modern world. Comfortable, clean, hygienic, antimicrobial, and insect repelling properties of textile goods are gaining the accelerating research momentum as a basic requirement to produce multifunctional textiles. These functional finishes have numerous applications such as in-home textiles, bed nets, and tenting, camping gear as well as in military uniforms. Synthetic antimicrobial and insect repellents are quite effective against insects and microscopic organisms but are slightly toxic to the human being and the environment. To overcome these problems, researchers are considering natural agents for functional finishes, but their effectiveness is less durable to textile material. Besides needful advantages, the excessive use of dyes in finishing processes heavily required washing cycles and ultimately release various types of hazardous dyes or wasteful effluents in the environment. This review reports the chemical composition and recent developments in textile finishes, particularly antimicrobial and insect repellent textile finishes. A large number of commonly used antimicrobial agents (i.e. chitosan, zwitterionic compounds, silver and silver-based compounds, titanium dioxide nanoparticles, imidazolium salts, triclosan and quaternary ammonium salts) and insect repellent textile finishes (i.e. N‑N‑diethyl‑m‑toluamide, permethrin, cypermethrin, pyrethrum, picaridin, bioallethrin, citriodiol and essential oils) have been presented. Finally, the review is wrapped up with major research gaps/challenges, concluding remarks, and future opportunities in this area of research.
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Affiliation(s)
| | - Muhammad Asgher
- Department of Biochemistry, University of Agriculture Faisalabad, Pakistan
| | - Rabbia Asgher
- Department of Chemistry, University of Agriculture, Faisalabad 38030, Pakistan
| | | | - Yasir Iqbal
- Department of Chemistry, Government College University Faisalabad, 38000, Pakistan
| | | | - Muhammad Bilal
- School of Life Science and Food Engineering, Huaiyin Institute of Technology, Huaian 223003, China.
| | - Faizan Saleem
- Department of Chemistry, Government College University Faisalabad, 38000, Pakistan
| | - Hafiz M N Iqbal
- Tecnologico de Monterrey, School of Engineering and Sciences, Campus Monterrey, Ave. Eugenio Garza Sada 2501, Monterrey, N.L. CP 64849, Mexico.
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Philbert A, Lyantagaye SL, Nkwengulila G. Farmers' pesticide usage practices in the malaria endemic region of North-Western Tanzania: implications to the control of malaria vectors. BMC Public Health 2019; 19:1456. [PMID: 31694595 PMCID: PMC6833290 DOI: 10.1186/s12889-019-7767-0] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2018] [Accepted: 10/11/2019] [Indexed: 11/21/2022] Open
Abstract
Background Pesticides remain the mainstay for the control of agricultural pests and disease vectors. However, their indiscriminate use in agriculture has led to development of resistance to both crop pests and disease vectors. This threatens to undermine the success gained through the implementation of chemical based vector control programs. We investigated the practices of farmers with regard to pesticide usage in the vegetable growing areas and their impact on susceptibility status of An. gambiae s.l. Methods A stratified multistage sampling technique using the administrative structure of the Tanzanian districts as sampling frame was used. Wards, villages and then participants with farms where pesticides are applied were purposively recruited at different stages of the process, 100 participants were enrolled in the study. The same villages were used for mosquito larvae sampling from the farms and the surveys were complimented by the entomological study. Larvae were reared in the insectary and the emerging 2–3 days old female adults of Anopheles gambiae s.l were subjected to susceptibility test. Results Forty eight pesticides of different formulations were used for control of crop and Livestock pests. Pyrethroids were the mostly used class of pesticides (50%) while organophosphates and carbamates were of secondary importance. Over 80% of all farmers applied pesticides in mixed form. Susceptibility test results confirmed high phenotypic resistance among An. gambiae populations against DDT and the pyrethroids (Permethrin-0.75%, Cyfluthrin-0.15%, Deltametrin-0.05% and Lambdacyhalothrin-0.05%) with mortality rates 54, 61, 76 and 71%, respectively. Molecular analysis showed An. arabiensis as a dominant species (86%) while An. gambiae s.s constituted only 6%. The kdr genes were not detected in all of the specimens that survived insecticide exposures. Conclusion The study found out that there is a common use of pyrethroids in farms, Livestocks as well as in public health. The study also reports high phenotypic resistance among An. gambiae s.l against most of the pyrethroids tested. The preponderance of pyrethroids in agriculture is of public health concern because this is the class of insecticides widely used in vector control programs and this calls for combined integrated pest and vector management (IPVM).
