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Lugenge AG, Odufuwa OG, Mseti JJ, Swai JK, Skovmand O, Moore SJ. Complete series method (CSM): a convenient method to reduce daily heterogeneity when evaluating the regeneration time (RT) of insecticide-treated nets (ITNs). Parasit Vectors 2024; 17:235. [PMID: 38778423 PMCID: PMC11110420 DOI: 10.1186/s13071-024-06323-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2024] [Accepted: 05/13/2024] [Indexed: 05/25/2024] Open
Abstract
BACKGROUND "Regeneration time" (RT) denotes the time required to obtain a stable mortality rate for mosquitoes exposed to insecticide-treated nets (ITNs) after three consecutive washes of a net in a day. The RT informs the wash interval used to artificially age ITNs to simulate their lifetime performance under user conditions (20 washes). RT was estimated following World Health Organization (WHO) longitudinal method (LM) procedures. Longitudinal evaluation may introduce heterogeneity due to mosquito batch variability, complicating RT determination. To overcome this, nets at each stage of regeneration (i.e., 1, 2, 3, 5 and 7 days post wash) were prepared in advance and refrigerated; then, a complete regeneration series was tested with a single mosquito batch on 1 testing day, completing four series over 4 days. This study compared the complete series method (CSM) against the LM. METHODS The overall heterogeneity in the methods for estimating RT of one incorporated alpha-cypermethrin and piperonyl butoxide (PBO) and one incorporated permethrin with PBO ITNs was determined using laboratory-reared resistant Anopheles arabiensis under standard laboratory conditions. LM methods and CSM were compared in two experiments with refrigerated nets acclimated for (i) 2 h (test 1) and (ii) 3 h (test 2). Four regeneration replicates per day were tested per ITN product with 50 mosquitoes exposed per replicate (equivalent sample size to LM). The heterogeneity from these methods was compared descriptively. RESULTS The intra-method variability for unwashed pieces was minimal, with variance of 1.26 for CSM and 1.18 for LM. For unwashed nets, LM had substantially greater variance and ratio of LM:CSM was 2.66 in test 1 and 2.49 in test 2. The magnitude of mortality measured in bioassays depended on sample acclimation after refrigeration. CONCLUSIONS The CSM is a convenient method for determining the regeneration times. ITNs are prepared in advance, reducing pressure to prepare all samples to start on a single day. A complete regeneration series of samples is removed from the refrigerator, defrosted and evaluated on a single day with one mosquito batch reducing the influence of mosquito batch heterogeneity on results. Replicates can be conducted over several days but do not have to be conducted on consecutive days, allowing easy facility scheduling.
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Affiliation(s)
- Aidi Galus Lugenge
- Vector Control Product Testing Unit, Environmental Health and Ecological Science Department, Ifakara Health Institute, P.O. Box 74, Bagamoyo, Tanzania.
- School of Life Sciences and Bioengineering, The Nelson Mandela African Institution of Science and Technology (NM-AIST), P.O. Box 447, Arusha, Tanzania.
| | - Olukayode G Odufuwa
- Vector Control Product Testing Unit, Environmental Health and Ecological Science Department, Ifakara Health Institute, P.O. Box 74, Bagamoyo, Tanzania
- Vector Biology Unit, Epidemiology and Public Health Department, Swiss Tropical and Public Health Institute, Kreuzstrasse 2, Allschwil, 4123, Basel, Switzerland
- University of Basel, Petersplatz 1, 4001, Basel, Switzerland
- MRC International Statistics and Epidemiology Group, London School of Hygiene and Tropical Medicine (LSHTM), London, WC1E 7HT, UK
| | - Jilly Jackson Mseti
- Vector Control Product Testing Unit, Environmental Health and Ecological Science Department, Ifakara Health Institute, P.O. Box 74, Bagamoyo, Tanzania
- School of Life Sciences and Bioengineering, The Nelson Mandela African Institution of Science and Technology (NM-AIST), P.O. Box 447, Arusha, Tanzania
| | - Johnson Kyeba Swai
- Vector Control Product Testing Unit, Environmental Health and Ecological Science Department, Ifakara Health Institute, P.O. Box 74, Bagamoyo, Tanzania
- Vector Biology Unit, Epidemiology and Public Health Department, Swiss Tropical and Public Health Institute, Kreuzstrasse 2, Allschwil, 4123, Basel, Switzerland
- University of Basel, Petersplatz 1, 4001, Basel, Switzerland
| | | | - Sarah Jane Moore
- Vector Control Product Testing Unit, Environmental Health and Ecological Science Department, Ifakara Health Institute, P.O. Box 74, Bagamoyo, Tanzania
- School of Life Sciences and Bioengineering, The Nelson Mandela African Institution of Science and Technology (NM-AIST), P.O. Box 447, Arusha, Tanzania
- Vector Biology Unit, Epidemiology and Public Health Department, Swiss Tropical and Public Health Institute, Kreuzstrasse 2, Allschwil, 4123, Basel, Switzerland
- University of Basel, Petersplatz 1, 4001, Basel, Switzerland
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Paré PSL, Hien DFDS, Bayili K, Yerbanga RS, Cohuet A, Carrasco D, Guissou E, Gouagna LC, Yaméogo KB, Diabaté A, Ignell R, Dabiré RK, Lefèvre T, Gnankiné O. Natural plant diet impacts phenotypic expression of pyrethroid resistance in Anopheles mosquitoes. Sci Rep 2022; 12:21431. [PMID: 36509797 PMCID: PMC9744732 DOI: 10.1038/s41598-022-25681-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2022] [Accepted: 12/02/2022] [Indexed: 12/14/2022] Open
Abstract
Success in reducing malaria transmission through vector control is threatened by insecticide resistance in mosquitoes. Although the proximal molecular mechanisms and genetic determinants involved are well documented, little is known about the influence of the environment on mosquito resistance to insecticides. The aim of this study was to assess the effect of plant sugar feeding on the response of Anopheles gambiae sensu lato to insecticides. Adults were fed with one of four treatments, namely a 5% glucose control solution, nectariferous flowers of Barleria lupulina, of Cascabela thevetia and a combination of both B. lupulina + C. thevetia. WHO tube tests were performed with 0.05% and 0.5% deltamethrin, and knockdown rate (KD) and the 24 h mosquito mortality were measured. Plant diet significantly influenced mosquito KD rate at both concentrations of deltamethrin. Following exposure to 0.05% deltamethrin, the B. lupulina diet induced a 2.5 fold-increase in mosquito mortality compared to 5% glucose. Species molecular identification confirmed the predominance of An. gambiae (60% of the samples) over An. coluzzii and An. arabiensis in our study area. The kdr mutation L1014F displayed an allelic frequency of 0.75 and was positively associated with increased phenotypic resistance to deltamethrin. Plant diet, particularly B. lupulina, increased the susceptibility of mosquitoes to insecticides. The finding that B. lupulina-fed control individuals (i.e. not exposed to deltamethrin) also displayed increased 24 h mortality suggests that plant-mediated effects may be driven by a direct effect of plant diet on mosquito survival rather than indirect effects through interference with insecticide-resistance mechanisms. Thus, some plant species may weaken mosquitoes, making them less vigorous and more vulnerable to the insecticide. There is a need for further investigation, using a wider range of plant species and insecticides, in combination with other relevant environmental factors, to better understand the expression and evolution of insecticide resistance.
