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In vitro and in silico analysis of the Anopheles anticholinesterase activity of terpenoids. Parasitol Int 2023; 93:102713. [PMID: 36455706 DOI: 10.1016/j.parint.2022.102713] [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: 09/21/2022] [Revised: 11/22/2022] [Accepted: 11/23/2022] [Indexed: 11/29/2022]
Abstract
Anopheles gambiae, An. coluzzii, An. arabiensis, and An. funestus are major vectors in high malaria endemic African regions. Various terpenoid classes form the main chemical constituent repository of essential oils, many of which have been shown to possess insecticidal effects against Anopheles species. The current study aimed to assess the bioactivity of terpenoids including four sesquiterpene alcohols, farnesol, (-)-α-bisabolol, cis-nerolidol, and trans-nerolidol; a phenylpropanoid, methyleugenol, and a monoterpene, (R)-(+)-limonene, using the larvicidal screening assay against the four Anopheles species. The mechanism of action was investigated through in vitro acetylcholinesterase inhibition assay and in silico molecular modelling. All six terpenoids showed potent larvicidal activity against the four Anopheles species. Insights into the mechanism of action revealed that the six terpenoids are strong AChE inhibitors against An. funestus and An. arabiensis, while there was a moderate inhibitory activity against An. gambiae AChE, but very weak activity against An. coluzzii. Interestingly, in the in silico study, farnesol established a favourable hydrogen bonding interaction with a conserved amino acid residue, Cys447, at the entrance to the active site gorge. While (-)-α-bisabolol and methyleugenol displayed a strong interaction with the catalytic Ser360 and adjacent amino acid residues; but sparing the mutable Gly280 residue that confers resistance to the current anticholinesterase insecticides. As a result, this study identified farnesol, (-)-α-bisabolol, and methyleugenol as selective bioinsecticidal agents with potent Anopheles AChE inhibition. These terpenoids present as natural compounds for further development as anticholinesterase bioinsecticides.
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2
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Rants'o TA, Koekemoer LL, van Zyl RL. The insecticidal activity of essential oil constituents against pyrethroid-resistant Anopheles funestus (Diptera: Culicidae). Parasitol Int 2023; 95:102749. [PMID: 36898498 DOI: 10.1016/j.parint.2023.102749] [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: 02/02/2023] [Revised: 03/03/2023] [Accepted: 03/07/2023] [Indexed: 03/12/2023]
Abstract
Malaria vector control relies on the use of insecticides for indoor residual spraying and long-lasting bed nets. However, insecticide resistance to pyrethroids among others, has escalated. Anopheles funestus, one of the major African malaria vectors, has attained significant levels of resistance to pyrethroids. Overexpressed P450 monooxygenases have been previously identified in pyrethroid resistant An. funestus. The escalating resistance against conventional insecticides signals an urgent need for identification of novel insecticides. Essential oils have gained recognition as promising sources of alternative natural insecticides. This study investigated six essential oil constituents, farnesol, (-)-α-bisabolol, cis-nerolidol, trans-nerolidol, methyleugenol, santalol (α and β isomers) and essential oil of sandalwood, for the adulticidal effects against pyrethroid-resistant An. funestus strain. The susceptibility against these terpenoids were evaluated on both pyrethroid-susceptible and resistant An. funestus. Furthermore, the presence of overexpressed monooxygenases in resistant An. funestus was confirmed. Results showed that both the pyrethroid-susceptible and resistant An. funestus were susceptible to three EOCs; cis-nerolidol, trans-nerolidol and methyleugenol. On the other hand, the pyrethroid-resistant An. funestus survived exposure to both farnesol and (-)-α-bisabolol. This study however does not show any direct association of the overexpressed Anopheles monooxygenases and the efficacy of farnesol and (-)-α-bisabolol. The enhanced activity of these terpenoids against resistant An. funestus that has been pre-exposed to a synergist, piperonyl butoxide, suggests their potential effectiveness in combination with monooxygenase inhibitors. This study proposes that cis-nerolidol, trans-nerolidol and methyleugenol are potential agents for further investigation as novel bioinsecticides against pyrethroid-resistant An. funestus strain.
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Affiliation(s)
- Thankhoe A Rants'o
- Pharmacology Division, Department of Pharmacy and Pharmacology, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa; WITS Research Institute for Malaria, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa.
| | - Lizette L Koekemoer
- WITS Research Institute for Malaria, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa; School of Pathology, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa; Centre for Emerging Zoonotic and Parasitic Diseases, National Institute for Communicable Diseases of the National Health Laboratory Service, Johannesburg, South Africa
| | - Robyn L van Zyl
- Pharmacology Division, Department of Pharmacy and Pharmacology, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa; WITS Research Institute for Malaria, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa
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3
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Rants’o TA, van Greunen DG, van der Westhuizen CJ, Riley DL, Panayides JL, Koekemoer LL, van Zyl RL. The in silico and in vitro analysis of donepezil derivatives for Anopheles acetylcholinesterase inhibition. PLoS One 2022; 17:e0277363. [PMID: 36350894 PMCID: PMC9645637 DOI: 10.1371/journal.pone.0277363] [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: 07/10/2022] [Accepted: 10/25/2022] [Indexed: 11/11/2022] Open
Abstract
Current studies on Anopheles anticholinesterase insecticides are focusing on identifying agents with high selectivity towards Anopheles over mammalian targets. Acetylcholinesterase (AChE) from electric eel is often used as the bioequivalent enzyme to study ligands designed for activity and inhibition in human. In this study, previously identified derivatives of a potent AChE, donepezil, that have exhibited low activity on electric eel AChE were assessed for potential AChE-based larvicidal effects on four African malaria vectors; An. funestus, An. arabiensis, An. gambiae and An. coluzzii. This led to the identification of four larvicidal agents with a lead molecule, 1-benzyl-N-(thiazol-2-yl) piperidine-4-carboxamide 2 showing selectivity for An. arabiensis as a larvicidal AChE agent. Differential activities of this molecule on An. arabiensis and electric eel AChE targets were studied through molecular modelling. Homology modelling was used to generate a three-dimensional structure of the An. arabiensis AChE for this binding assay. The conformation of this molecule and corresponding interactions with the AChE catalytic site was markedly different between the two targets. Assessment of the differences between the AChE binding sites from electric eel, human and Anopheles revealed that the electric eel and human AChE proteins were very similar. In contrast, Anopheles AChE had a smaller cysteine residue in place of bulky phenylalanine group at the entrance to the catalytic site, and a smaller aspartic acid residue at the base of the active site gorge, in place of the bulky tyrosine residues. Results from this study suggest that this difference affects the ligand orientation and corresponding interactions at the catalytic site. The lead molecule 2 also formed more favourable interactions with An. arabiensis AChE model than other Anopheles AChE targets, possibly explaining the observed selectivity among other assessed Anopheles species. This study suggests that 1-benzyl-N-(thiazol-2-yl) piperidine-4-carboxamide 2 may be a lead compound for designing novel insecticides against Anopheles vectors with reduced toxic potential on humans.
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Affiliation(s)
- Thankhoe A. Rants’o
- Pharmacology Division, Department of Pharmacy and Pharmacology, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa
- WITS Research Institute for Malaria (WRIM), Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa
- * E-mail:
| | - Divan G. van Greunen
- Department of Chemistry, Natural and Agricultural Sciences, University of Pretoria, Tshwane, South Africa
| | - C. Johan van der Westhuizen
- Department of Chemistry, Natural and Agricultural Sciences, University of Pretoria, Tshwane, South Africa
- Pharmaceutical Technologies, CSIR Future Production: Chemicals, Tshwane, South Africa
| | - Darren L. Riley
- Department of Chemistry, Natural and Agricultural Sciences, University of Pretoria, Tshwane, South Africa
| | - Jenny-Lee Panayides
- Pharmaceutical Technologies, CSIR Future Production: Chemicals, Tshwane, South Africa
| | - Lizette L. Koekemoer
- WITS Research Institute for Malaria (WRIM), Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa
- School of Pathology, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa
- Centre for Emerging Zoonotic and Parasitic Diseases, National Institute for Communicable Diseases of the National Health Laboratory Service, Johannesburg, South Africa
| | - Robyn L. van Zyl
- Pharmacology Division, Department of Pharmacy and Pharmacology, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa
- WITS Research Institute for Malaria (WRIM), Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa
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4
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Expression of mosquito miRNAs in entomopathogenic fungus induces pathogen-mediated host RNA interference and increases fungal efficacy. Cell Rep 2022; 41:111527. [PMID: 36288711 DOI: 10.1016/j.celrep.2022.111527] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2022] [Revised: 08/18/2022] [Accepted: 09/28/2022] [Indexed: 11/21/2022] Open
Abstract
The growing threat of insecticide resistance prompts the urgent need to develop additional tools for mosquito control. Entomopathogenic fungi provide an eco-friendly alternative to chemical insecticides. One limitation to the use of mycoinsecticides is their relatively low virulence. Here, we report an approach for suppressing mosquito immunity and increasing fungal virulence. We engineered Beauveria bassiana to express Aedes immunosuppressive microRNAs (miRNAs) to induce host RNA interference (RNAi) immune responses. We show that engineered strains can produce and deliver the miRNAs into host cells to activate cross-kingdom RNAi during infection and suppress mosquito immunity by targeting multiple host genes, thereby dramatically increasing fungal virulence against Aedes aegypti and Galleria mellonella larvae. Importantly, expressing host miRNAs also significantly increases fungal virulence against insecticide-resistant mosquitoes, creating potential for insecticide-resistance management. This pathogen-mediated RNAi (pmRNAi)-based approach provides an innovative strategy to enhance the efficacy of fungal insecticides and eliminate the likelihood of resistance development.