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Affiliation(s)
- Anitha Philbert
- Department of Zoology and Wildlife Conservation, University of Dar es Salaam, Dar es Salaam, Tanzania.
| | | | - Gamba Nkwengulila
- Department of Zoology and Wildlife Conservation, University of Dar es Salaam, Dar es Salaam, Tanzania
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Mulatier M, Pennetier C, Porciani A, Chandre F, Dormont L, Cohuet A. Prior contact with permethrin decreases its irritancy at the following exposure among a pyrethroid-resistant malaria vector Anopheles gambiae. Sci Rep 2019; 9:8177. [PMID: 31160750 PMCID: PMC6546682 DOI: 10.1038/s41598-019-44633-1] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2019] [Accepted: 05/21/2019] [Indexed: 11/26/2022] Open
Abstract
Insecticide-treated nets (ITNs) remain major components for vector control despite the spread of resistance mechanisms among mosquito populations. Multiple exposures to pyrethroids may induce physiological and behavioral changes in mosquitoes, possibly reducing efficacy of control tools. Despite epidemiological relevance, the effects of multiple exposures to pyrethroids on their efficacy against pyrethroid-resistant mosquitoes has received little interest. In the present study, we assessed the effects of a blood-meal successfully obtained upon a permethrin-treated net on the success at taking a second blood-meal in presence of permethrin in Anopheles gambiae, carrying pyrethroid resistance alleles. We also measured the impact of exposure to permethrin on life-history traits to address the delayed efficacy of ITNs. Our results showed that females that successfully blood-fed upon a permethrin-treated net were no longer inhibited by permethrin at the following exposure. Blood-meal inhibition due to permethrin was not affected by female size nor by exposure of mothers when testing the offspring, allowing to discard the effect of genetic or physiological selection. Besides, in our assays, exposure to permethrin did not affect mosquito fecundity, fertility nor survival. These results give insights to understand the long-term efficacy of ITNs, and allow to reevaluate the criteria used when choosing compounds for fighting malaria mosquitoes.
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Affiliation(s)
- Margaux Mulatier
- MIVEGEC, IRD, CNRS, Univ. Montpellier, Montpellier, France. .,CEFE, Univ Paul Valéry Montpellier 3, CNRS, Univ Montpellier, EPHE, IRD, Montpellier, France.
| | - Cédric Pennetier
- MIVEGEC, IRD, CNRS, Univ. Montpellier, Montpellier, France.,Institut Pierre Richet, Bouaké, Côte d'Ivoire
| | | | | | - Laurent Dormont
- CEFE, Univ Paul Valéry Montpellier 3, CNRS, Univ Montpellier, EPHE, IRD, Montpellier, France
| | - Anna Cohuet
- Institut Pierre Richet, Bouaké, Côte d'Ivoire
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Abstract
BACKGROUND Insecticide-treated nets (ITNs) and indoor residual spraying (IRS) are used to control malaria vectors. Both strategies use insecticides to kill mosquitoes that bite and rest indoors. For ITNs, the World Health Organization (WHO) only recommended pyrethroids until 2018, but mosquito vectors are becoming resistant to this insecticide. For IRS, a range of insecticides are recommended. Adding IRS to ITNs may improve control, simply because two interventions may be better than one; it may improve malaria control where ITNs are failing due to pyrethroid resistance; and it may slow the emergence and spread of pyrethroid resistance. OBJECTIVES To summarize the effect on malaria of additionally implementing IRS, using non-pyrethroid-like or pyrethroid-like insecticides, in communities currently using ITNs. SEARCH METHODS We searched the Cochrane Infectious Diseases Group Specialized Register; the Cochrane Central Register of Controlled Trials (CENTRAL); MEDLINE; Embase; LILACS; the WHO International Clinical Trials Registry Platform; ClinicalTrials.gov; and the ISRCTN registry up to 18 March 2019. SELECTION CRITERIA Cluster-randomized controlled trials (cRCTs), interrupted time series (ITS), or controlled before-and-after studies (CBAs) comparing IRS plus ITNs with ITNs alone. DATA COLLECTION AND ANALYSIS Two review authors independently assessed trials for eligibility, analyzed risk of bias, and extracted data. We used risk ratio (RR) and 95% confidence