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Affiliation(s)
- Prisca S. L. Paré
- grid.457337.10000 0004 0564 0509Institut de Recherche en Sciences de la Santé (IRSS), Bobo-Dioulasso, Burkina Faso ,grid.462603.50000 0004 0382 3424MIVEGEC, Université de Montpellier, IRD, CNRS, Montpellier, France ,Laboratoire d’Entomologie Fondamentale et Appliquée (LEFA), Unité de Formation et de Recherche - Sciences de la Vie et de la Terre (UFR-SVT), Université Joseph KI-ZERBO (UJKZ), Ouagadougou, Burkina Faso
| | - Domonbabele F. D. S. Hien
- grid.457337.10000 0004 0564 0509Institut de Recherche en Sciences de la Santé (IRSS), Bobo-Dioulasso, Burkina Faso ,grid.462603.50000 0004 0382 3424MIVEGEC, Université de Montpellier, IRD, CNRS, Montpellier, France ,Laboratoire Mixte International sur les Vecteurs (LAMIVECT), Bobo-Dioulasso, Burkina Faso
| | - Koama Bayili
- grid.457337.10000 0004 0564 0509Institut de Recherche en Sciences de la Santé (IRSS), Bobo-Dioulasso, Burkina Faso
| | - Rakiswendé S. Yerbanga
- grid.457337.10000 0004 0564 0509Institut de Recherche en Sciences de la Santé (IRSS), Bobo-Dioulasso, Burkina Faso ,Laboratoire Mixte International sur les Vecteurs (LAMIVECT), Bobo-Dioulasso, Burkina Faso ,Institut des Sciences et Techniques (INSTech - BOBO), Bobo‑Dioulasso, Burkina Faso
| | - Anna Cohuet
- grid.462603.50000 0004 0382 3424MIVEGEC, Université de Montpellier, IRD, CNRS, Montpellier, France ,Laboratoire Mixte International sur les Vecteurs (LAMIVECT), Bobo-Dioulasso, Burkina Faso
| | - David Carrasco
- grid.462603.50000 0004 0382 3424MIVEGEC, Université de Montpellier, IRD, CNRS, Montpellier, France
| | - Edwige Guissou
- grid.457337.10000 0004 0564 0509Institut de Recherche en Sciences de la Santé (IRSS), Bobo-Dioulasso, Burkina Faso ,grid.462603.50000 0004 0382 3424MIVEGEC, Université de Montpellier, IRD, CNRS, Montpellier, France ,Laboratoire Mixte International sur les Vecteurs (LAMIVECT), Bobo-Dioulasso, Burkina Faso
| | - Louis-Clément Gouagna
- grid.462603.50000 0004 0382 3424MIVEGEC, Université de Montpellier, IRD, CNRS, Montpellier, France
| | - Koudraogo B. Yaméogo
- grid.457337.10000 0004 0564 0509Institut de Recherche en Sciences de la Santé (IRSS), Bobo-Dioulasso, Burkina Faso
| | - Abdoulaye Diabaté
- grid.457337.10000 0004 0564 0509Institut de Recherche en Sciences de la Santé (IRSS), Bobo-Dioulasso, Burkina Faso ,Laboratoire Mixte International sur les Vecteurs (LAMIVECT), Bobo-Dioulasso, Burkina Faso
| | - Rickard Ignell
- grid.6341.00000 0000 8578 2742Department of Plant Protection Biology, Unit of Chemical Ecology, Disease Vector Group, Swedish University of Agricultural Sciences, Uppsala, Sweden
| | - Roch K. Dabiré
- grid.457337.10000 0004 0564 0509Institut de Recherche en Sciences de la Santé (IRSS), Bobo-Dioulasso, Burkina Faso ,Laboratoire Mixte International sur les Vecteurs (LAMIVECT), Bobo-Dioulasso, Burkina Faso
| | - Thierry Lefèvre
- grid.462603.50000 0004 0382 3424MIVEGEC, Université de Montpellier, IRD, CNRS, Montpellier, France ,Laboratoire Mixte International sur les Vecteurs (LAMIVECT), Bobo-Dioulasso, Burkina Faso
| | - Olivier Gnankiné
- Laboratoire d’Entomologie Fondamentale et Appliquée (LEFA), Unité de Formation et de Recherche - Sciences de la Vie et de la Terre (UFR-SVT), Université Joseph KI-ZERBO (UJKZ), Ouagadougou, Burkina Faso
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Pinda PG, Msaky DS, Muyaga LL, Mshani IH, Njalambaha RM, Kihonda J, Bwanaly H, Ngowo HS, Kaindoa EW, Koekemoer LL, Okumu FO. Relationships between biological age, distance from aquatic habitats and pyrethroid resistance status of Anopheles funestus mosquitoes in south-eastern Tanzania. Malar J 2022; 21:365. [PMID: 36461058 PMCID: PMC9719249 DOI: 10.1186/s12936-022-04389-y] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2022] [Accepted: 11/16/2022] [Indexed: 12/05/2022] Open
Abstract
BACKGROUND Malaria transmission can be highly heterogeneous between and within localities, and is influenced by factors such as survival and biting frequencies of Anopheles mosquitoes. This study investigated the relationships between the biological age, distance from aquatic habitats and pyrethroid resistance status of Anopheles funestus mosquitoes, which currently dominate malaria transmission in south-east Tanzania. The study also examined how such relationships may influence malaria transmission and control. METHODS Female An. funestus were collected in houses located 50-100 m, 150-200 m or over 200 m from the nearest known aquatic habitats. The mosquitoes were exposed to 1×, 5× and 10× the diagnostic doses of deltamethrin or permethrin, or to the synergist, piperonyl butoxide (PBO) followed by the pyrethroids, then monitored for 24 h-mortality. Ovaries of exposed and non-exposed mosquitoes were dissected to assess parity as a proxy for biological age. Adults emerging from larval collections in the same villages were tested against the same insecticides at 3-5, 8-11 or 17-20 days old. FINDINGS Mosquitoes collected nearest to the aquatic habitats (50-100 m) had the lowest mortalities compared to other distances, with a maximum of 51% mortality at 10× permethrin. For the age-synchronized mosquitoes collected as larvae, the insecticide-induced mortality assessed at both the diagnostic and multiplicative doses (1×, 5× and 10×) increased with mosquito age. The highest mortalities at 1× doses were observed among the oldest mosquitoes (17-20 days). At 10× doses, mortalities were 99% (permethrin) and 76% (deltamethrin) among 8-11 day-olds compared to 80% (permethrin) and 58% (deltamethrin) among 3-5 day-olds. Pre-exposure to PBO increased the potency of both pyrethroids. The proportion of parous females was highest among mosquitoes collected farthest from the habitats. CONCLUSION In this specific setting, older An. funestus and those collected farthest from the aquatic habitats (near the centre of the village) were more susceptible to pyrethroids than the younger ones and those caught nearest to the habitats. These findings suggest that pyrethroid-based interventions may remain at least moderately effective despite widespread pyrethroid-resistance, by killing the older, less-resistant and potentially-infective mosquitoes. Further studies should investigate how and whether these observations could be exploited to optimize malaria control in different settings.
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Affiliation(s)
- Polius G Pinda
- Environmental Health and Ecological Sciences Department, Ifakara Health Institute, Morogoro, United Republic of Tanzania.
- School of Public Health, University of the Witwatersrand, Johannesburg, South Africa.
| | - Dickson S Msaky
- Environmental Health and Ecological Sciences Department, Ifakara Health Institute, Morogoro, United Republic of Tanzania
| | - Letus L Muyaga
- Environmental Health and Ecological Sciences Department, Ifakara Health Institute, Morogoro, United Republic of Tanzania
| | - Issa H Mshani
- Environmental Health and Ecological Sciences Department, Ifakara Health Institute, Morogoro, United Republic of Tanzania
- Institute of Biodiversity, Animal Health and Comparative Medicine, University of Glasgow, Glasgow, UK
| | - Rukiyah M Njalambaha
- Environmental Health and Ecological Sciences Department, Ifakara Health Institute, Morogoro, United Republic of Tanzania
| | - Japhet Kihonda
- Environmental Health and Ecological Sciences Department, Ifakara Health Institute, Morogoro, United Republic of Tanzania
| | - Hamis Bwanaly
- Environmental Health and Ecological Sciences Department, Ifakara Health Institute, Morogoro, United Republic of Tanzania
| | - Halfan S Ngowo
- Environmental Health and Ecological Sciences Department, Ifakara Health Institute, Morogoro, United Republic of Tanzania
- Institute of Biodiversity, Animal Health and Comparative Medicine, University of Glasgow, Glasgow, UK
| | - Emmanuel W Kaindoa
- Environmental Health and Ecological Sciences Department, Ifakara Health Institute, Morogoro, United Republic of Tanzania
- School of Life Sciences and Biotechnology, Nelson Mandela African Institution of Science and Technology, Arusha, United Republic of Tanzania
| | - Lizette L Koekemoer
- Wits Research Institute for Malaria, Faculty of Health Sciences, Centre for Emerging Zoonotic and Parasitic Diseases, University of the Witwatersrand, National Institute for Communicable Diseases, Johannesburg, South Africa
| | - Fredros O Okumu
- Environmental Health and Ecological Sciences Department, Ifakara Health Institute, Morogoro, United Republic of Tanzania.
- School of Life Sciences and Biotechnology, Nelson Mandela African Institution of Science and Technology, Arusha, United Republic of Tanzania.
- School of Public Health, University of the Witwatersrand, Johannesburg, South Africa.
- Institute of Biodiversity, Animal Health and Comparative Medicine, University of Glasgow, Glasgow, UK.
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4
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Omitting age-dependent mosquito mortality in malaria models underestimates the effectiveness of insecticide-treated nets. PLoS Comput Biol 2022; 18:e1009540. [PMID: 36121847 PMCID: PMC9522293 DOI: 10.1371/journal.pcbi.1009540] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2021] [Revised: 09/29/2022] [Accepted: 08/08/2022] [Indexed: 11/19/2022] Open
Abstract
Mathematical models of vector-borne infections, including malaria, often assume age-independent mortality rates of vectors, despite evidence that many insects senesce. In this study we present survival data on insecticide-resistant Anopheles gambiae s.l. from experiments in Côte d’Ivoire. We fit a constant mortality function and two age-dependent functions (logistic and Gompertz) to the data from mosquitoes exposed (treated) and not exposed (control) to insecticide-treated nets (ITNs), to establish biologically realistic survival functions. This enables us to explore the effects of insecticide exposure on mosquito mortality rates, and the extent to which insecticide resistance might impact the effectiveness of ITNs. We investigate this by calculating the expected number of infectious bites a mosquito will take in its lifetime, and by extension the vectorial capacity. Our results show that the predicted vectorial capacity is substantially lower in mosquitoes exposed to ITNs, despite the mosquitoes in the experiment being highly insecticide-resistant. The more realistic age-dependent functions provide a better fit to the experimental data compared to a constant mortality function and, hence, influence the predicted impact of ITNs on malaria transmission potential. In models with age-independent mortality, there is a great reduction for the vectorial capacity under exposure compared to no exposure. However, the two age-dependent functions predicted an even larger reduction due to exposure, highlighting the impact of incorporating age in the mortality rates. These results further show that multiple exposures to ITNs had a considerable effect on the vectorial capacity. Overall, the study highlights the importance of including age dependency in mathematical models of vector-borne disease transmission and in fully understanding the impact of interventions. Interventions against malaria are most commonly targeted on the adult mosquitoes, which transmit the infection from person to person. One of the most important interventions are bed-nets, treated with insecticides. Unfortunately, extensive exposure of mosquitoes to insecticide has led to widespread evolution of insecticide resistance, which might threaten control strategies. Piecing together the overall impact of resistance on the efficacy of insecticide-treated nets is complex, but can be informed by the use of mathematical models. However, there are some assumptions that the models frequently use which are not realistic in terms of the mosquito biology. In this paper, we formulate a model that includes age-dependent mortality rates, an important parameter in vector control since control strategies most commonly aim to reduce the lifespan of the mosquitoes. By using novel data collected using field-derived insecticide-resistant mosquitoes, we explore the effects that the presence of insecticides on nets have on the mortality rates, as well as the difference incorporating age dependency in the model has on the results. We find that including age-dependent mortality greatly alters the anticipated effects of insecticide-treated nets on mosquito transmission potential, and that ignoring this realism potentially overestimates the negative impact of insecticide resistance.