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N'Do S, Bandibabone JB, Soma DD, Musaka BZ, Prudhomme J, Habamungu CC, Namountougou M, Sangaré I, Kientega M, Kaboré DAP, Bayili K, Yerbanga RS, Diabate A, Dabire RK, Ouedraogo JB, Belem AMG, Boëte C, Guardiola-Claramonte M, Chimanuka B. Insecticide resistance profiles in malaria vector populations from Sud-Kivu in the Democratic Republic of the Congo. Trans R Soc Trop Med Hyg 2021; 115:1339-1344. [PMID: 34324683 DOI: 10.1093/trstmh/trab116] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2021] [Revised: 07/02/2021] [Accepted: 07/14/2021] [Indexed: 11/13/2022] Open
Abstract
BACKGROUND Insecticide resistance has become a widespread problem causing a decline in the effectiveness of vector control tools in sub-Saharan Africa. In this situation, ongoing monitoring of vector susceptibility to insecticides is encouraged by the WHO to guide national malaria control programmes. Our study was conducted from April to November 2018 in Tchonka (Sud-Kivu, Democratic Republic of the Congo) and reported primary data on the resistance status of Anopheles funestus and Anopheles gambiae. METHODS Insecticide susceptibility bioassays were performed on wild populations of A. funestus and A. gambiae using WHO insecticide-impregnated papers at discriminating concentration. In addition, PCR was performed to identify mosquito species and to detect kdr and ace-1R mutations involved in insecticide resistance. RESULTS Bioassay results show resistance to all tested insecticides except pirimiphos-methyl, propoxur, fenitrothion and malathion with a mortality rate ranging from 95.48 to 99.86%. The addition of piperonyl butoxide (PBO) increased the susceptibility of vectors to deltamethrin and alpha-cypermethrin by exhibiting a mortality ranging from 91.50 to 95.86%. The kdr mutation was detected at high frequencies (approximately 0.98) within A. gambiae while ace-1R was not detected. CONCLUSIONS This study provides useful data on the insecticide resistance profiles of malaria vector populations to better manage vector control. Our results highlight that, despite the high level of resistance, organophosphorus compounds and pyrethroids + PBO remain effective against the vectors.
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Affiliation(s)
- Sévérin N'Do
- Médecins Sans Frontières (MSF) OCBA, Barcelona, Spain.,Institut de Recherche en Sciences de la Santé (IRSS), Bobo-Dioulasso, Burkina Faso.,Université Nazi Boni (UNB), Bobo-Dioulasso, Burkina Faso
| | - Janvier B Bandibabone
- Centre de Recherche en Sciences Naturelles de Lwiro (CRSN/Lwiro), Bukavu, Sud-Kivu, DRC
| | - Dieudonné D Soma
- Institut de Recherche en Sciences de la Santé (IRSS), Bobo-Dioulasso, Burkina Faso.,Université Nazi Boni (UNB), Bobo-Dioulasso, Burkina Faso
| | - Bertin Z Musaka
- Centre de Recherche en Sciences Naturelles de Lwiro (CRSN/Lwiro), Bukavu, Sud-Kivu, DRC
| | - Jorian Prudhomme
- Médecins Sans Frontières (MSF) OCBA, Barcelona, Spain.,Institut de Recherche pour le Développement (IRD), Marseille, France
| | - Claude C Habamungu
- Centre de Recherche en Sciences Naturelles de Lwiro (CRSN/Lwiro), Bukavu, Sud-Kivu, DRC
| | - Moussa Namountougou
- Institut de Recherche en Sciences de la Santé (IRSS), Bobo-Dioulasso, Burkina Faso.,Université Nazi Boni (UNB), Bobo-Dioulasso, Burkina Faso
| | - Ibrahim Sangaré
- Institut de Recherche en Sciences de la Santé (IRSS), Bobo-Dioulasso, Burkina Faso.,Université Nazi Boni (UNB), Bobo-Dioulasso, Burkina Faso
| | - Mahamadi Kientega
- Institut de Recherche en Sciences de la Santé (IRSS), Bobo-Dioulasso, Burkina Faso.,Université Nazi Boni (UNB), Bobo-Dioulasso, Burkina Faso
| | - Didier A P Kaboré
- Institut de Recherche en Sciences de la Santé (IRSS), Bobo-Dioulasso, Burkina Faso.,Université Nazi Boni (UNB), Bobo-Dioulasso, Burkina Faso
| | - Koama Bayili
- Institut de Recherche en Sciences de la Santé (IRSS), Bobo-Dioulasso, Burkina Faso
| | - R Serge Yerbanga
- Institut de Recherche en Sciences de la Santé (IRSS), Bobo-Dioulasso, Burkina Faso
| | - Abdoulaye Diabate
- Institut de Recherche en Sciences de la Santé (IRSS), Bobo-Dioulasso, Burkina Faso
| | - Roch K Dabire
- Institut de Recherche en Sciences de la Santé (IRSS), Bobo-Dioulasso, Burkina Faso
| | - Jean-Bosco Ouedraogo
- Institut de Recherche en Sciences de la Santé (IRSS), Bobo-Dioulasso, Burkina Faso
| | | | - Christophe Boëte
- Médecins Sans Frontières (MSF) OCBA, Barcelona, Spain.,ISEM, Université de Montpellier, CNRS, IRD, EPHE, Montpellier, France
| | | | - Bantuzeko Chimanuka
- Centre de Recherche en Sciences Naturelles de Lwiro (CRSN/Lwiro), Bukavu, Sud-Kivu, DRC.,Université Officielle de Bukavu (UOB), Bukavu, Sud-Kivu, DRC
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6
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Leshabane M, Dziwornu GA, Coertzen D, Reader J, Moyo P, van der Watt M, Chisanga K, Nsanzubuhoro C, Ferger R, Erlank E, Venter N, Koekemoer L, Chibale K, Birkholtz LM. Benzimidazole Derivatives Are Potent against Multiple Life Cycle Stages of Plasmodium falciparum Malaria Parasites. ACS Infect Dis 2021; 7:1945-1955. [PMID: 33673735 DOI: 10.1021/acsinfecdis.0c00910] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
The continued emergence of resistance to front-line antimalarial treatments is of great concern. Therefore, new compounds that potentially have a novel target in various developmental stages of Plasmodium parasites are needed to treat patients and halt the spread of malaria. Here, several benzimidazole derivatives were screened for activity against the symptom-causing intraerythrocytic asexual blood stages and the transmissible gametocyte stages of P. falciparum. Submicromolar activity was obtained for 54 compounds against asexual blood stage parasites with 6 potent at IC50 < 100 nM while not displaying any marked toxicity against mammalian cells. Nanomolar potency was also observed against gametocytes with two compounds active against early stage gametocytes and two compounds active against late-stage gametocytes. The transmission-blocking potential of the latter was confirmed as they could prevent male gamete exflagellation and the lead compound reduced transmission by 72% in an in vivo mosquito feeding model. These compounds therefore have activity against multiple stages of Plasmodium parasites with potential for differential targets.