intervals (CI). We stratified by type of insecticide: 'non-pyrethroid-like', as this could improve malaria control better than adding IRS insecticides that have the same way of working as the insecticide on ITNs ('pyrethroid-like'). We used subgroup analysis of ITN usage in the trials to explore heterogeneity. We assessed the certainty of evidence using the GRADE approach. MAIN RESULTS Six cRCTs (eight comparisons) met our inclusion criteria conducted since 2008 in sub-Saharan Africa. Malaria transmission in all sites was from mosquitoes belonging to the Anopheles gambiae s.l. complex species; two trials in Benin and Tanzania also reported the vector Anopheles funestus. Three trials used insecticide with targets different to pyrethroids (two used bendiocarb and one used pirimiphos-methyl); two trials used dichloro-diphenyl-trichlorethane (DDT), an insecticide with the same target as pyrethroids; and one trial used both types of insecticide (pyrethroid deltamethrin in the first year, switching to bendiocarb for the second-year). ITN usage was greater than 50% in three trials, and less than 50% in the remainder.Indoor residual spraying using 'non-pyrethroid-like' insecticides Adding IRS with a non-pyrethroid-like insecticide had mixed results. Overall, we do not know if the addition of IRS impacted on malaria incidence (rate ratio 0.93, 95% CI 0.46 to 1.86; 2 cRCTs, 566 child-years; very low-certainty evidence); it may have reduced malaria parasite prevalence (0.67, 95% CI 0.35 to 1.28; 5 comparisons from 4 cRCTs, 10,440 participants; low-certainty evidence); and it may have reduced the prevalence of anaemia (RR CI 0.46, 95% 0.18 to 1.20; 3 comparisons from 2 cRCTs, 2026 participants; low-certainty evidence). Three trials reported the impact on EIR, with variable results; overall, we do not know if IRS had any effect on the EIR in communities using ITNs (very low-certainty evidence). Trials also reported the adult mosquito density and the sporozoite rate, but we could not summarize or pool these entomological outcomes due to unreported data. ITN usage did not explain the variation in malaria outcomes between different studies. One trial reported no effect on malaria incidence or parasite prevalence in the first year, when the insecticide used for IRS had the same target as pyrethroids, but showed an effect on both outcomes in the second year, when the insecticide was replaced by one with a different target.Two trials measured the prevalence of pyrethroid resistance before and after IRS being introduced: no difference was detected, but these data are limited.Indoor residual spraying using 'pyrethroid-like' insecticidesAdding IRS using a pyrethroid-like insecticide did not appear to markedly alter malaria incidence (rate ratio 1.07, 95% CI 0.80 to 1.43; 2 cRCTs, 15,717 child-years; moderate-certainty evidence), parasite prevalence (RR 1.11, 95% CI 0.86 to 1.44; 3 cRCTs, 10,820 participants; moderate-certainty evidence), or anaemia prevalence (RR 1.12, 95% CI 0.89 to 1.40; 1 cRCT, 4186 participants; low-certainty evidence). Data on the entomological inoculation rate (EIR) were limited, and therefore we do not know if IRS had any effect on the EIR in communities using ITNs (very low-certainty evidence). AUTHORS' CONCLUSIONS Four trials have evaluated adding IRS using 'non-pyrethroid-like' insecticides in communities using ITNs. Some of these trials showed effects, and others did not. Three trials have evaluated adding IRS using 'pyrethroid-like' insecticides in communities using ITNs, and these studies did not detect an additional effect of the IRS. Given the wide geographical variety of malaria endemicities, transmission patterns, and insecticide resistance, we need to be cautious with inferences to policy from the limited number of trials conducted to date, and to develop relevant further research to inform decisions.
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Affiliation(s)
- Leslie Choi
- Liverpool School of Tropical MedicineDepartment of Clinical SciencesPembroke PlaceLiverpoolUKL3 5QA
| | - Joseph Pryce
- Liverpool School of Tropical MedicineDepartment of Clinical SciencesPembroke PlaceLiverpoolUKL3 5QA
| | - Paul Garner
- Liverpool School of Tropical MedicineDepartment of Clinical SciencesPembroke PlaceLiverpoolUKL3 5QA
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