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Mbwambo SG, Bubun N, Mbuba E, Moore J, Mbina K, Kamande D, Laman M, Mpolya E, Odufuwa OG, Freeman T, Karl S, Moore SJ. Comparison of cone bioassay estimates at two laboratories with different Anopheles mosquitoes for quality assurance of pyrethroid insecticide-treated nets. Malar J 2022; 21:214. [PMID: 35799172 PMCID: PMC9264565 DOI: 10.1186/s12936-022-04217-3] [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: 01/17/2022] [Accepted: 06/11/2022] [Indexed: 11/16/2022] Open
Abstract
Background Quality assurance (QA) of insecticide-treated nets (ITNs) delivered to malaria-endemic countries is conducted by measuring physiochemical parameters, but not bioefficacy against malaria mosquitoes. This study explored utility of cone bioassays for pre-delivery QA of pyrethroid ITNs to test the assumption that cone bioassays are consistent across locations, mosquito strains, and laboratories. Methods Double-blinded bioassays were conducted on twenty unused pyrethroid ITNs of 4 brands (100 nets, 5 subsamples per net) that had been delivered for mass distribution in Papua New Guinea (PNG) having passed predelivery inspections. Cone bioassays were performed on the same net pieces following World Health Organization (WHO) guidelines at the PNG Institute of Medical Research (PNGIMR) using pyrethroid susceptible Anopheles farauti sensu stricto (s.s.) and at Ifakara Health Institute (IHI), Tanzania using pyrethroid susceptible Anopheles gambiae s.s. Additionally, WHO tunnel tests were conducted at IHI on ITNs that did not meet cone bioefficacy thresholds. Results from IHI and PNGIMR were compared using Spearman’s Rank correlation, Bland–Altman (BA) analysis and analysis of agreement. Literature review on the use of cone bioassays for unused pyrethroid ITNs testing was conducted. Results In cone bioassays, 13/20 nets (65%) at IHI and 8/20 (40%) at PNGIMR met WHO bioefficacy criteria. All nets met WHO bioefficacy criteria on combined cone/tunnel tests at IHI. Results from IHI and PNGIMR correlated on 60-min knockdown (KD60) (rs = 0.6,p = 0.002,n = 20) and 24-h mortality (M24) (rs = 0.9,p < 0.0001,n = 20) but BA showed systematic bias between the results. Of the 5 nets with discrepant result between IHI and PNGIMR, three had confidence intervals overlapping the 80% mortality threshold, with averages within 1–3% of the threshold. Including these as a pass, the agreement between the results to predict ITN failure was good with kappa = 0.79 (0.53–1.00) and 90% accuracy. Conclusions Based on these study findings, the WHO cone bioassay is a reproducible bioassay for ITNs with > 80% M24, and for all ITNs provided inherent stochastic variation and systematic bias are accounted for. The literature review confirms that WHO cone bioassay bioefficacy criteria have been previously achieved by all pyrethroid ITNs (unwashed), without the need for additional tunnel tests. The 80% M24 threshold remains the most reliable indicator of pyrethroid ITN quality using pyrethroid susceptible mosquitoes. In the absence of alternative tests, cone bioassays could be used as part of pre-delivery QA.
Supplementary Information The online version contains supplementary material available at 10.1186/s12936-022-04217-3.
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Affiliation(s)
- Stephen G Mbwambo
- Vector Control Product Testing Unit (VCPTU), Environmental Health and Ecological Science Department, Ifakara Health Institute, Bagamoyo, Tanzania. .,Nelson Mandela Africa Institution of Science and Technology, Arusha, Tanzania. .,Sokoine RRH, Ministry of Health, Lindi, Tanzania. .,Regional Health Management Team, P.O Box 1011, Lindi, Tanzania.
| | - Nakei Bubun
- Vector Borne Disease Unit, PNG Institute of Medical Research, Madang Province 511, P.O Box 378, Madang, Papua New Guinea
| | - Emmanuel Mbuba
- Vector Control Product Testing Unit (VCPTU), Environmental Health and Ecological Science Department, Ifakara Health Institute, Bagamoyo, Tanzania.,University of Basel, Basel, Switzerland.,Vector Biology Unit, Department of Epidemiology and Public Health, Swiss Tropical and Public Health Institute (Swiss TPH, Allschwil, Kreuzstrasse 2, 4123, , Basel, Switzerland
| | - Jason Moore
- Vector Control Product Testing Unit (VCPTU), Environmental Health and Ecological Science Department, Ifakara Health Institute, Bagamoyo, Tanzania.,Vector Biology Unit, Department of Epidemiology and Public Health, Swiss Tropical and Public Health Institute (Swiss TPH, Allschwil, Kreuzstrasse 2, 4123, , Basel, Switzerland
| | - Kasiani Mbina
- Vector Control Product Testing Unit (VCPTU), Environmental Health and Ecological Science Department, Ifakara Health Institute, Bagamoyo, Tanzania
| | - Dismas Kamande
- Vector Control Product Testing Unit (VCPTU), Environmental Health and Ecological Science Department, Ifakara Health Institute, Bagamoyo, Tanzania.,Nelson Mandela Africa Institution of Science and Technology, Arusha, Tanzania
| | - Moses Laman
- Vector Borne Disease Unit, PNG Institute of Medical Research, Madang Province 511, P.O Box 378, Madang, Papua New Guinea
| | - Emmanuel Mpolya
- Nelson Mandela Africa Institution of Science and Technology, Arusha, Tanzania
| | - Olukayode G Odufuwa
- Vector Control Product Testing Unit (VCPTU), Environmental Health and Ecological Science Department, Ifakara Health Institute, Bagamoyo, Tanzania.,University of Basel, Basel, Switzerland.,Vector Biology Unit, Department of Epidemiology and Public Health, Swiss Tropical and Public Health Institute (Swiss TPH, Allschwil, Kreuzstrasse 2, 4123, , Basel, Switzerland.,MRC International Statistics and Epidemiology Group, London School of Hygiene and Tropical Medicine, Keppel Street, London, WC1E 7HT, UK
| | - Tim Freeman
- Rotarian Against Malaria, P.O Box 3686, Boroko, NCD 111, Papua New Guinea
| | - Stephan Karl
- Vector Borne Disease Unit, PNG Institute of Medical Research, Madang Province 511, P.O Box 378, Madang, Papua New Guinea.,Australian Institute of Tropical Health and Medicine, James Cook University, 1/14-88 McGregor Road, Smithfield, QLD, 4870, Australia
| | - Sarah J Moore
- Vector Control Product Testing Unit (VCPTU), Environmental Health and Ecological Science Department, Ifakara Health Institute, Bagamoyo, Tanzania.,Nelson Mandela Africa Institution of Science and Technology, Arusha, Tanzania.,University of Basel, Basel, Switzerland.,Vector Biology Unit, Department of Epidemiology and Public Health, Swiss Tropical and Public Health Institute (Swiss TPH, Allschwil, Kreuzstrasse 2, 4123, , Basel, Switzerland
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Barreaux P, Koella JC, N'Guessan R, Thomas MB. Use of novel lab assays to examine the effect of pyrethroid-treated bed nets on blood-feeding success and longevity of highly insecticide-resistant Anopheles gambiae s.l. mosquitoes. Parasit Vectors 2022; 15:111. [PMID: 35346334 PMCID: PMC8962112 DOI: 10.1186/s13071-022-05220-y] [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: 09/19/2021] [Accepted: 02/24/2022] [Indexed: 11/28/2022] Open
Abstract
Background There is a pressing need to improve understanding of how insecticide resistance affects the functional performance of insecticide-treated nets (ITNs). Standard WHO insecticide resistance monitoring assays are designed for resistance surveillance and do not necessarily provide insight into how different frequencies, mechanisms or intensities of resistance affect the ability of ITNs to reduce malaria transmission. Methods The current study presents some novel laboratory-based assays that attempt to better simulate realistic exposure of mosquitoes to ITNs and to quantify impact of exposure not only on instantaneous mortality, but also on blood-feeding and longevity, two traits that are central to transmission. The assays evaluated the performance of a standard ITN (Permanet® 2.0; Vestergaard Frandsen), a ‘next generation’ combination ITN with a resistance-breaking synergist (Permanet® 3.0) and an untreated net (UTN), against field-derived Anopheles gambiae sensu lato mosquitoes from Côte d’Ivoire exhibiting a 1500-fold increase in pyrethroid resistance relative to a standard susceptible strain. Results The study revealed that the standard ITN induced negligible instantaneous mortality against the resistant mosquitoes, whereas the resistance-breaking net caused high mortality and a reduction in blood-feeding. However, both ITNs still impacted long-term survival relative to the UTN. The impact on longevity depended on feeding status, with blood-fed mosquitoes living longer than unfed mosquitoes following ITN exposure. Exposure to both ITNs also reduced the blood-feeding success, the time spent on the net and blood-feeding duration, relative to the untreated net. Conclusion Although a standard ITN did not have as substantial instantaneous impact as the resistance-breaking net, it still had significant impacts on traits important for transmission. These results highlight the benefit of improved bioefficacy assays that allow for realistic exposure and consider sub- or pre-lethal effects to help assess the functional significance of insecticide resistance. Graphical Abstract ![]()
Supplementary Information The online version contains supplementary material available at 10.1186/s13071-022-05220-y.
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Affiliation(s)
- Priscille Barreaux
- Liverpool School of Tropical Medicine, Liverpool, UK. .,Pennsylvania State University, State College, PA, USA. .,University of Neuchâtel, Neuchâtel, Switzerland.
| | | | - Raphael N'Guessan
- London School of Tropical Medicine, London, UK.,Vector Control Product Evaluation Centre, Institute Pierre Richet, Bouaké, Côte d'Ivoire
| | - Matthew B Thomas
- Pennsylvania State University, State College, PA, USA.,University of York, York, UK
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Lees RS, Praulins G, Lissenden N, South A, Carson J, Brown F, Lucas J, Malone D. The Residual Efficacy of SumiShield™ 50WG and K-Othrine® WG250 IRS Formulations Applied to Different Building Materials against Anopheles and Aedes Mosquitoes. INSECTS 2022; 13:insects13020112. [PMID: 35206686 PMCID: PMC8877416 DOI: 10.3390/insects13020112] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/16/2021] [Revised: 01/07/2022] [Accepted: 01/09/2022] [Indexed: 12/04/2022]
Abstract
Insecticides with novel modes of action are required to complement the pyrethroids currently relied upon for controlling malaria vectors. One example of this is the neonicotinoid clothianidin, the active ingredient in the indoor residual spray (IRS) SumiShield™ 50WG. In a preliminary experiment, the mortality of insecticide-susceptible and resistant An. gambiae adults exposed to filter papers treated with this IRS product reached 80% by 3 days post-exposure and 100% by 6 days post-exposure. Next, cement, wood, and mud tiles were treated with the clothianidin or a deltamethrin-based IRS formulation (K-Othrine WG250). Insecticide resistant and susceptible Anopheles and Aedes were exposed to these surfaces periodically for up to 18 months. Pyrethroid resistant Cx. quinquefasciatus was also exposed at 9 months. Between exposures, tiles were stored in heat and relative humidity conditions reflecting those found in the field. On these surfaces, the clothianidin IRS was effective at killing both susceptible and resistant An. gambiae for 18 months post-treatment, while mortality amongst the resistant strains when exposed to the deltamethrin IRS was not above that of the negative control. Greater efficacy of clothianidin was also demonstrated against insecticide resistant strains of An. funestus compared to deltamethrin, though the potency was lower when compared with An. gambiae. In general, higher efficacy of the clothianidin IRS was observed on cement and mud compared to wood, though it demonstrated poorer residual activity against Ae.aegypti and Cx. quinquefasciatus.