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Affiliation(s)
- Meta Leshabane
- Department of Biochemistry, Genetics and Microbiology, Institute for Sustainable Malaria Control, University of Pretoria, Private Bag X20, Hatfield 0028, South Africa
| | | | - Dina Coertzen
- Department of Biochemistry, Genetics and Microbiology, Institute for Sustainable Malaria Control, University of Pretoria, Private Bag X20, Hatfield 0028, South Africa
| | - Janette Reader
- Department of Biochemistry, Genetics and Microbiology, Institute for Sustainable Malaria Control, University of Pretoria, Private Bag X20, Hatfield 0028, South Africa
| | - Phanankosi Moyo
- Department of Biochemistry, Genetics and Microbiology, Institute for Sustainable Malaria Control, University of Pretoria, Private Bag X20, Hatfield 0028, South Africa
| | - Mariëtte van der Watt
- Department of Biochemistry, Genetics and Microbiology, Institute for Sustainable Malaria Control, University of Pretoria, Private Bag X20, Hatfield 0028, South Africa
| | - Kelly Chisanga
- Department of Chemistry, University of Cape Town, Rondebosch 7701, South Africa
| | | | - Richard Ferger
- Department of Chemistry, University of Cape Town, Rondebosch 7701, South Africa
| | - Erica Erlank
- Wits Research Institute for Malaria, School of Pathology, Faculty of Health Sciences, University of the Witwatersrand, and Centre for Emerging Zoonotic and Parasitic Diseases, National Institute for Communicable Diseases of the National Health Laboratory Service, Johannesburg, 2193, South Africa
| | - Nelius Venter
- Wits Research Institute for Malaria, School of Pathology, Faculty of Health Sciences, University of the Witwatersrand, and Centre for Emerging Zoonotic and Parasitic Diseases, National Institute for Communicable Diseases of the National Health Laboratory Service, Johannesburg, 2193, South Africa
| | - Lizette Koekemoer
- Wits Research Institute for Malaria, School of Pathology, Faculty of Health Sciences, University of the Witwatersrand, and Centre for Emerging Zoonotic and Parasitic Diseases, National Institute for Communicable Diseases of the National Health Laboratory Service, Johannesburg, 2193, South Africa
| | - Kelly Chibale
- Department of Chemistry, University of Cape Town, Rondebosch 7701, South Africa
- Institute of Infectious Disease and Molecular Medicine, University of Cape Town, Rondebosch 7701, South Africa
- South African Medical Research Council Drug Discovery and Development Research Unit, University of Cape Town, Rondebosch 7701, South Africa
| | - Lyn-Marie Birkholtz
- Department of Biochemistry, Genetics and Microbiology, Institute for Sustainable Malaria Control, University of Pretoria, Private Bag X20, Hatfield 0028, South Africa
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7
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Loonen JACM, Dery DB, Musaka BZ, Bandibabone JB, Bousema T, van Lenthe M, Pop-Stefanija B, Fesselet JF, Koenraadt CJM. Identification of main malaria vectors and their insecticide resistance profile in internally displaced and indigenous communities in Eastern Democratic Republic of the Congo (DRC). Malar J 2020; 19:425. [PMID: 33228693 PMCID: PMC7684733 DOI: 10.1186/s12936-020-03497-x] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2020] [Accepted: 11/15/2020] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Malaria remains a major public health concern in the Democratic Republic of the Congo (DRC) and its control is affected by recurrent conflicts. Médecins Sans Frontières (MSF) initiated several studies to better understand the unprecedented incidence of malaria to effectively target and implement interventions in emergency settings. The current study evaluated the main vector species involved in malaria transmission and their resistance to insecticides, with the aim to propose the most effective tools and strategies for control of local malaria vectors. METHODS This study was performed in 52 households in Shamwana (Katanga, 2014), 168 households in Baraka (South Kivu, 2015) and 269 households in Kashuga (North Kivu, 2017). Anopheles vectors were collected and subjected to standardized Word Health Organization (WHO) and Center for Disease Control (CDC) insecticide susceptibility bioassays. Mosquito species determination was done using PCR and Plasmodium falciparum infection in mosquitoes was assessed by ELISA targeting circumsporozoite protein. RESULTS Of 3517 Anopheles spp. mosquitoes collected, Anopheles gambiae sensu lato (s.l.) (29.6%) and Anopheles funestus (69.1%) were the main malaria vectors. Plasmodium falciparum infection rates for An. gambiae s.l. were 1.0, 2.1 and 13.9% for Shamwana, Baraka and Kashuga, respectively. Anopheles funestus showed positivity rates of 1.6% in Shamwana and 4.4% in Baraka. No An. funestus were collected in Kashuga. Insecticide susceptibility tests showed resistance development towards pyrethroids in all locations. Exposure to bendiocarb, malathion and pirimiphos-methyl still resulted in high mosquito mortality. CONCLUSIONS This is one of only few studies from these conflict areas in DRC to report insecticide resistance in local malaria vectors. The data suggest that current malaria prevention methods in these populations are only partially effective, and require additional tools and strategies. Importantly, the results triggered MSF to consider the selection of a new insecticide for indoor residual spraying (IRS) and a new long-lasting insecticide-treated net (LLIN). The reinforcement of correct usage of LLINs and the introduction of targeted larviciding were also included as additional vector control tools as a result of the studies.
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Affiliation(s)
| | - Dominic B Dery
- Médecins Sans Frontières (MSF), Amsterdam, The Netherlands
| | - Bertin Z Musaka
- Département de Biologie, Centre de Recherche en Sciences Naturelles (CRSN/Lwiro), Bukavu, South Kivu, Democratic Republic of the Congo
| | - Janvier B Bandibabone
- Département de Biologie, Centre de Recherche en Sciences Naturelles (CRSN/Lwiro), Bukavu, South Kivu, Democratic Republic of the Congo
| | - Teun Bousema
- Department of Medical Microbiology, Radboud Institute for Health Sciences, Radboud University Medical Center, Nijmegen, The Netherlands
- Department of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London, UK
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8
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Marcombe S, Thammavong P, Luangamath P, Chonephetsarath S, Phommavanh N, Lakeomany K, Nilaxay S, Rahmani Z, Saverton PJ, Abdullateef OH, Forward J, Jacob AE, Khadam S, Ali W, Boer C, Kakinuma H, Hawkins J, Longstreeth R, Portwood NM, Smee M, Brown N, Kuyucu NC, Lechmere S, Stieger G, Maithaviphet S, Nambanya S, Brey PT, Jones AK. Malaria and Dengue Mosquito Vectors from Lao PDR Show a Lack of the rdl Mutant Allele Responsible for Cyclodiene Insecticide Resistance. JOURNAL OF MEDICAL ENTOMOLOGY 2020; 57:815-823. [PMID: 31807752 DOI: 10.1093/jme/tjz227] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/19/2019] [Indexed: 06/10/2023]
Abstract
The gamma-aminobutyric acid (GABA) receptor, RDL, plays important roles in neuronal signaling and is the target of highly effective insecticides. A mutation in RDL, commonly A296S, underlies resistance to several insecticides such as cyclodienes. Even though the use of cyclodienes has been banned, the occurrence of mutations substituting A296 is notably high in mosquitoes from several countries. Here, we report a survey investigating the prevalence of the Rdl mutant allele in mosquitoes from Laos, a country where mosquito-borne diseases such as malaria and dengue fever are health concerns. Anopheles and Aedes mosquitoes were collected from 12 provinces in Laos. Adult bioassays on Aedes aegypti (Linnaeus) (Diptera: Culicidae) and Aedes albopictus (Skuse) (Diptera: Culicidae) showed that all the populations tested were susceptible to dieldrin (4%) following WHO protocols. Exon 7 from a total of 791 mosquitoes was sequenced to identify the amino acid encoded for at 296 of RDL. Only one of these mosquitoes, Anopheles maculatus rampae Harbach and Somboon (Diptera: Culicidae) from Attapeu, carried the mutant allele being heterozygous for A296S. We therefore found a general lack of the Rdl mutant allele indicating that mosquitoes from Laos are not exposed to insecticides that act on the GABA receptor compared to mosquitoes in several other countries. Identifying the prevalence of the Rdl mutation may help inform the potential use of alternative insecticides that act on the GABA receptor should there be a need to replace pyrethroids in order to prevent/manage resistance.
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Affiliation(s)
- Sebastien Marcombe
- Institut Pasteur du Laos, Department of Entomology, Ministry of Health, Vientiane, Lao PDR
| | - Phoutmany Thammavong
- Institut Pasteur du Laos, Department of Entomology, Ministry of Health, Vientiane, Lao PDR
| | - Phonesavanh Luangamath
- Institut Pasteur du Laos, Department of Entomology, Ministry of Health, Vientiane, Lao PDR
| | | | - Nothasin Phommavanh
- Institut Pasteur du Laos, Department of Entomology, Ministry of Health, Vientiane, Lao PDR
| | - Khaitong Lakeomany
- Institut Pasteur du Laos, Department of Entomology, Ministry of Health, Vientiane, Lao PDR
| | - Somphat Nilaxay
- Institut Pasteur du Laos, Department of Entomology, Ministry of Health, Vientiane, Lao PDR
| | - Zuhal Rahmani
- Department of Biological and Medical Sciences, Oxford Brookes University, Headington, Oxford, UK
| | - Penelope J Saverton
- Department of Biological and Medical Sciences, Oxford Brookes University, Headington, Oxford, UK
| | - Omobolanle H Abdullateef
- Department of Biological and Medical Sciences, Oxford Brookes University, Headington, Oxford, UK
| | - Jordan Forward
- Department of Biological and Medical Sciences, Oxford Brookes University, Headington, Oxford, UK
| | - Anna E Jacob
- Department of Biological and Medical Sciences, Oxford Brookes University, Headington, Oxford, UK
| | - Safina Khadam
- Department of Biological and Medical Sciences, Oxford Brookes University, Headington, Oxford, UK
| | - Wlaa Ali
- Department of Biological and Medical Sciences, Oxford Brookes University, Headington, Oxford, UK
| | - Chloé Boer
- Department of Biological and Medical Sciences, Oxford Brookes University, Headington, Oxford, UK
| | - Hayato Kakinuma
- Department of Biological and Medical Sciences, Oxford Brookes University, Headington, Oxford, UK
| | - Joseph Hawkins
- Department of Biological and Medical Sciences, Oxford Brookes University, Headington, Oxford, UK
| | - Rosie Longstreeth
- Department of Biological and Medical Sciences, Oxford Brookes University, Headington, Oxford, UK
| | - Natalie M Portwood
- Department of Biological and Medical Sciences, Oxford Brookes University, Headington, Oxford, UK
| | - Madeleine Smee
- Department of Biological and Medical Sciences, Oxford Brookes University, Headington, Oxford, UK
| | - Natasha Brown
- Department of Biological and Medical Sciences, Oxford Brookes University, Headington, Oxford, UK
| | - Nursu C Kuyucu
- Department of Biological and Medical Sciences, Oxford Brookes University, Headington, Oxford, UK
| | - Susannah Lechmere
- Department of Biological and Medical Sciences, Oxford Brookes University, Headington, Oxford, UK
| | - Gabriela Stieger
- Department of Biological and Medical Sciences, Oxford Brookes University, Headington, Oxford, UK
| | - Santi Maithaviphet
- Center for Malariology, Parasitology and Entomology, Department of Entomology, Ministry of Health, Vientiane, Lao PDR
| | - Simone Nambanya
- Center for Malariology, Parasitology and Entomology, Department of Entomology, Ministry of Health, Vientiane, Lao PDR
| | - Paul T Brey
- Institut Pasteur du Laos, Department of Entomology, Ministry of Health, Vientiane, Lao PDR
| | - Andrew K Jones
- Department of Biological and Medical Sciences, Oxford Brookes University, Headington, Oxford, UK
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9
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Holmes CJ, Benoit JB. Biological Adaptations Associated with Dehydration in Mosquitoes. INSECTS 2019; 10:insects10110375. [PMID: 31661928 PMCID: PMC6920799 DOI: 10.3390/insects10110375] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/26/2019] [Revised: 10/22/2019] [Accepted: 10/23/2019] [Indexed: 12/05/2022]
Abstract
Diseases that are transmitted by mosquitoes are a tremendous health and socioeconomic burden with hundreds of millions of people being impacted by mosquito-borne illnesses annually. Many factors have been implicated and extensively studied in disease transmission dynamics, but knowledge regarding how dehydration impacts mosquito physiology, behavior, and resulting mosquito-borne disease transmission remain underdeveloped. The lapse in understanding on how mosquitoes respond to dehydration stress likely obscures our ability to effectively study mosquito physiology, behavior, and vectorial capabilities. The goal of this review is to develop a profile of factors underlying mosquito biology that are altered by dehydration and the implications that are related to disease transmission.
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Affiliation(s)
- Christopher J Holmes
- Department of Biological Sciences, University of Cincinnati, Cincinnati, OH 45221, USA.
| | - Joshua B Benoit
- Department of Biological Sciences, University of Cincinnati, Cincinnati, OH 45221, USA.
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10
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Mashatola T, Ndo C, Koekemoer LL, Dandalo LC, Wood OR, Malakoane L, Poumachu Y, Lobb LN, Kaiser M, Bourtzis K, Munhenga G. A review on the progress of sex-separation techniques for sterile insect technique applications against Anopheles arabiensis. Parasit Vectors 2018; 11:646. [PMID: 30583746 PMCID: PMC6304763 DOI: 10.1186/s13071-018-3219-4] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
The feasibility of the sterile insect technique (SIT) as a malaria vector control strategy against Anopheles arabiensis has been under investigation over the past decade. One of the critical steps required for the application of this technique to mosquito control is the availability of an efficient and effective sex-separation system. Sex-separation systems eliminate female mosquitoes from the production line prior to irradiation and field release of sterile males. This is necessary because female mosquitoes can transmit pathogens such as malaria and, therefore, their release must be prevented. Sex separation also increases the efficiency of an SIT programme. Various sex-separation strategies have been explored including the exploitation of developmental and behavioural differences between male and female mosquitoes, and genetic approaches. Most of these are however species-specific and are not indicated for the major African malaria vectors such as An. arabiensis. As there is currently no reliable sex-separation method for An. arabiensis, various strategies were explored in an attempt to develop a robust system that can be applied on a mass-rearing scale. The progress and challenges faced during the development of a sexing system for future pilot and/or large-scale SIT release programmes against An. arabiensis are reviewed here. Three methods of sex separation were examined. The first is the use of pupal size for gender prediction. The second is the elimination of blood-feeding adult females through the addition of an endectocide to a blood meal source. The third is the establishment of a genetic sexing strain (GSS) carrying an insecticide resistance selectable marker (dieldrin-resistance rdl gene and/or other GABA receptor antagonists that can be used as alternative insecticides to dieldrin) or a temperature-sensitive lethal marker.
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Affiliation(s)
- Thabo Mashatola
- Centre for Emerging Zoonotic and Parasitic Diseases, National Institute for Communicable Diseases of the National Health Laboratory Service, Johannesburg, South Africa
- Wits Research Institute for Malaria, MRC Collaborating Centre for Multi-Disciplinary Research on Malaria, School of Pathology, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa
- Insect Pest Control Laboratory, Joint FAO/IAEA Division of Nuclear Techniques in Food and Agriculture, Vienna, Austria
| | - Cyrille Ndo
- Organisation de Coordination pour la lutte Contre les Endémies en Afrique Centrale (OCEAC), Institut de recherche de Yaoundé (IRY), Yaoundé, Cameroon
- Department of Biological Sciences, Faculty of Medicine and Pharmaceutical Sciences, University of Douala, Douala, Cameroon
- Centre for Research in Infectious Disease (CRI), Yaoundé, Cameroon
| | - Lizette L. Koekemoer
- Centre for Emerging Zoonotic and Parasitic Diseases, National Institute for Communicable Diseases of the National Health Laboratory Service, Johannesburg, South Africa
- Wits Research Institute for Malaria, MRC Collaborating Centre for Multi-Disciplinary Research on Malaria, School of Pathology, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa
| | - Leonard C. Dandalo
- Centre for Emerging Zoonotic and Parasitic Diseases, National Institute for Communicable Diseases of the National Health Laboratory Service, Johannesburg, South Africa
- Wits Research Institute for Malaria, MRC Collaborating Centre for Multi-Disciplinary Research on Malaria, School of Pathology, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa
| | - Oliver R. Wood
- Centre for Emerging Zoonotic and Parasitic Diseases, National Institute for Communicable Diseases of the National Health Laboratory Service, Johannesburg, South Africa
- Wits Research Institute for Malaria, MRC Collaborating Centre for Multi-Disciplinary Research on Malaria, School of Pathology, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa
| | - Lerato Malakoane
- Centre for Emerging Zoonotic and Parasitic Diseases, National Institute for Communicable Diseases of the National Health Laboratory Service, Johannesburg, South Africa
- Wits Research Institute for Malaria, MRC Collaborating Centre for Multi-Disciplinary Research on Malaria, School of Pathology, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa
| | - Yacouba Poumachu
- Insect Pest Control Laboratory, Joint FAO/IAEA Division of Nuclear Techniques in Food and Agriculture, Vienna, Austria
- Organisation de Coordination pour la lutte Contre les Endémies en Afrique Centrale (OCEAC), Institut de recherche de Yaoundé (IRY), Yaoundé, Cameroon
- Vector Borne Disease Laboratory of the Applied Biology and Ecology Research Unit (VBDL-URBEA) Department of Animal Biology, Faculty of Sciences of the University of Dschang, Dschang, Cameroon
| | - Leanne N. Lobb
- Centre for Emerging Zoonotic and Parasitic Diseases, National Institute for Communicable Diseases of the National Health Laboratory Service, Johannesburg, South Africa
- Wits Research Institute for Malaria, MRC Collaborating Centre for Multi-Disciplinary Research on Malaria, School of Pathology, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa
| | - Maria Kaiser
- Centre for Emerging Zoonotic and Parasitic Diseases, National Institute for Communicable Diseases of the National Health Laboratory Service, Johannesburg, South Africa
- Wits Research Institute for Malaria, MRC Collaborating Centre for Multi-Disciplinary Research on Malaria, School of Pathology, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa
| | - Kostas Bourtzis
- Insect Pest Control Laboratory, Joint FAO/IAEA Division of Nuclear Techniques in Food and Agriculture, Vienna, Austria
| | - Givemore Munhenga
- Centre for Emerging Zoonotic and Parasitic Diseases, National Institute for Communicable Diseases of the National Health Laboratory Service, Johannesburg, South Africa
- Wits Research Institute for Malaria, MRC Collaborating Centre for Multi-Disciplinary Research on Malaria, School of Pathology, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa
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11
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Nardini L, Hunt RH, Dahan-Moss YL, Christie N, Christian RN, Coetzee M, Koekemoer LL. Malaria vectors in the Democratic Republic of the Congo: the mechanisms that confer insecticide resistance in Anopheles gambiae and Anopheles funestus. Malar J 2017; 16:448. [PMID: 29115954 PMCID: PMC5678590 DOI: 10.1186/s12936-017-2099-y] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2017] [Accepted: 10/28/2017] [Indexed: 11/22/2022] Open
Abstract
Background The Democratic Republic of the Congo (DRC) is characterized as a holoendemic malaria area with the main vectors being Anopheles funestus and members of the Anopheles gambiae complex. Due to political instability and socio-economic challenges in the region, knowledge of insecticide resistance status and resistance mechanisms in these vectors is limited. Mosquitoes were collected from a mining site in the north-eastern part of the country and, following identification, were subjected to extensive testing for the target-site and biochemical basis of resistance. Quantitative real-time PCR was used to assess a suite of 10 genes frequently involved in pyrethroid and dichlorodiphenyltrichloroethane (DDT) resistance in An. gambiae females and males. In An. funestus, gene expression microarray analysis was carried out on female mosquitoes. Results In both species, deltamethrin resistance was recorded along with high resistance and suspected resistance to DDT in An. gambiae and An. funestus, respectively. A total of 85% of An. gambiae carried the kdr mutations as either homozygous resistant (RR) (L1014S, L1014F or both) or heterozygous (RS), however only 3% carried the rdl mutant allele (RS) and no ace-1 mutations were recorded. Synergist assays indicated a strong role for P450s in deltamethrin resistance in both species. In An. gambiae, analysis of transcription levels showed that the glutathione-S-transferase, GSTS1-2, produced the highest fold change in expression (7.6-fold in females and 31-fold in males) followed by GSTE2, thioredoxin peroxidase (TPX2), and cytochrome oxidases (CYP6M2 and CYP6P1). All other genes tested produced fold change values below 2. Microarray analysis revealed significant over-transcription of cuticular proteins as well as CYP6M7, CYP6P9a and CYP6P9b in insecticide resistant An. funestus. Conclusions These data show that high levels of deltamethrin resistance in the main malaria vector species, conferred by enzymatic detoxification, are present in the DRC. Electronic supplementary material The online version of this article (10.1186/s12936-017-2099-y) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Luisa Nardini
- Wits Research Institute for Malaria, School of Pathology, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, 2000, South Africa.,Centre for Emerging, Zoonotic & Parasitic Diseases, National Institute for Communicable Diseases, Johannesburg, 2131, South Africa
| | - Richard H Hunt
- Wits Research Institute for Malaria, School of Pathology, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, 2000, South Africa.,Centre for Emerging, Zoonotic & Parasitic Diseases, National Institute for Communicable Diseases, Johannesburg, 2131, South Africa
| | - Yael L Dahan-Moss
- Wits Research Institute for Malaria, School of Pathology, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, 2000, South Africa.,Centre for Emerging, Zoonotic & Parasitic Diseases, National Institute for Communicable Diseases, Johannesburg, 2131, South Africa
| | - Nanette Christie
- Department of Genetics, Forestry and Agricultural Biotechnology Institute, University of Pretoria, Pretoria, 0028, South Africa
| | - Riann N Christian
- Wits Research Institute for Malaria, School of Pathology, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, 2000, South Africa.,Centre for Emerging, Zoonotic & Parasitic Diseases, National Institute for Communicable Diseases, Johannesburg, 2131, South Africa
| | - Maureen Coetzee
- Wits Research Institute for Malaria, School of Pathology, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, 2000, South Africa.,Centre for Emerging, Zoonotic & Parasitic Diseases, National Institute for Communicable Diseases, Johannesburg, 2131, South Africa
| | - Lizette L Koekemoer
- Wits Research Institute for Malaria, School of Pathology, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, 2000, South Africa. .,Centre for Emerging, Zoonotic & Parasitic Diseases, National Institute for Communicable Diseases, Johannesburg, 2131, South Africa.