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Affiliation(s)
- Rosemary Susan Lees
- Vector Biology Department, Liverpool School of Tropical Medicine, Pembroke Place, Liverpool L3 5QA, UK; (G.P.); (N.L.); (A.S.); (J.C.); (F.B.)
- Liverpool Insect Testing Establishment (LITE), Liverpool School of Tropical Medicine, 1 Daulby Street, Liverpool L7 8XZ, UK
- Correspondence: ; Tel.: +44-(0)-151-705-3344
| | - Giorgio Praulins
- Vector Biology Department, Liverpool School of Tropical Medicine, Pembroke Place, Liverpool L3 5QA, UK; (G.P.); (N.L.); (A.S.); (J.C.); (F.B.)
| | - Natalie Lissenden
- Vector Biology Department, Liverpool School of Tropical Medicine, Pembroke Place, Liverpool L3 5QA, UK; (G.P.); (N.L.); (A.S.); (J.C.); (F.B.)
| | - Andy South
- Vector Biology Department, Liverpool School of Tropical Medicine, Pembroke Place, Liverpool L3 5QA, UK; (G.P.); (N.L.); (A.S.); (J.C.); (F.B.)
| | - Jessica Carson
- Vector Biology Department, Liverpool School of Tropical Medicine, Pembroke Place, Liverpool L3 5QA, UK; (G.P.); (N.L.); (A.S.); (J.C.); (F.B.)
- Liverpool Insect Testing Establishment (LITE), Liverpool School of Tropical Medicine, 1 Daulby Street, Liverpool L7 8XZ, UK
| | - Faye Brown
- Vector Biology Department, Liverpool School of Tropical Medicine, Pembroke Place, Liverpool L3 5QA, UK; (G.P.); (N.L.); (A.S.); (J.C.); (F.B.)
- Institute of Infection, Veterinary and Ecological Sciences, Department of Livestock and One Health, The University of Liverpool, Liverpool L69 3BX, UK
| | - John Lucas
- Environmental Health Division, Sumitomo Chemical (UK) plc, 200 Shepherds Bush Rd, London W6 7NL, UK;
| | - David Malone
- Innovative Vector Control Consortium (IVCC), Liverpool School of Tropical Medicine, Liverpool L3 5QA, UK;
- Bill & Melinda Gates Foundation, 500 5th Ave N, Seattle, WA 98109, USA
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Review of the ecology and behaviour of Aedes aegypti and Aedes albopictus in Western Africa and implications for vector control. CURRENT RESEARCH IN PARASITOLOGY & VECTOR-BORNE DISEASES 2022; 2:100074. [PMID: 35726222 PMCID: PMC7612875 DOI: 10.1016/j.crpvbd.2021.100074] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
Western Africa is vulnerable to arboviral disease transmission, having recently experienced major outbreaks of chikungunya, dengue, yellow fever and Zika. However, there have been relatively few studies on the natural history of the two major human arbovirus vectors in this region, Aedes aegypti and Ae. albopictus, potentially limiting the implementation of effective vector control. We systematically searched for and reviewed relevant studies on the behaviour and ecology of Ae. aegypti and Ae. albopictus in Western Africa, published over the last 40 years. We identified 73 relevant studies, over half of which were conducted in Nigeria, Senegal, or Côte d'Ivoire. Most studies investigated the ecology of Ae. aegypti and Ae. albopictus, exploring the impact of seasonality and land cover on mosquito populations and identifying aquatic habitats. This review highlights the adaptation of Ae. albopictus to urban environments and its invasive potential, and the year-round maintenance of Ae. aegypti populations in water storage containers. However, important gaps were identified in the literature on the behaviour of both species, particularly Ae. albopictus. In Western Africa, Ae. aegypti and Ae. albopictus appear to be mainly anthropophilic and to bite predominantly during the day, but further research is needed to confirm this to inform planning of effective vector control strategies. We discuss the public health implications of these findings and comment on the suitability of existing and novel options for control in Western Africa.
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Lissenden N, Kont MD, Essandoh J, Ismail HM, Churcher TS, Lambert B, Lenhart A, McCall PJ, Moyes CL, Paine MJI, Praulins G, Weetman D, Lees RS. Review and Meta-Analysis of the Evidence for Choosing between Specific Pyrethroids for Programmatic Purposes. INSECTS 2021; 12:insects12090826. [PMID: 34564266 PMCID: PMC8465213 DOI: 10.3390/insects12090826] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/05/2021] [Revised: 08/24/2021] [Accepted: 09/11/2021] [Indexed: 11/17/2022]
Abstract
Simple Summary A group of insecticides, called pyrethroids, are the main strategy for controlling the mosquito vectors of malaria. Pyrethroids are used in all insecticide-treated bednets, and many indoor residual spray programmes (in which insecticides are sprayed on the interior walls of houses). There are different types of pyrethroids within the class (e.g., deltamethrin and permethrin). Across the world, mosquitoes are showing signs of resistance to the pyrethroids, such as reduced mortality following contact. However, it is unclear if this resistance is uniform across the pyrethroid class (i.e., if a mosquito is resistant to deltamethrin, whether it is resistant to permethrin at the same level). In addition, it is not known if switching between different pyrethroids can be used to effectively maintain mosquito control when resistance to a single pyrethroid has been detected. This review examined the evidence from molecular studies, resistance testing from laboratory and field data, and mosquito behavioural assays to answer these questions. The evidence suggested that in areas where pyrethroid resistance exists, different mortality seen between the pyrethroids is not necessarily indicative of an operationally relevant difference in control performance, and there is no reason to rotate between common pyrethroids (i.e., deltamethrin, permethrin, and alpha-cypermethrin) as an insecticide resistance management strategy. Abstract Pyrethroid resistance is widespread in malaria vectors. However, differential mortality in discriminating dose assays to different pyrethroids is often observed in wild populations. When this occurs, it is unclear if this differential mortality should be interpreted as an indication of differential levels of susceptibility within the pyrethroid class, and if so, if countries should consider selecting one specific pyrethroid for programmatic use over another. A review of evidence from molecular studies, resistance testing with laboratory colonies and wild populations, and mosquito behavioural assays were conducted to answer these questions. Evidence suggested that in areas where pyrethroid resistance exists, different results in insecticide susceptibility assays with specific pyrethroids currently in common use (deltamethrin, permethrin, α-cypermethrin, and λ-cyhalothrin) are not necessarily indicative of an operationally relevant difference in potential performance. Consequently, it is not advisable to use rotation between these pyrethroids as an insecticide-resistance management strategy. Less commonly used pyrethroids (bifenthrin and etofenprox) may have sufficiently different modes of action, though further work is needed to examine how this may apply to insecticide resistance management.
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Affiliation(s)
- Natalie Lissenden
- Department of Vector Biology, Liverpool School of Tropical Medicine, Liverpool L3 5QA, UK; (N.L.); (J.E.); (H.M.I.); (P.J.M.); (M.J.I.P.); (G.P.); (D.W.)
| | - Mara D. Kont
- MRC Centre for Global Infectious Disease Analysis, School of Public Health, Imperial College London, London SW7 2BX, UK; (M.D.K.); (T.S.C.); (B.L.)
| | - John Essandoh
- Department of Vector Biology, Liverpool School of Tropical Medicine, Liverpool L3 5QA, UK; (N.L.); (J.E.); (H.M.I.); (P.J.M.); (M.J.I.P.); (G.P.); (D.W.)
| | - Hanafy M. Ismail
- Department of Vector Biology, Liverpool School of Tropical Medicine, Liverpool L3 5QA, UK; (N.L.); (J.E.); (H.M.I.); (P.J.M.); (M.J.I.P.); (G.P.); (D.W.)
| | - Thomas S. Churcher
- MRC Centre for Global Infectious Disease Analysis, School of Public Health, Imperial College London, London SW7 2BX, UK; (M.D.K.); (T.S.C.); (B.L.)
| | - Ben Lambert
- MRC Centre for Global Infectious Disease Analysis, School of Public Health, Imperial College London, London SW7 2BX, UK; (M.D.K.); (T.S.C.); (B.L.)
| | - Audrey Lenhart
- U.S. Centers for Disease Control and Prevention, Entomology Branch, Division of Parasitic Diseases and Malaria, Atlanta, GA 30329, USA;
| | - Philip J. McCall
- Department of Vector Biology, Liverpool School of Tropical Medicine, Liverpool L3 5QA, UK; (N.L.); (J.E.); (H.M.I.); (P.J.M.); (M.J.I.P.); (G.P.); (D.W.)
| | | | - Mark J. I. Paine
- Department of Vector Biology, Liverpool School of Tropical Medicine, Liverpool L3 5QA, UK; (N.L.); (J.E.); (H.M.I.); (P.J.M.); (M.J.I.P.); (G.P.); (D.W.)
| | - Giorgio Praulins
- Department of Vector Biology, Liverpool School of Tropical Medicine, Liverpool L3 5QA, UK; (N.L.); (J.E.); (H.M.I.); (P.J.M.); (M.J.I.P.); (G.P.); (D.W.)
| | - David Weetman
- Department of Vector Biology, Liverpool School of Tropical Medicine, Liverpool L3 5QA, UK; (N.L.); (J.E.); (H.M.I.); (P.J.M.); (M.J.I.P.); (G.P.); (D.W.)
| | - Rosemary S. Lees
- Department of Vector Biology, Liverpool School of Tropical Medicine, Liverpool L3 5QA, UK; (N.L.); (J.E.); (H.M.I.); (P.J.M.); (M.J.I.P.); (G.P.); (D.W.)