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12
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Chand G, Behera P, Bang A, Singh N. Status of insecticide resistance in An. culicifacies in Gadchiroli (Maharashtra) India. Pathog Glob Health 2017; 111:362-366. [PMID: 28971738 DOI: 10.1080/20477724.2017.1378836] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022] Open
Abstract
An. culicifacies is the major vector of malaria in tribal community and tribal dominated areas in India. Development of resistance to insecticides is the major challenge to curb the transmission. Gadchiroli (Maharashtra) is a tribal district in central India where incidence of malaria increased from 2012 to 2015 despite indoor space spray with synthetic pyrethroids. To determine the susceptibility status of An. culicifacies against commonly used insecticides in public health program in Gadchiroli. standard WHO method and test kit were used. The insecticide impregnated papers were procured from vector control unit Malaysia. An. culicifacies found resistance to three major groups of pesticides i.e. organochlorine (DDT 4%), organophosphorous (Malathion 5%) and pyrethroids (Cyfluthrin 0.15%, Deltametherin 0.05% and Lambdacyhalothrin 0.05%). The susceptibility status in Permethrin 0.75% needs further confirmation. Development of resistance to different insecticides of varied groups is an adverse finding for the elimination of malaria, explaining the recent increase in malaria incidence in Gadchiroli. The phenomenon further needs to be studied in different locations and the susceptibility needs to test against other insecticides. The findings may have significant implications to the choice of insecticides in the malaria control program in tribal areas.
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Affiliation(s)
- Gyan Chand
- a National Institute for Research in Tribal Health , Jabalpur , India
| | - Priyamadhaba Behera
- b Society for Education, Action and Research in Community Health , Gadchiroli , India
| | - Abhay Bang
- b Society for Education, Action and Research in Community Health , Gadchiroli , India
| | - Neeru Singh
- a National Institute for Research in Tribal Health , Jabalpur , India
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13
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Olé Sangba ML, Sidick A, Govoetchan R, Dide-Agossou C, Ossè RA, Akogbeto M, Ndiath MO. Evidence of multiple insecticide resistance mechanisms in Anopheles gambiae populations in Bangui, Central African Republic. Parasit Vectors 2017; 10:23. [PMID: 28086840 PMCID: PMC5237250 DOI: 10.1186/s13071-016-1965-8] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2016] [Accepted: 12/31/2016] [Indexed: 11/30/2022] Open
Abstract
Background Knowledge of insecticide resistance status in the main malaria vectors is an essential component of effective malaria vector control. This study presents the first evaluation of the status of insecticide resistance in Anopheles gambiae populations from Bangui, the Central African Republic. Methods Anopheles mosquitoes were reared from larvae collected in seven districts of Bangui between September to November 2014. The World Health Organisation’s bioassay susceptibility tests to lambda-cyhalothrin (0.05%), deltamethrin (0.05%), DDT (4%), malathion (5%), fenitrothion (1%) and bendiocarb (0.1%) were performed on adult females. Species and molecular forms as well as the presence of L1014F kdr and Ace-1R mutations were assessed by PCR. Additional tests were conducted to assess metabolic resistance status. Results After 1 h exposure, a significant difference of knockdown effect was observed between districts in all insecticides tested except deltamethrin and malathion. The mortality rate (MR) of pyrethroids group ranging from 27% (CI: 19–37.5) in Petevo to 86% (CI: 77.6–92.1) in Gbanikola; while for DDT, MR ranged from 5% (CI: 1.6–11.3) in Centre-ville to 39% (CI: 29.4–49.3) in Ouango. For the organophosphate group a MR of 100% was observed in all districts except Gbanikola where a MR of 96% (CI: 90–98.9) was recorded. The mortality induced by bendiocarb was very heterogeneous, ranging from 75% (CI: 62.8–82.8) in Yapele to 99% (CI: 84.5–100) in Centre-ville. A high level of kdr-w (L1014F) frequency was observed in all districts ranging from 93 to 100%; however, no kdr-e (L1014S) and Ace-1R mutation were found in all tested mosquitoes. Data of biochemical analysis showed significant overexpression activities of cytochrome P450, GST and esterases in Gbanikola and Yapele (χ2 = 31.85, df = 2, P < 0.001). By contrast, esterases activities using α and β-naphthyl acetate were significantly low in mosquitoes from PK10 and Ouango in comparison to Kisumu strain (χ2 = 17.34, df = 2, P < 0.005). Conclusions Evidence of resistance to DDT and pyrethroids as well as precocious emergence of resistance to carbamates were detected among A. gambiae mosquitoes from Bangui, including target-site mutations and metabolic mechanisms. The co-existence of these resistance mechanisms in A. gambiae may be a serious obstacle for the future success of malaria control programmes in this region. Electronic supplementary material The online version of this article (doi:10.1186/s13071-016-1965-8) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Marina Lidwine Olé Sangba
- G4 Malaria Group, Institut Pasteur of Bangui, BP 926, Bangui, Central African Republic.,Faculté des Sciences et Techniques, Université d'Abomey Calavi, Cotonou, Benin.,Centre de Recherche Entomologique de Cotonou (CREC), Cotonou, 06 BP 2604, Benin
| | - Aboubakar Sidick
- Centre de Recherche Entomologique de Cotonou (CREC), Cotonou, 06 BP 2604, Benin
| | - Renaud Govoetchan
- Centre de Recherche Entomologique de Cotonou (CREC), Cotonou, 06 BP 2604, Benin.,Ecole Nationale des Sciences et Techniques Agricole de Djougou (ENSTA), Université des Sciences Arts et Techniques de Natitingou (USATN), Natitingou, Benin
| | - Christian Dide-Agossou
- University of Colorado Denver Anschutz Medical Campus, 13001 E 17th Pl, Aurora, CO, 80045, USA
| | - Razaki A Ossè
- Centre de Recherche Entomologique de Cotonou (CREC), Cotonou, 06 BP 2604, Benin.,Ecole de Gestion et d'Exploitation des Systèmes d'Elevage (EGESE), Université d'Agriculture de Kétou (UAK), Kétou, Benin
| | - Martin Akogbeto
- Faculté des Sciences et Techniques, Université d'Abomey Calavi, Cotonou, Benin.,Centre de Recherche Entomologique de Cotonou (CREC), Cotonou, 06 BP 2604, Benin
| | - Mamadou Ousmane Ndiath
- G4 Malaria Group, Institut Pasteur of Bangui, BP 926, Bangui, Central African Republic. .,G4 Malaria Group, Institut Pasteur of Madagascar BP 1274, Ambatofotsikely Avaradoha 101, Antananarivo, Madagascar.
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14
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Koukouikila-Koussounda F, Ntoumi F. Malaria epidemiological research in the Republic of Congo. Malar J 2016; 15:598. [PMID: 28010728 PMCID: PMC5180396 DOI: 10.1186/s12936-016-1617-7] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2016] [Accepted: 11/15/2016] [Indexed: 12/13/2022] Open
Abstract
BACKGROUND Reliable and comprehensive information on the burden of malaria is critical for guiding national and international efforts in malaria control. The purpose of this review is to provide an overview of published data and available information on malaria resulting from field studies/investigations conducted in the Republic of Congo (RoC) from 1992 to 2015, as baseline for assisting public health authorities and researchers to define future research priorities as well as interventions. METHODS This review considers data from peer-reviewed articles and information from the National Malaria Control Programme reports, based on field investigations or samples collected from 1992 to 2015. Peer-reviewed papers were searched throughout online bibliographic databases PubMed, HINARI and Google Scholar using the following terms: "malaria", "Congo", "Brazzaville", "prevalence", "antimalarial", "efficacy", "falciparum", "genetic", "diversity". Original articles and reviews were included and selection of relevant papers was made. RESULTS Twenty-eight published articles were included in this review and two additional records from the National Malaria Control Programme were also considered. The majority of studies were conducted in Brazzaville and Pointe-Noire. CONCLUSION The present systematic review reveals that number of studies have been conducted in the RoC with regard to malaria. However, their results cannot formally be generalized at the country level. This suggests a need for implementing regular multisite investigations and surveys that may be representative of the country, calling for the support and lead of the Ministry of Health.
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Affiliation(s)
| | - Francine Ntoumi
- Fondation Congolaise Pour la Recherche Médicale, Villa D6, WHO AFRO Campus, Brazzaville, Republic of Congo. .,Faculty of Sciences and Techniques, University Marien Ngouabi, Brazzaville, Republic of Congo. .,Institute for Tropical Medicine, University of Tübingen, Tübingen, Germany.
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15
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Donnelly MJ, Isaacs AT, Weetman D. Identification, Validation, and Application of Molecular Diagnostics for Insecticide Resistance in Malaria Vectors. Trends Parasitol 2015; 32:197-206. [PMID: 26750864 DOI: 10.1016/j.pt.2015.12.001] [Citation(s) in RCA: 71] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2015] [Revised: 11/27/2015] [Accepted: 12/02/2015] [Indexed: 12/20/2022]
Abstract
Insecticide resistance is a major obstacle to control of Anopheles malaria mosquitoes in sub-Saharan Africa and requires an improved understanding of the underlying mechanisms. Efforts to discover resistance genes and DNA markers have been dominated by candidate gene and quantitative trait locus studies of laboratory strains, but with greater availability of genome sequences a shift toward field-based agnostic discovery is anticipated. Mechanisms evolve continually to produce elevated resistance yielding multiplicative diagnostic markers, co-screening of which can give high predictive value. With a shift toward prospective analyses, identification and screening of resistance marker panels will boost monitoring and programmatic decision making.
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Affiliation(s)
- Martin J Donnelly
- Department of Vector Biology, Liverpool School of Tropical Medicine, Pembroke Place, Liverpool L3 5QA, UK; Malaria Programme, Wellcome Trust Sanger Institute, Cambridge, UK.
| | - Alison T Isaacs
- Department of Vector Biology, Liverpool School of Tropical Medicine, Pembroke Place, Liverpool L3 5QA, UK
| | - David Weetman
- Department of Vector Biology, Liverpool School of Tropical Medicine, Pembroke Place, Liverpool L3 5QA, UK
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16
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Okorie PN, Ademowo GO, Irving H, Kelly-Hope LA, Wondji CS. Insecticide susceptibility of Anopheles coluzzii and Anopheles gambiae mosquitoes in Ibadan, Southwest Nigeria. MEDICAL AND VETERINARY ENTOMOLOGY 2015; 29:44-50. [PMID: 25417803 PMCID: PMC4319996 DOI: 10.1111/mve.12089] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/19/2014] [Revised: 08/26/2014] [Accepted: 09/03/2014] [Indexed: 06/04/2023]
Abstract
The emergence of insecticide resistance in Anopheles (Diptera: Culicidae) mosquitoes has great implications for malaria control in Nigeria. This study aimed to determine the dynamics of insecticide susceptibility levels and the frequency of knock-down resistance (kdr) mutations (L1014F) in wild Anopheles coluzzii Coetzee & Wilkerson sp. n. and Anopheles gambiae Giles from the Ojoo and Bodija areas of Ibadan, in southwest Nigeria. Insecticide susceptibility to pyrethroids, organophosphates, carbamates and organochlorines was assessed using World Health Organization (WHO) bioassays. A subset of the mosquitoes exposed to pyrethroids and DDT was used for species and molecular form identification; kdr genotyping was determined using the TaqMan real-time polymerase chain reaction assay. The mosquitoes were resistant to pyrethroids and DDT but completely susceptible to organophosphates and carbamates. Bodija samples (n = 186) consisted of An. gambiae (91.4%) and An. coluzzii (8.1%) and included one An. coluzzii/An. gambiae hybrid specimen. All mosquitoes screened in Ojoo (n = 26) were An. gambiae. The 1014F kdr mutation was detected at frequencies of 24.5 and 5.8% in Bodija and Ojoo, respectively. No correlation was observed between kdr genotypes and resistance phenotypes. The results indicate that metabolic resistance probably plays an important role in the development of resistance and highlight the need to implement insecticide resistance management strategies.
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Affiliation(s)
- Patricia N. Okorie
- Institute for Advanced Medical Research and Training, College of Medicine, University of Ibadan, Ibadan, Nigeria
| | - George O. Ademowo
- Institute for Advanced Medical Research and Training, College of Medicine, University of Ibadan, Ibadan, Nigeria
| | - Helen Irving
- Centre for Neglected Tropical Diseases and Vector Group – Liverpool School of Tropical Medicine, Liverpool, UK
| | - Louise A. Kelly-Hope
- Centre for Neglected Tropical Diseases and Vector Group – Liverpool School of Tropical Medicine, Liverpool, UK
| | - Charles S. Wondji
- Centre for Neglected Tropical Diseases and Vector Group – Liverpool School of Tropical Medicine, Liverpool, UK
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17
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Silva APB, Santos JMM, Martins AJ. Mutations in the voltage-gated sodium channel gene of anophelines and their association with resistance to pyrethroids - a review. Parasit Vectors 2014; 7:450. [PMID: 25292318 PMCID: PMC4283120 DOI: 10.1186/1756-3305-7-450] [Citation(s) in RCA: 93] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2014] [Accepted: 09/01/2014] [Indexed: 12/14/2022] Open
Abstract
Constant and extensive use of chemical insecticides has created a selection pressure and favored resistance development in many insect species worldwide. One of the most important pyrethroid resistance mechanisms is classified as target site insensitivity, due to conformational changes in the target site that impair a proper binding of the insecticide molecule. The voltage-gated sodium channel (NaV) is the target of pyrethroids and DDT insecticides, used to control insects of medical, agricultural and veterinary importance, such as anophelines. It has been reported that the presence of a few non-silent point mutations in the NaV gene are associated with pyrethroid resistance, termed as 'kdr' (knockdown resistance) for preventing the knockdown effect of these insecticides. The presence of these mutations, as well as their effects, has been thoroughly studied in Anopheles mosquitoes. So far, kdr mutations have already been detected in at least 13 species (Anopheles gambiae, Anopheles arabiensis, Anopheles sinensis, Anopheles stephensi, Anopheles subpictus, Anopheles sacharovi, Anopheles culicifacies, Anopheles sundaicus, Anopheles aconitus, Anopheles vagus, Anopheles paraliae, Anopheles peditaeniatus and Anopheles albimanus) from populations of African, Asian and, more recently, American continents. Seven mutational variants (L1014F, L1014S, L1014C, L1014W, N1013S, N1575Y and V1010L) were described, with the highest prevalence of L1014F, which occurs at the 1014 site in NaV IIS6 domain. The increase of frequency and distribution of kdr mutations clearly shows the importance of this mechanism in the process of pyrethroid resistance. In this sense, several species-specific and highly sensitive methods have been designed in order to genotype individual mosquitoes for kdr in large scale, which may serve as important tolls for monitoring the dynamics of pyrethroid resistance in natural populations. We also briefly discuss investigations concerning the course of Plasmodium infection in kdr individuals. Considering the limitation of insecticides available for employment in public health campaigns and the absence of a vaccine able to brake the life cycle of the malaria parasites, the use of pyrethroids is likely to remain as the main strategy against mosquitoes by either indoor residual spraying (IR) and insecticide treated nets (ITN). Therefore, monitoring insecticide resistance programs is a crucial need in malaria endemic countries.
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Affiliation(s)
- Ana Paula B Silva
- />Laboratório de Malária e Dengue, Instituto Nacional de Pesquisas da Amazônia, Av. André Araújo, 2936, Petrópolis, CEP 69067-375 Manaus, Amazonas Brazil
| | - Joselita Maria M Santos
- />Laboratório de Malária e Dengue, Instituto Nacional de Pesquisas da Amazônia, Av. André Araújo, 2936, Petrópolis, CEP 69067-375 Manaus, Amazonas Brazil
| | - Ademir J Martins
- />Laboratório de Fisiologia e Controle de Artrópodes Vetores, Instituto Oswaldo Cruz, FIOCRUZ, Rio de Janeiro, Brazil
- />Instituto Nacional de Ciência e Tecnologia em Entomologia Molecular, Rio de Janeiro, Brazil
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Haji KA, Khatib BO, Smith S, Ali AS, Devine GJ, Coetzee M, Majambere S. Challenges for malaria elimination in Zanzibar: pyrethroid resistance in malaria vectors and poor performance of long-lasting insecticide nets. Parasit Vectors 2013; 6:82. [PMID: 23537463 PMCID: PMC3639098 DOI: 10.1186/1756-3305-6-82] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2013] [Accepted: 03/22/2013] [Indexed: 11/30/2022] Open
Abstract
Background Long-lasting insecticide treated nets (LLINs) and indoor residual house spraying (IRS) are the main interventions for the control of malaria vectors in Zanzibar. The aim of the present study was to assess the susceptibility status of malaria vectors against the insecticides used for LLINs and IRS and to determine the durability and efficacy of LLINs on the island. Methods Mosquitoes were sampled from Pemba and Unguja islands in 2010–2011 for use in WHO susceptibility tests. One hundred and fifty LLINs were collected from households on Unguja, their physical state was recorded and then tested for efficacy as well as total insecticide content. Results Species identification revealed that over 90% of the Anopheles gambiae complex was An. arabiensis with a small number of An. gambiae s.s. and An. merus being present. Susceptibility tests showed that An. arabiensis on Pemba was resistant to the pyrethroids used for LLINs and IRS. Mosquitoes from Unguja Island, however, were fully susceptible to all pyrethroids tested. A physical examination of 150 LLINs showed that two thirds were damaged after only three years in use. All used nets had a significantly lower (p < 0.001) mean permethrin concentration of 791.6 mg/m2 compared with 944.2 mg/m2 for new ones. Their efficacy decreased significantly against both susceptible An. gambiae s.s. colony mosquitoes and wild-type mosquitoes from Pemba after just six washes (p < 0.001). Conclusion The sustainability of the gains achieved in malaria control in Zanzibar is seriously threatened by the resistance of malaria vectors to pyrethroids and the short-lived efficacy of LLINs. This study has revealed that even in relatively well-resourced and logistically manageable places like Zanzibar, malaria elimination is going to be difficult to achieve with the current control measures.