- Correspondence: ; Tel.: +44-(0)-151-705-3344
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Rocha-Santos C, Dutra ACVPL, Fróes Santos R, Cupolillo CDLS, de Melo Rodovalho C, Bellinato DF, Dos Santos Dias L, Jablonka W, Lima JBP, Silva Neto MAC, Atella GC. Effect of Larval Food Availability on Adult Aedes Aegypti (Diptera: Culicidae) Fitness and Susceptibility to Zika Infection. JOURNAL OF MEDICAL ENTOMOLOGY 2021; 58:535-547. [PMID: 33219384 DOI: 10.1093/jme/tjaa249] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/25/2020] [Indexed: 06/11/2023]
Abstract
Aedes (Stegomyia) aegypti (Linnaeus, 1762) is a mosquito species of significant medical importance. The use of this vector in research studies usually requires a large number of mosquitoes as well as rearing and maintenance in a laboratory-controlled environment. However, laboratory conditions may be different from field environments, presenting stressful challenges such as low food concentration, especially during larval stages, which may, in turn, impair vector biology. Therefore, we tested herein if larval food availability (0.004, 0.009, 0.020, and 0.070% diets) would affect overall adult insect fitness. We observed slower development in mosquitoes fed a 0.004% diet 15 d post-eclosion (DPE) and shorter mean time in mosquitoes fed a 0.020% diet (7 DPE). Larval diet and adult mosquito weight were positively correlated, and heavier females fed higher larval diets exhibited greater blood feeding capacity and oviposition. In addition, larval diet concentrations led to median adult lifespan variations (male/female in days-0.004%: 30 ± 1.41, 45 ± 1.3; 0.009%: 31.5 ± 1.33, 41 ± 1.43; 0.020%: 26 ± 1.18, 41 ± 1.45; 0.070%: 29 ± 1.07, 44 ± 1.34), reduced tolerance to deltamethrin (1 mg/m2) and changes in detoxification enzyme activities. Moreover, in the larval 0.070% diet, females presented higher Zika susceptibility (plaque-forming unit [PFU]: 1.218 × 106) compared with other diets (0.004%: 1.31 × 105; 0.009%: 2.0 × 105; 0.020%: 1.25 × 105 PFU). Altogether, our study demonstrates that larval diet restriction results not only in larval developmental arrest but also in adult fitness impairment, which must be considered in future assessments.
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Affiliation(s)
- Carlucio Rocha-Santos
- Laboratório de Sinalização Celular Programa de Biologia Molecular e Biotecnologia, Instituto de Bioquímica Médica Leopoldo de Meis, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ, Brazil
- Laboratório de Fisiologia e Controle de Artrópodes Vetores, Instituto Oswaldo Cruz, Fiocruz, Rio de Janeiro, RJ, Brazil
- Laboratório de Entomologia, Instituto de Biologia do Exército, Rio de Janeiro, RJ, Brazil
| | - Ana Cristina Vieira Paes Leme Dutra
- Laboratório de Sinalização Celular Programa de Biologia Molecular e Biotecnologia, Instituto de Bioquímica Médica Leopoldo de Meis, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ, Brazil
- Laboratório de Bioquímica de Lipídios e Lipoproteínas, Programa de Biologia Molecular e Biotecnologia, Instituto de Bioquímica Médica Leopoldo de Meis, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ, Brazil
| | - Rogério Fróes Santos
- Laboratório de Sinalização Celular Programa de Biologia Molecular e Biotecnologia, Instituto de Bioquímica Médica Leopoldo de Meis, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ, Brazil
- Fundação CECIERJ/Consórcio CEDERJ, Polo Campo Grande, Rio de Janeiro, RJ, Brazil
| | - Catharina D'Oliveira Loures Schwartz Cupolillo
- Laboratório de Sinalização Celular Programa de Biologia Molecular e Biotecnologia, Instituto de Bioquímica Médica Leopoldo de Meis, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ, Brazil
- Laboratório de Bioquímica de Lipídios e Lipoproteínas, Programa de Biologia Molecular e Biotecnologia, Instituto de Bioquímica Médica Leopoldo de Meis, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ, Brazil
| | - Cynara de Melo Rodovalho
- Laboratório de Fisiologia e Controle de Artrópodes Vetores, Instituto Oswaldo Cruz, Fiocruz, Rio de Janeiro, RJ, Brazil
- Laboratório de Entomologia, Instituto de Biologia do Exército, Rio de Janeiro, RJ, Brazil
| | - Diogo Fernandes Bellinato
- Laboratório de Fisiologia e Controle de Artrópodes Vetores, Instituto Oswaldo Cruz, Fiocruz, Rio de Janeiro, RJ, Brazil
- Laboratório de Entomologia, Instituto de Biologia do Exército, Rio de Janeiro, RJ, Brazil
| | - Luciana Dos Santos Dias
- Laboratório de Fisiologia e Controle de Artrópodes Vetores, Instituto Oswaldo Cruz, Fiocruz, Rio de Janeiro, RJ, Brazil
- Laboratório de Entomologia, Instituto de Biologia do Exército, Rio de Janeiro, RJ, Brazil
| | - Willy Jablonka
- Laboratório de Sinalização Celular Programa de Biologia Molecular e Biotecnologia, Instituto de Bioquímica Médica Leopoldo de Meis, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ, Brazil
- Laboratório de Bioquímica de Lipídios e Lipoproteínas, Programa de Biologia Molecular e Biotecnologia, Instituto de Bioquímica Médica Leopoldo de Meis, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ, Brazil
| | - José Bento Pereira Lima
- Laboratório de Fisiologia e Controle de Artrópodes Vetores, Instituto Oswaldo Cruz, Fiocruz, Rio de Janeiro, RJ, Brazil
- Laboratório de Entomologia, Instituto de Biologia do Exército, Rio de Janeiro, RJ, Brazil
| | - Mário Alberto Cardoso Silva Neto
- Laboratório de Sinalização Celular Programa de Biologia Molecular e Biotecnologia, Instituto de Bioquímica Médica Leopoldo de Meis, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ, Brazil
| | - Georgia Correa Atella
- Laboratório de Bioquímica de Lipídios e Lipoproteínas, Programa de Biologia Molecular e Biotecnologia, Instituto de Bioquímica Médica Leopoldo de Meis, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ, Brazil
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Blouquy L, Mottet C, Olivares J, Plantamp C, Siegwart M, Barrès B. How varying parameters impact insecticide resistance bioassay: An example on the worldwide invasive pest Drosophila suzukii. PLoS One 2021; 16:e0247756. [PMID: 33667239 PMCID: PMC7935283 DOI: 10.1371/journal.pone.0247756] [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: 05/04/2020] [Accepted: 02/12/2021] [Indexed: 11/18/2022] Open
Abstract
Monitoring pesticide resistance is essential for effective and sustainable agricultural practices. Bioassays are the basis for pesticide-resistance testing, but devising a reliable and reproducible method can be challenging because these tests are carried out on living organisms. Here, we investigated five critical parameters and how they affected the evaluation of resistance to the organophosphate phosmet or the pyrethroid lambda-cyhalothrin using a tarsal-contact protocol on Drosophila suzukii, a worldwide invasive pest. Three of the parameters were related to insect biology: (i) sex, (ii) age of the imago (adult stage) and (iii) genetic diversity of the tested population. The two remaining parameters were linked to the experimental setup: (iv) the number of individuals tested per dose and (v) the duration of exposure to the active ingredient. Results showed that response to insecticide differed depending on sex, males being twice as susceptible to phosmet as females. Age principally affected young females' susceptibility to phosmet, because 0-24 hour-old flies were twice as susceptible as 24-48 hour-old and 72-96 hour-old females. Genetic diversity had no observable effect on resistance levels. The precision and accuracy of the median lethal dose (LD50) were greatly affected by the number of individuals tested per dose with a threshold effect. Finally, optimal duration of exposure to the active ingredient was 24 h, as we found an underestimation of mortality when assessed between 1 and 5 h after exposure to lambda-cyhalothrin. None of the main known point mutations on the para sodium channel gene associated with a knockdown effect were observed. Our study demonstrates the importance of calibrating the various parameters of a bioassay to develop a reliable method. It also provides a valuable and transferable protocol for monitoring D. suzukii resistance worldwide.