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Kamareddine L, Fan Y, Osta MA, Keyhani NO. Expression of trypsin modulating oostatic factor (TMOF) in an entomopathogenic fungus increases its virulence towards Anopheles gambiae and reduces fecundity in the target mosquito. Parasit Vectors 2013; 6:22. [PMID: 23336669 PMCID: PMC3571938 DOI: 10.1186/1756-3305-6-22] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2012] [Accepted: 01/14/2013] [Indexed: 12/03/2022] Open
Abstract
Background Adult and larval mosquitoes regulate food digestion in their gut with trypsin modulating oostatic factor (TMOF), a decapeptide hormone synthesized by the ovaries and the neuroendocrine system. TMOF is currently being developed as a mosquitocide, however, delivery of the peptide to the mosquito remains a significant challenge. Entomopathogenic fungi offer a means for targeting mosquitoes with TMOF. Findings The efficacy of wild type and transgenic Beauveria bassiana strains expressing Aedes aegypti TMOF (Bb-Aa1) were evaluated against larvae and sugar- and blood-fed adult Anopheles gambiae mosquitoes using insect bioassays. Bb-Aa1 displayed increased virulence against larvae, and sugar and blood fed adult A. gambiae when compared to the wild type parent strain. Median lethal dose (LD50) values decreased by ~20% for larvae, and ~40% for both sugar and blood-fed mosquitoes using Bb-Aa1 relative to the wild type parent. Median lethal time (LT50) values were lower for blood-fed compared to sugar-fed mosquitoes in infections with both wild type and Bb-Aa1. However, infection using Bb-Aa1 resulted in 15% to 25% reduction in LT50 values for sugar- and blood fed mosquitoes, and ~27% for larvae, respectively, relative to the wild type parent. In addition, infection with Bb-Aa1 resulted in a dramatic reduction in fecundity of the target mosquitoes. Conclusions B. bassiana expressing Ae. aegypti TMOF exhibited increased virulence against A. gambiae compared to the wild type strain. These data expand the range and utility of entomopathogenic fungi expressing mosquito-specific molecules to improve their biological control activities against mosquito vectors of disease.
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Affiliation(s)
- Layla Kamareddine
- Department of Biology, American University of Beirut, Bliss Street, Beirut, 11072020, Lebanon
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Basilua Kanza JP, El Fahime E, Alaoui S, Essassi EM, Brooke B, Nkebolo Malafu A, Watsenga Tezzo F. Pyrethroid, DDT and malathion resistance in the malaria vector Anopheles gambiae from the Democratic Republic of Congo. Trans R Soc Trop Med Hyg 2012; 107:8-14. [PMID: 23222943 DOI: 10.1093/trstmh/trs002] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
BACKGROUND Malaria remains the most important parasitic disease in sub-Saharan Africa. We investigated the extent of resistance in the malaria vector Anopheles gambiae from the Democratic Republic of Congo (DRC) to three classes of insecticide approved by WHO for indoor residual spraying. METHOD Standard WHO bioassays were performed on adult Anopheles mosquitoes reared in the laboratory from larvae collected from different sites. Molecular techniques were used for species identification and to identify knockdown resistance (kdr) and acetylcholinesterase (ace-1(R)) mutations in individual mosquitoes. RESULTS Only A. gambiae s.s., the nominal member of the A. gambiae species complex, was found. Bioassays showed phenotypic resistance to the main insecticides used in the region, notably pyrethroids (deltamethrin, permethrin, lambda-cyhalothrin), an organochlorine (DDT) and an organophosphate (malathion). The L1014F kdr allele, often associated with resistance to pyrethroids and DDT, was detected in samples from all collection sites at varying frequencies. No ace-1(R) resistance alleles (associated with organophosphate and carbamate resistance) were detected. CONCLUSIONS These data can be used to inform a resistance management strategy that requires comprehensive information concerning malaria vector species composition in the areas of interest, and their susceptibility to the insecticides proposed for their control.
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Affiliation(s)
- Jean Pierre Basilua Kanza
- Institut Supérieur des Techniques Médicales de Kinshasa (ISTM/KIN), Laboratoire Spécial d'Analyses Biomédicales, BP774 Kinshasa XI, Democratic Republic of Congo.
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Osta MA, Rizk ZJ, Labbé P, Weill M, Knio K. Insecticide resistance to organophosphates in Culex pipiens complex from Lebanon. Parasit Vectors 2012; 5:132. [PMID: 22759898 PMCID: PMC3414835 DOI: 10.1186/1756-3305-5-132] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2012] [Accepted: 07/03/2012] [Indexed: 11/25/2022] Open
Abstract
Background Analysis of Culex pipiens mosquitoes collected from a single site in Lebanon in 2005, revealed an alarming frequency of ace-1 alleles conferring resistance to organophosphate insecticides. Following this, in 2006 the majority of municipalities switched to pyrethroids after a long history of organophosphate usage in the country; however, since then no studies have assessed the impact of changing insecticide class on the frequency of resistant ace-1 alleles in C. pipiens. Methods C. pipiens mosquitoes were captured indoors from 25 villages across the country and subjected to established methods for the analysis of gene amplification at the Ester locus and target site mutations in ace-1 gene that confer resistance to organophosphates. Results We conducted the first large-scale screen for resistance to organosphosphates in C. pipiens mosquitoes collected from Lebanon. The frequency of carboxylesterase (Ester) and ace-1 alleles conferring resistance to organophosphates were assessed among C. pipiens mosquitoes collected from 25 different villages across the country between December 2008 and December 2009. Established enzymatic assay and PCR-based molecular tests, both diagnostic of the major target site mutations in ace-1 revealed the absence of the F290V mutation among sampled mosquitoes and significant reduction in the frequency of G119S mutation compared to that previously reported for mosquitoes collected from Beirut in 2005. We also identified a new duplicated ace-1 allele, named ace-1D13, exhibiting a resistant phenotype by associating a susceptible and a resistant copy of ace-1 in a mosquito line sampled from Beirut in 2005. Fisher’s exact test on ace-1 frequencies in the new sample sites, showed that some populations exhibited a significant excess of heterozygotes, suggesting that the duplicated allele is still present. Starch gel electrophoresis indicated that resistance at the Ester locus was mainly attributed to the Ester2 allele, which exhibits a broad geographical distribution. Conclusions Our analysis suggests that the frequency of resistant ace-1 alleles in mosquito populations can be downshifted, and in certain cases (F290V mutation) even eliminated, by switching to a different class of insecticides, possibly because of the fitness cost associated with these alleles.
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Affiliation(s)
- Mike A Osta
- Department of Biology, American University of Beirut, Bliss Street, Beirut, 11072020, Lebanon.
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Oduola AO, Idowu ET, Oyebola MK, Adeogun AO, Olojede JB, Otubanjo OA, Awolola TS. Evidence of carbamate resistance in urban populations of Anopheles gambiae s.s. mosquitoes resistant to DDT and deltamethrin insecticides in Lagos, South-Western Nigeria. Parasit Vectors 2012; 5:116. [PMID: 22686575 PMCID: PMC3409038 DOI: 10.1186/1756-3305-5-116] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2012] [Accepted: 06/11/2012] [Indexed: 11/10/2022] Open
Abstract
Background Resistance monitoring is essential in ensuring the success of insecticide based vector control programmes. This study was carried out to assess the susceptibility status of urban populations of Anopheles gambiae to carbamate insecticide being considered for vector control in mosquito populations previously reported to be resistant to DDT and permethrin. Methods Two – three day old adult female Anopheles mosquitoes reared from larval collections in 11 study sites from Local Government Areas of Lagos were exposed to test papers impregnated with DDT 4%, deltamethrin 0.05% and propoxur 0.1% insecticides. Additional tests were carried out to determine the susceptibility status of the Anopheles gambiae population to bendiocarb insecticide. Members of the A. gambiae complex, the molecular forms, were identified by PCR assays. The involvement of metabolic enzymes in carbamate resistance was assessed using Piperonyl butoxide (PBO) synergist assays. The presence of kdr-w/e and ace-1R point mutations responsible for DDT-pyrethroid and carbamate resistance mechanisms was also investigated by PCR. Results Propoxur resistance was found in 10 out of the 11 study sites. Resistance to three classes of insecticides was observed in five urban localities. Mortality rates in mosquitoes exposed to deltamethrin and propoxur did not show any significant difference (P > 0.05) but was significantly higher (P < 0.05) in populations exposed to DDT. All mosquitoes tested were identified as A. gambiae s.s (M form). The kdr -w point mutation at allelic frequencies between 45%-77% was identified as one of the resistant mechanisms responsible for DDT and pyrethroid resistance. Ace-1R point mutation was absent in the carbamate resistant population. However, the possible involvement of metabolic resistance was confirmed by synergistic assays conducted. Conclusion Evidence of carbamate resistance in A. gambiae populations already harbouring resistance to DDT and permethrin is a clear indication that calls for the implementation of insecticide resistance management strategies to combat the multiple resistance identified.
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Affiliation(s)
- Adedayo O Oduola
- Molecular Entomology and Vector Control Research Laboratory, Public Health Division, Nigerian Institute of Medical Research, Akoka, Lagos, Nigeria.