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Affiliation(s)
- Lucile Blouquy
- Université de Lyon, Anses, INRAE, USC CASPER, Lyon, France
- PSH - Unité de recherche Plantes et Systèmes de Culture Horticoles, INRAE, Avignon, France
| | - Claire Mottet
- Université de Lyon, Anses, INRAE, USC CASPER, Lyon, France
| | - Jérôme Olivares
- PSH - Unité de recherche Plantes et Systèmes de Culture Horticoles, INRAE, Avignon, France
| | | | - Myriam Siegwart
- PSH - Unité de recherche Plantes et Systèmes de Culture Horticoles, INRAE, Avignon, France
| | - Benoit Barrès
- Université de Lyon, Anses, INRAE, USC CASPER, Lyon, France
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Benedict MQ, Bascuñán P, Hunt CM, Aviles EI, Rotenberry RD, Dotson EM. Trials of the Automated Particle Counter for laboratory rearing of mosquito larvae. PLoS One 2020; 15:e0241492. [PMID: 33170865 PMCID: PMC7654806 DOI: 10.1371/journal.pone.0241492] [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: 08/03/2020] [Accepted: 10/15/2020] [Indexed: 11/18/2022] Open
Abstract
As a means of obtaining reproducible and accurate numbers of larvae for laboratory rearing, we tested a large-particle flow-cytometer type device called the ‘Automated Particle Counter’ (APC). The APC is a gravity-fed, self-contained unit that detects changes in light intensity caused by larvae passing the detector in a water stream and controls dispensing by stopping the flow when the desired number has been reached. We determined the accuracy (number dispensed compared to the target value) and precision (distribution of number dispensed) of dispensing at a variety of counting sensitivity thresholds and larva throughput rates (larvae per second) using < 1-day old Anopheles gambiae and Aedes aegypti larvae. All measures were made using an APC algorithm called the ‘Smoothed Z-Score’ which allows the user to define how many standard deviations (Z scores) from the baseline light intensity a particle’s absorbance must exceed to register a count. We dispensed a target number of 100 An. gambiae larvae using Z scores from 2.5–8 and observed no difference among them in the numbers dispensed for scores from 2.5–6, however, scores of 7 and 8 under-counted (over-dispensed) larvae. Using a Z score ≤ 6, we determined the effect of throughput rate on the accuracy of the device to dispense An. gambiae larvae. For rates ≤ 98 larvae per second, the accuracy of dispensing a target of 100 larvae was - 2.29% ± 0.72 (95% CI of the mean) with a mode of 99 (49 of 348 samples). When using a Z score of 3.5 and rates ≤ 100 larvae per second, the accuracy of dispensing a target of 100 Ae. aegypti was - 2.43% ± 1.26 (95% CI of the mean) with a mode of 100 (6 of 42 samples). No effect on survival was observed on the number of An. gambiae first stage larvae that reached adulthood as a function of dispensing.
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Affiliation(s)
- Mark Q. Benedict
- Entomology Branch, Division of Parasitic Diseases and Malaria, Centers for Disease Control and Prevention (CDC), Atlanta, GA, United States of America
- * E-mail:
| | - Priscila Bascuñán
- Entomology Branch, Division of Parasitic Diseases and Malaria, Centers for Disease Control and Prevention (CDC), Atlanta, GA, United States of America
| | - Catherine M. Hunt
- Entomology Branch, Division of Parasitic Diseases and Malaria, Centers for Disease Control and Prevention (CDC), Atlanta, GA, United States of America
| | - Erica I. Aviles
- Entomology Branch, Division of Parasitic Diseases and Malaria, Centers for Disease Control and Prevention (CDC), Atlanta, GA, United States of America
| | - Rachel D. Rotenberry
- Entomology Branch, Division of Parasitic Diseases and Malaria, Centers for Disease Control and Prevention (CDC), Atlanta, GA, United States of America
| | - Ellen M. Dotson
- Entomology Branch, Division of Parasitic Diseases and Malaria, Centers for Disease Control and Prevention (CDC), Atlanta, GA, United States of America
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Pinda PG, Eichenberger C, Ngowo HS, Msaky DS, Abbasi S, Kihonda J, Bwanaly H, Okumu FO. Comparative assessment of insecticide resistance phenotypes in two major malaria vectors, Anopheles funestus and Anopheles arabiensis in south-eastern Tanzania. Malar J 2020; 19:408. [PMID: 33176805 PMCID: PMC7661194 DOI: 10.1186/s12936-020-03483-3] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2020] [Accepted: 11/05/2020] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Long-lasting insecticide-treated nets (LLINs) and indoor residual spraying (IRS) have greatly reduced malaria transmission in sub-Saharan Africa, but are threatened by insecticide resistance. In south-eastern Tanzania, pyrethroid-resistant Anopheles funestus are now implicated in > 80% of malaria infections, even in villages where the species occurs at lower densities than the other vector, Anopheles arabiensis. This study compared the insecticide resistance phenotypes between the two malaria vectors in an area where pyrethroid-LLINs are widely used. METHODS The study used the World Health Organization (WHO) assays with 1×, 5× and 10× insecticide doses to assess levels of resistance, followed by synergist bioassays to understand possible mechanisms of the observed resistance phenotypes. The tests involved adult mosquitoes collected from three villages across two districts in south-eastern Tanzania and included four insecticide classes. FINDINGS At baseline doses (1×), both species were resistant to the two candidate pyrethroids (permethrin and deltamethrin), but susceptible to the organophosphate (pirimiphos-methyl). Anopheles funestus, but not An. arabiensis was also resistant to the carbamate (bendiocarb). Both species were resistant to DDT in all villages except in one village where An. arabiensis was susceptible. Anopheles funestus showed strong resistance to pyrethroids, surviving the 5× and 10× doses, while An. arabiensis reverted to susceptibility at the 5× dose. Pre-exposure to the synergist, piperonyl butoxide (PBO), enhanced the potency of the pyrethroids against both species and resulted in full susceptibility of An. arabiensis (> 98% mortality). However, for An. funestus from two villages, permethrin-associated mortalities after pre-exposure to PBO only exceeded 90% but not 98%. CONCLUSIONS In south-eastern Tanzania, where An. funestus dominates malaria transmission, the species also has much stronger resistance to pyrethroids than its counterpart, An. arabiensis, and can survive more classes of insecticides. The pyrethroid resistance in both species appears to be mostly metabolic and may be partially addressed using synergists, e.g. PBO. These findings may explain the continued persistence and dominance of An. funestus despite widespread use of pyrethroid-treated LLINs, and inform new intervention choices for such settings. In short and medium-term, these may include PBO-based LLINs or improved IRS with compounds to which the vectors are still susceptible.
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Affiliation(s)
- Polius G Pinda
- Environmental Health and Ecological Sciences Department, Ifakara Health Institute, Morogoro, United Republic of Tanzania.
| | - Claudia Eichenberger
- Environmental Health and Ecological Sciences Department, Ifakara Health Institute, Morogoro, United Republic of Tanzania.,Swiss Tropical and Public Health Institute, Basel, Switzerland
| | - Halfan S Ngowo
- Environmental Health and Ecological Sciences Department, Ifakara Health Institute, Morogoro, United Republic of Tanzania.,Institute of Biodiversity, Animal Health and Comparative Medicine, University of Glasgow, Glasgow, UK
| | - Dickson S Msaky
- Environmental Health and Ecological Sciences Department, Ifakara Health Institute, Morogoro, United Republic of Tanzania
| | - Said Abbasi
- Environmental Health and Ecological Sciences Department, Ifakara Health Institute, Morogoro, United Republic of Tanzania
| | - Japhet Kihonda
- Environmental Health and Ecological Sciences Department, Ifakara Health Institute, Morogoro, United Republic of Tanzania
| | - Hamis Bwanaly
- Environmental Health and Ecological Sciences Department, Ifakara Health Institute, Morogoro, United Republic of Tanzania
| | - Fredros O Okumu
- Environmental Health and Ecological Sciences Department, Ifakara Health Institute, Morogoro, United Republic of Tanzania. .,Nelson Mandela African Institution of Science and Technology, School of Life Sciences and Biotechnology, Arusha, United Republic of Tanzania. .,School of Public Health, University of the Witwatersrand, Parktown, South Africa. .,Institute of Biodiversity, Animal Health and Comparative Medicine, University of Glasgow, Glasgow, UK.
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Okumu F. The fabric of life: what if mosquito nets were durable and widely available but insecticide-free? Malar J 2020; 19:260. [PMID: 32690016 PMCID: PMC7370456 DOI: 10.1186/s12936-020-03321-6] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2020] [Accepted: 07/04/2020] [Indexed: 11/20/2022] Open
Abstract
BACKGROUND Bed nets are the commonest malaria prevention tool and arguably the most cost-effective. Their efficacy is because they prevent mosquito bites (a function of physical durability and integrity), and kill mosquitoes (a function of chemical content and mosquito susceptibility). This essay follows the story of bed nets, insecticides and malaria control, and asks whether the nets must always have insecticides. METHODS Key attributes of untreated or pyrethroid-treated nets are examined alongside observations of their entomological and epidemiological impacts. Arguments for and against adding insecticides to nets are analysed in contexts of pyrethroid resistance, personal-versus-communal protection, outdoor-biting, need for local production and global health policies. FINDINGS Widespread resistance in African malaria vectors has greatly weakened the historical mass mosquitocidal effects of insecticide-treated nets (ITNs), which previously contributed communal benefits to users and non-users. Yet ITNs still achieve substantial epidemiological impact, suggesting that physical integrity, consistent use and population-level coverage are increasingly more important than mosquitocidal properties. Pyrethroid-treatment remains desirable where vectors are sufficiently susceptible, but is no longer universally necessary and should be re-examined alongside other attributes, e.g. durability, coverage, acceptability and access. New ITNs with multiple actives or synergists could provide temporary relief in some settings, but their performance, higher costs, and drawn-out innovation timelines do not justify singular emphasis on insecticides. Similarly, sub-lethal insecticides may remain marginally-impactful by reducing survival of older mosquitoes and disrupting parasite development inside the mosquitoes, but such effects vanish under strong resistance. CONCLUSIONS The public health value of nets is increasingly driven by bite prevention, and decreasingly by lethality to mosquitoes. For context-appropriate solutions, it is necessary to acknowledge and evaluate the potential and cost-effectiveness of durable untreated nets across different settings. Though ~ 90% of malaria burden occurs in Africa, most World Health Organization-prequalified nets are manufactured outside Africa, since many local manufacturers lack capacity to produce the recommended insecticidal nets at competitive scale and pricing. By relaxing conditions for insecticides on nets, it is conceivable that non-insecticidal but durable, and possibly bio-degradable nets, could be readily manufactured locally. This essay aims not to discredit ITNs, but to illustrate how singular focus on insecticides can hinder innovation and sustainability.
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Affiliation(s)
- Fredros Okumu
- Environmental Health & Ecological Sciences, Ifakara Health Institute, Ifakara, Tanzania.
- School of Public Health, University of the Witwatersrand, Johannesburg, Republic of South Africa.
- Institute of Biodiversity, Animal Health & Comparative Medicine, University of Glasgow, Glasgow, UK.
- School of Life Science and Bioengineering, Nelson Mandela African Institution of Science & Technology, Arusha, Tanzania.