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Ndiath MO, Sougoufara S, Gaye A, Mazenot C, Konate L, Faye O, Sokhna C, Trape JF. Resistance to DDT and pyrethroids and increased kdr mutation frequency in An. gambiae after the implementation of permethrin-treated nets in Senegal. PLoS One 2012; 7:e31943. [PMID: 22384107 PMCID: PMC3285187 DOI: 10.1371/journal.pone.0031943] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2011] [Accepted: 01/20/2012] [Indexed: 11/19/2022] Open
Abstract
Introduction The aim of this study was to evaluate the susceptibility to insecticides of An. gambiae mosquitoes sampled in Dielmo (Senegal), in 2010, 2 years after the implementation of Long Lasting Insecticide-treated Nets (LLINs) and to report the evolution of kdr mutation frequency from 2006 to 2010. Methods WHO bioassay susceptibility tests to 6 insecticides were performed on adults F0, issuing from immature stages of An. gambiae s.l., sampled in August 2010. Species and molecular forms as well as the presence of L1014F and L1014S kdr mutations were assessed by PCR. Longitudinal study of kdr mutations was performed on adult mosquitoes sampled monthly by night landing catches from 2006 to 2010. Findings No specimen studied presented the L1014S mutation. During the longitudinal study, L1014F allelic frequency rose from 2.4% in year before the implementation of LLINs to 4.6% 0–12 months after and 18.7% 13–30 months after. In 2010, An. gambiae were resistant to DDT, Lambda-cyhalothrin, Deltamethrin and Permethrin (mortality rates ranging from 46 to 63%) but highly susceptible to Fenitrothion and Bendiocarb (100% mortality). There was significantly more RR genotype among An. gambiae surviving exposure to DDT or Pyrethroids. An. arabiensis represented 3.7% of the sampled mosquitoes (11/300) with no kdr resistance allele detected. An. gambiae molecular form M represented 29.7% of the mosquitoes with, among them, kdr genotypes SR (18%) and SS (82%). An. gambiae molecular form S represented 66% of the population with, among them, kdr genotype SS (33.3%), SR (55.6%) and RR (11.1%). Only 2 MS hybrid mosquitoes were sampled and presented SS kdr genotype. Conclusion Biological evidence of resistance to DDT and pyrethroids was detected among An. gambiae mosquitoes in Dielmo (Senegal) within 24 months of community use of LLINs. Molecular identification of L1014F mutation indicated that target site resistance increased after the implementation of LLINs.
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Affiliation(s)
- Mamadou O. Ndiath
- Institut de Recherche pour le Développement, Unité de Recherche sur les Maladies Infectieuses et Tropicales Emergentes (URMITE) UMR 198, Campus commun UCAD-IRD de Hann, BP 1386, CP 18524, Dakar, Sénégal
| | - Seynabou Sougoufara
- Institut de Recherche pour le Développement, Unité de Recherche sur les Maladies Infectieuses et Tropicales Emergentes (URMITE) UMR 198, Campus commun UCAD-IRD de Hann, BP 1386, CP 18524, Dakar, Sénégal
| | - Abdoulaye Gaye
- Institut de Recherche pour le Développement, Unité de Recherche sur les Maladies Infectieuses et Tropicales Emergentes (URMITE) UMR 198, Campus commun UCAD-IRD de Hann, BP 1386, CP 18524, Dakar, Sénégal
| | - Catherine Mazenot
- Institut de Recherche pour le Développement, Unité de Recherche sur les Maladies Infectieuses et Tropicales Emergentes (URMITE) UMR 198, Campus commun UCAD-IRD de Hann, BP 1386, CP 18524, Dakar, Sénégal
| | - Lassana Konate
- Laboratoire Ecologie Vectorielle et Parasitaire, UCAD, Fann Dakar, Sénégal
| | - Oumar Faye
- Laboratoire Ecologie Vectorielle et Parasitaire, UCAD, Fann Dakar, Sénégal
| | - Cheikh Sokhna
- Institut de Recherche pour le Développement, Unité de Recherche sur les Maladies Infectieuses et Tropicales Emergentes (URMITE) UMR 198, Campus commun UCAD-IRD de Hann, BP 1386, CP 18524, Dakar, Sénégal
- * E-mail:
| | - Jean-Francois Trape
- Institut de Recherche pour le Développement, Unité de Recherche sur les Maladies Infectieuses et Tropicales Emergentes (URMITE) UMR 198, Campus commun UCAD-IRD de Hann, BP 1386, CP 18524, Dakar, Sénégal
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Mourou JR, Coffinet T, Jarjaval F, Cotteaux C, Pradines E, Godefroy L, Kombila M, Pagès F. Malaria transmission in Libreville: results of a one year survey. Malar J 2012; 11:40. [PMID: 22321336 PMCID: PMC3310827 DOI: 10.1186/1475-2875-11-40] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2011] [Accepted: 02/09/2012] [Indexed: 11/13/2022] Open
Abstract
Background In Gabon, vector transmission has been poorly studied. Since the implementation of the Roll Back malaria recommendations, clinical studies have shown a decline in the burden of malaria in Libreville, the capital city of Gabon. To better understand the transmission dynamic in Libreville, an entomological survey was conducted in five districts of the city. Methods Mosquitoes were sampled by human landing collection during 1 year in five districts of Libreville: Alibandeng, Beauséjour, Camp des Boys and Sotega. Mosquitoes were identified morphologically and by molecular methods. The Plasmodium falciparum circumsporozoïte indices were measured by ELISA, and the entomological inoculation rates (EIR) were calculated for all areas. Molecular assessments of pyrethroid knock down resistance (kdr) and of insensitive acetylcholinesterase resistance were conducted. Results A total of 57,531 mosquitoes were caught during 341 person-nights (161 person-nights indoor and 180 person-nights outdoor) among which, 4,223 were Anopheles gambiae s.l. The average Human Biting Rate fell from 15.5 bites per person during the rainy season to 4.7 during the dry season. The An. gambiae complex population was composed of An. gambiae s.s molecular form S (99.5%), Anopheles melas (0.3%) and An. gambiae s.s. form M (0.2%). Thirty-three out of 4,223 An. gambiae s.l. were found to be infected by P. falciparum (CSP index = 0.78%). The annual EIR was estimated at 33.9 infected bites per person per year ranging from 13 in Alibandeng to 88 in Sotega. No insensitive AChE mutation was identified but both kdr-w and kdr-e mutations were present in An. gambiae molecular form S with a higher frequency of the kdr-w allele (76%) than the kdr-e allele (23.5%). Conclusion Malaria transmission in Libreville occurred mainly during the rainy season but also during the dry season in the five districts. Transmission level is high and seems to be very heterogeneous in the town. Interestingly, the highest EIR was recorded in the most central and urbanized quarter and the lowest in a peripheral area. The decrease of transmission usually seen from peri-urban areas to urban centers is probably more dependent of the socio-economic level of a quarter than of its location in the city. Urban malaria control programmes need to consider the socio economic level of an area rather than the location in the city in order to determine the areas most favourable to malaria transmission.
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Affiliation(s)
- Jean-Romain Mourou
- UMR 6236, Unité d'entomologie médicale, IRBA antenne Marseille, GSBDD Marseille Aubagne, 111 avenue de la corse BP 40026, 13568 Marseille Cedex 2, France
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Santolamazza F, Caputo B, Calzetta M, Vicente JL, Mancini E, Petrarca V, Pinto J, della Torre A. Comparative analyses reveal discrepancies among results of commonly used methods for Anopheles gambiaemolecular form identification. Malar J 2011; 10:215. [PMID: 21810255 PMCID: PMC3170251 DOI: 10.1186/1475-2875-10-215] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2011] [Accepted: 08/02/2011] [Indexed: 01/05/2023] Open
Abstract
BACKGROUND Anopheles gambiae M and S molecular forms, the major malaria vectors in the Afro-tropical region, are ongoing a process of ecological diversification and adaptive lineage splitting, which is affecting malaria transmission and vector control strategies in West Africa. These two incipient species are defined on the basis of single nucleotide differences in the IGS and ITS regions of multicopy rDNA located on the X-chromosome. A number of PCR and PCR-RFLP approaches based on form-specific SNPs in the IGS region are used for M and S identification. Moreover, a PCR-method to detect the M-specific insertion of a short interspersed transposable element (SINE200) has recently been introduced as an alternative identification approach. However, a large-scale comparative analysis of four widely used PCR or PCR-RFLP genotyping methods for M and S identification was never carried out to evaluate whether they could be used interchangeably, as commonly assumed. RESULTS The genotyping of more than 400 A. gambiae specimens from nine African countries, and the sequencing of the IGS-amplicon of 115 of them, highlighted discrepancies among results obtained by the different approaches due to different kinds of biases, which may result in an overestimation of MS putative hybrids, as follows: i) incorrect match of M and S specific primers used in the allele specific-PCR approach; ii) presence of polymorphisms in the recognition sequence of restriction enzymes used in the PCR-RFLP approaches; iii) incomplete cleavage during the restriction reactions; iv) presence of different copy numbers of M and S-specific IGS-arrays in single individuals in areas of secondary contact between the two forms. CONCLUSIONS The results reveal that the PCR and PCR-RFLP approaches most commonly utilized to identify A. gambiae M and S forms are not fully interchangeable as usually assumed, and highlight limits of the actual definition of the two molecular forms, which might not fully correspond to the two A. gambiae incipient species in their entire geographical range. These limits are discussed and operational suggestions on the choice of the most convenient method for large-scale M- and S-form identification are provided, also taking into consideration technical aspects related to the epidemiological characteristics of different study areas.
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Affiliation(s)
- Federica Santolamazza
- Istituto Pasteur-Fondazione Cenci-Bolognetti, Dipartimento di Sanità Pubblica e Malattie Infettive, Università SAPIENZA, Piazzale Aldo Moro 5, 00185, Rome, Italy
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