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Pires S, Alves J, Dia I, Gómez LF. Susceptibility of mosquito vectors of the city of Praia, Cabo Verde, to Temephos and Bacillus thuringiensis var israelensis. PLoS One 2020; 15:e0234242. [PMID: 32520941 PMCID: PMC7286513 DOI: 10.1371/journal.pone.0234242] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2019] [Accepted: 05/21/2020] [Indexed: 11/18/2022] Open
Abstract
Many vector-borne diseases circulate in the Republic of Cabo Verde. These include malaria during the colonization of the archipelago by the Portuguese explorers and several arboviruses such as yellow fever (now eradicated), dengue and zika. To control these vector-borne diseases, an integrated vector control program was implemented. The main targeted mosquito vectors are Aedes aegypti and Anopheles arabiensis, and in a lesser extent the potential arbovirus vector Culex pipiens s.l. The main control strategy is focused on mosquito aquatic stages using diesel oil and Temephos. This latter has been applied in Cabo Verde since 1979. Its continuous use was followed by the emergence of resistance in mosquito populations. We investigated the current susceptibility to Temephos of the three potential mosquito vectors of Cabo Verde through bioassays tests. Our results showed various degrees of susceptibility with 24h post-exposure mortality rates ranging from 43.1% to 90.9% using WHO diagnostic doses. A full susceptibility was however observed with Bacillus thurigiensis var israelensis with mortality rates from 99.6% to 100%.
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Affiliation(s)
- Sílvia Pires
- Unidade de Ciências da Natureza, da Vida e do Ambiente, Universidade Jean Piaget de Cabo Verde, Praia, Cabo Verde
| | - Joana Alves
- Instituto Nacional de Saúde Pública, Ministério da Saúde, Praia, Cabo Verde
| | - Ibrahima Dia
- Unité d’entomologie médicale, Institut Pasteur de Dakar, Dakar, Senegal
| | - Lara F. Gómez
- Unidade de Ciências da Natureza, da Vida e do Ambiente, Universidade Jean Piaget de Cabo Verde, Praia, Cabo Verde
- * E-mail:
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Hauser G, Thiévent K, Koella JC. Consequences of larval competition and exposure to permethrin for the development of the rodent malaria Plasmodium berghei in the mosquito Anopheles gambiae. Parasit Vectors 2020; 13:107. [PMID: 32106886 PMCID: PMC7045583 DOI: 10.1186/s13071-020-3983-9] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2019] [Accepted: 02/18/2020] [Indexed: 01/16/2023] Open
Abstract
Background Mosquitoes and other vectors are often exposed to sublethal doses of insecticides. Larvae can be exposed to the run-off of agricultural use, and adults can be irritated by insecticides used against them and move away before they have picked up a lethal dose. This sublethal exposure may affect the success of control of insect-borne diseases, for it may affect the competence of insects to transmit parasites, in particular if the insects are undernourished. Methods We assessed how exposure of larvae and adults to a sublethal dose of permethrin (a pyrethroid) and how larval competition for food affect several aspects of the vector competence of the mosquito Anopheles gambiae for the malaria parasite Plasmodium berghei. We infected mosquitoes with P. berghei and measured the longevity and the prevalence and intensity of infection to test for an effect of our treatments. Results Our general result was that the exposure to the insecticide helped mosquitoes deal with infection by malaria. Exposure of either larvae or adults decreased the likelihood that mosquitoes were infected by about 20%, but did not effect the parasite load. Exposure also increased the lifespan of infected mosquitoes, but only if they had been reared in competition. Larval competition had no effect on the prevalence of infection, but increased parasite load. These effects may be a consequence of the machinery governing oxidative stress, which underlies the responses of mosquitoes to insecticides, to food stress and to parasites. Conclusions We conclude that insecticide residues are likely to affect the ability of mosquitoes to carry and transmit pathogens such as malaria, irrespective of the stage at which they are exposed to the insecticide. Our results stress the need for further studies to consider sublethal doses in the context of vector ecology and vector-borne disease epidemiology.![]()
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Affiliation(s)
- Gaël Hauser
- Institute of Biology, University of Neuchâtel, Rue Emile-Argand 11, 2000, Neuchâtel, Switzerland.
| | - Kevin Thiévent
- Institute of Biology, University of Neuchâtel, Rue Emile-Argand 11, 2000, Neuchâtel, Switzerland
| | - Jacob C Koella
- Institute of Biology, University of Neuchâtel, Rue Emile-Argand 11, 2000, Neuchâtel, Switzerland
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Larval exposure to a pyrethroid insecticide and competition for food modulate the melanisation and antibacterial responses of adult Anopheles gambiae. Sci Rep 2020; 10:1364. [PMID: 31992835 PMCID: PMC6987095 DOI: 10.1038/s41598-020-58415-7] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2019] [Accepted: 01/08/2020] [Indexed: 12/27/2022] Open
Abstract
The insecticides we use for agriculture and for vector control often arrive in water bodies, where mosquito larvae may be exposed to them. Not only will they then likely affect the development of the larvae, but their effects may carry over to the adults, potentially affecting their capacity at transmitting infectious diseases. Such an impact may be expected to be more severe when mosquitoes are undernourished. In this study, we investigated whether exposing larvae of the mosquito Anopheles gambiae to a sub-lethal dose of permethrin (a pyrethroid) and forcing them to compete for food would affect the immune response of the adults. We found that a low dose of permethrin increased the degree to which individually reared larvae melanised a negatively charged Sephadex bead and slowed the replication of injected Escherichia coli. However, if mosquitoes had been reared in groups of three (and thus had been forced to compete for food) permethrin had less impact on the efficacy of the immune responses. Our results show how larval stressors can affect the immune response of adults, and that the outcome of exposure to insecticides strongly depends on environmental conditions.
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Thiévent K, Zilio G, Hauser G, Koella JC. Malaria load affects the activity of mosquito salivary apyrase. JOURNAL OF INSECT PHYSIOLOGY 2019; 116:10-16. [PMID: 30986373 DOI: 10.1016/j.jinsphys.2019.04.003] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/22/2018] [Revised: 04/10/2019] [Accepted: 04/11/2019] [Indexed: 06/09/2023]
Abstract
Mosquitoes infected by sporozoites, the infectious stage of malaria, bite more frequently than uninfected mosquitoes. One of the mechanisms underlying this behavioural change appears to be that the sporozoites decrease the activity of apyrase, an ADP-degrading enzyme that helps the mosquitoes to locate blood. Using the parasite Plasmodium berghei and the mosquito Anopheles gambiae, we confirmed that sporozoite infection alters the host-seeking behaviour of mosquitoes by making them more likely to refeed after a first blood meal, and that apyrase activity is one of the mechanisms of the increased biting persistence and motivation of infectious mosquitoes. We further showed that apyrase activity decreases as the sporozoite load increases, and that mosquitoes with lower apyrase activity take up less blood, making it more likely that they would return to top up their blood meal. Finally, by comparing full-sib families of mosquitoes, we showed that there was genetic variation for apyrase activity, but not for the resistance of parasites to be manipulated. Our results give new insights in understanding how malaria parasites change their hosts to affect their own transmission.
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Affiliation(s)
- Kevin Thiévent
- Institute of Biology, University of Neuchâtel, Rue Emile-Argand 11, 2000 Neuchâtel, Switzerland.
| | - Giacomo Zilio
- Institute of Biology, University of Neuchâtel, Rue Emile-Argand 11, 2000 Neuchâtel, Switzerland
| | - Gaël Hauser
- Institute of Biology, University of Neuchâtel, Rue Emile-Argand 11, 2000 Neuchâtel, Switzerland
| | - Jacob C Koella
- Institute of Biology, University of Neuchâtel, Rue Emile-Argand 11, 2000 Neuchâtel, Switzerland
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The ability of Anopheles gambiae mosquitoes to bite through a permethrin-treated net and the consequences for their fitness. Sci Rep 2019; 9:8141. [PMID: 31148587 PMCID: PMC6544760 DOI: 10.1038/s41598-019-44679-1] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2018] [Accepted: 05/22/2019] [Indexed: 11/08/2022] Open
Abstract
Insecticide-treated bed-nets (ITNs) control malaria by keeping mosquitoes from reaching people sleeping under a net and by killing mosquitoes. Most tests of ITNs consider their overall epidemiological outcome without considering the different behaviors underlying their effects. Here we consider one of these behaviors: that mosquitoes can bite through the net if its user is touching it. We assayed the ability of an insecticide-sensitive strain of the mosquito Anopheles gambiae to bite through a permethrin-treated or an untreated net, and their subsequent survival and fecundity. Despite the irritancy of permethrin, 71% of the mosquitoes took blood through the ITN (vs. 99% through the untreated net). The ITN reduced the time spent biting, the blood-meal size and the fecundity, and it killed about 15% of the mosquitoes within 24 hours of feeding (vs. 5% on the untreated net). However, the mosquito's survival was much higher than what we found in WHO cone assays, suggesting that the bloodmeal increased the mosquito's resistance to the insecticide. Thus, our results suggest that the irritancy and the toxicity of ITNs are reduced when mosquitoes contact and feed on their host, which will affect our understanding of the personal and community protection offered by the ITNs.
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Saeed Q, Ahmad F, Iqbal N, Zaka SM. Chemical control of polyphagous pests on their auxiliary hosts can minimize insecticide resistance: A case study of Spodoptera exigua Hübner (Lepidoptera: Noctuidae) in cotton agroecosystem. ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY 2019; 171:721-727. [PMID: 30658308 DOI: 10.1016/j.ecoenv.2019.01.038] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/01/2018] [Revised: 11/27/2018] [Accepted: 01/09/2019] [Indexed: 06/09/2023]
Abstract
Use of insecticides for agricultural pest management have significant environmental impacts. Using integrated approaches to minimize the frequency of insecticide application by incorporating cultural control tactics can keep environmental hazards to the minimum. The alternate hosts of polyphagous pests have significant role in population development and success of chemical control. Spodoptera exigua Hübner is a polyphagous insect pest of frequently cultivated crops (castor, cauliflower, okra and spinach) in cotton agroecosystem of Pakistan. Since the timeline of cultivation of these crops coincide and the field are often adjoining, S. exigua therefore keeps on migrating from one crop to the other both in winter and summer. Such shifting has a significant effect on the susceptibility of the larvae against the commonly used insecticides. To reveal these effects, toxicity of chlorpyrifos and cypermethrin were tested against the larvae fed on their natal hosts, then shifted to their auxiliary hosts and finally upon their reversal to the natal host. Results have demonstrated that resistance of S. exigua decreased significantly when the populations are cultured on a single host in the laboratory. Field population collected from castor crop demonstrated the highest decrease in resistance ratios against chlorpyrifos and cypermethrin (i.e., 210- and 403-folds, respectively) compared to its field population. Moreover, alternation of generations among cotton and alternate crops, in general, decreased the resistance against chlorpyrifos and cypermethrin. But when these populations return to cotton again, their resistance has been found to be increased significantly. A similar but more obvious change in resistance ratio is observed when the pest population from cotton hosts is fed on spinach (a host available in the later developmental stages of cotton) and vice versa upon their return to cotton. Hence it is suggested that for effective management of S. exigua a continual routine of pest control on available alternate hosts, especially castor and spinach should be administered at critical stages of cotton crop development, i.e. early seedling stage and the late fruiting stage.
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Affiliation(s)
- Qamar Saeed
- Plant Protection Research Institute, Guangdong Academy of Agricultural Sciences, Tianhe District, Guangzhou, Guangdong 510640, China; Department of Entomology, Faculty of Agricultural Sciences and Technology, Bahauddin Zakariya University, Multan, Pakistan.
| | - Faheem Ahmad
- Department of Biosciences, COMSATS University Islamabad (CUI), Park Road, Chak Shehzad, Islamabad (ICT), Pakistan.
| | - Naeem Iqbal
- Department of Plant Protection, Faculty of Agricultural Sciences, Ghazi University, Dera, Ghazi Khan, Pakistan; Department of Entomology, Faculty of Agriculture and Environmental Sciences, Muhammad Nawaz Shareef University of Agriculture, Multan 60000, Pakistan
| | - Syed Muhammad Zaka
- Department of Entomology, Faculty of Agricultural Sciences and Technology, Bahauddin Zakariya University, Multan, Pakistan
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Souza RS, Virginio F, Riback TIS, Suesdek L, Barufi JB, Genta FA. Microorganism-Based Larval Diets Affect Mosquito Development, Size and Nutritional Reserves in the Yellow Fever Mosquito Aedes aegypti (Diptera: Culicidae). Front Physiol 2019; 10:152. [PMID: 31024326 PMCID: PMC6465640 DOI: 10.3389/fphys.2019.00152] [Citation(s) in RCA: 53] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2018] [Accepted: 02/08/2019] [Indexed: 12/11/2022] Open
Abstract
Background Mosquito larvae feed on organic detritus from the environment, particularly microorganisms comprising bacteria, protozoa, and algae as well as crustaceans, plant debris, and insect exuviae. Little attention has been paid to nutritional studies in Aedes aegypti larvae. Objectives We investigated the effects of yeast, bacteria and microalgae diets on larval development, pupation time, adult size, emergence, survivorship, lifespan, and wing morphology. Materials and Methods Microorganisms (or Tetramin® as control) were offered as the only source of food to recently hatched first instar larvae and their development was followed until the adult stage. Protein, carbohydrate, glycogen, and lipid were analyzed in single larvae to correlate energetic reserve accumulation by larva with the developmental rates and nutritional content observed. FITC-labeled microorganisms were offered to fourth instar larvae, and its ingestion was recorded by fluorescence microscopy and quantitation. Results and Discussion Immature stages developed in all diets, however, larvae fed with bacteria and microalgae showed a severe delay in development rates, pupation time, adult emergence and low survivorship. Adult males emerged earlier as expected and had longer survival than females. Diets with better nutritional quality resulted in adults with bigger wings. Asaia sp. and Escherichia coli resulted in better nutrition and developmental parameters and seemed to be the best bacterial candidates to future studies using symbiont-based control. The diet quality was measured and presented different protein and carbohydrate amounts. Bacteria had the lowest protein and carbohydrate rates, yeasts had the highest carbohydrate amount and microalgae showed the highest protein content. Larvae fed with microalgae seem not to be able to process and store these diets properly. Larvae were shown to be able to process yeast cells and store their energetic components efficiently. Conclusion Together, our results point that Ae. aegypti larvae show high plasticity to feed, being able to develop under different microorganism-based diets. The important role of Ae. aegypti in the spread of infectious diseases requires further biological studies in order to understand the vector physiology and thus to manage the larval natural breeding sites aiming a better mosquito control.
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Affiliation(s)
- Raquel Santos Souza
- Laboratório de Bioquímica e Fisiologia de Insetos, Instituto Oswaldo Cruz, FIOCRUZ, Rio de Janeiro, Brazil
| | - Flavia Virginio
- Laboratório Especial de Coleções Zoológicas, Instituto Butantan, São Paulo, Brazil
| | | | - Lincoln Suesdek
- Laboratório de Parasitologia, Instituto Butantan, São Paulo, Brazil
- Instituto de Medicina Tropical de São Paulo, Universidade de São Paulo, São Paulo, Brazil
| | - José Bonomi Barufi
- Laboratório de Ficologia, Departamento de Botânica, Centro de Ciências Biológicas, Universidade Federal de Santa Catarina, Florianópolis, Brazil
| | - Fernando Ariel Genta
- Laboratório de Bioquímica e Fisiologia de Insetos, Instituto Oswaldo Cruz, FIOCRUZ, Rio de Janeiro, Brazil
- Instituto Nacional de Ciência e Tecnologia em Entomologia Molecular, Rio de Janeiro, Brazil
- *Correspondence: Fernando Ariel Genta, ;
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Thiévent K, Hauser G, Elaian O, Koella JC. The interaction between permethrin exposure and malaria infection affects the host-seeking behaviour of mosquitoes. Malar J 2019; 18:79. [PMID: 30871559 PMCID: PMC6416862 DOI: 10.1186/s12936-019-2718-x] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2018] [Accepted: 03/11/2019] [Indexed: 01/13/2023] Open
Abstract
Background Insecticide-treated bed nets (ITNs) help to control malaria by mechanically impeding the biting of mosquitoes, by repelling and irritating them and by killing them. In contrast to spatial repellency, irritancy implies that mosquitoes contact the ITN and are exposed to at least a sub-lethal dose of insecticide, which impedes their further blood-seeking. This would weaken the transmission of malaria, if mosquitoes are infectious. Methods It was therefore tested whether sub-lethal exposure to permethrin impedes blood-feeding differently in uninfected mosquitoes and in mosquitoes carrying the non-transmissible stage (oocysts) or the infectious stage (sporozoites) of the malaria parasite Plasmodium berghei. In addition, as the degree of irritancy determines the dose of insecticide the mosquitoes may receive, the irritancy to permethrin of infected and uninfected mosquitoes was compared. Results In this laboratory setting, sub-lethal exposure to permethrin inhibited the blood-seeking behaviour of Anopheles gambiae mosquitoes for almost 48 h. Although infection by malaria did not affect the irritancy of the mosquitoes to permethrin at either the developmental stage or the infectious stage, both stages of infection shortened the duration of inhibition of blood-seeking. Conclusions The results suggest that the impact of ITNs may be weaker for malaria-infected than for uninfected mosquitoes. This will help to understand the global impact of ITNs on the transmission of malaria and gives a more complete picture of the effectiveness of that vector control measure. Electronic supplementary material The online version of this article (10.1186/s12936-019-2718-x) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Kevin Thiévent
- Institute of Biology, University of Neuchâtel, Rue Emile-Argand 11, 2000, Neuchâtel, Switzerland.
| | - Gaël Hauser
- Institute of Biology, University of Neuchâtel, Rue Emile-Argand 11, 2000, Neuchâtel, Switzerland
| | - Obada Elaian
- Institute of Biology, University of Neuchâtel, Rue Emile-Argand 11, 2000, Neuchâtel, Switzerland
| | - Jacob C Koella
- Institute of Biology, University of Neuchâtel, Rue Emile-Argand 11, 2000, Neuchâtel, Switzerland
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Spielmeyer A, Schetelig MF, Etang J. High-throughput analysis of insecticides on malaria vectors using liquid chromatography tandem mass spectrometry. PLoS One 2019; 14:e0211064. [PMID: 30730918 PMCID: PMC6366735 DOI: 10.1371/journal.pone.0211064] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2018] [Accepted: 12/21/2018] [Indexed: 11/18/2022] Open
Abstract
BACKGROUND Different setups and protocols have been developed for investigating insecticide effects on Anopheles (An.) mosquitoes, vectors of malaria. However, chemical uptake resulting from their tarsal contact with insecticide-treated material has seldom been investigated. To address the challenges encountered in the interpretation of bioassay data, a high throughput method for chemical analysis on malaria vectors was developed and validated for five selected insecticides including alpha-cypermethrin (aCYP), deltamethrin (DM), etofenprox (EPX), permethrin (PM), pirimiphos-methyl (PPM). METHODS The method includes a single chemical extraction step via an ultrasound probe on mosquito samples and analysis via liquid chromatography coupled to high-resolution tandem mass spectrometry (UHPLC-MS/MS). The protocol was established for two malaria vector species, Anopheles gambiae senso stricto (s.s.) and An. stephensi, both males and females. Recovery rates ranged from 70 to 100% without any influence of sex or species. The method was efficiently applied to female An. gambiae s.s. of the KISUMU1 reference strain, after susceptibility tests using the World Health Organization's standard protocol. RESULTS Susceptibility tests revealed 13.4-18.4 minutes knockdown times for 50% mosquitoes during exposure to EPX and pyrethroids. The mortality rates 24 hours post-exposure to insecticides were mostly 99-100%, except in two PM and three PPM assays suggesting possible or confirmed resistance to these insecticides. The mean insecticide uptake in dead mosquitoes ranged from 23 pg (aCYP) to 1812 pg (EPX) per specimen. However, the mean uptake in survivors to PM and PPM was reduced by at least 25%, suggesting that acute doses were not achieved in these specimens during bioassays. CONCLUSIONS The developed and validated UHPLC-MS/MS method could be used to address some limitations of bioassays or to assess the penetration of insecticides in mosquito matrix with reference to cuticle thickness and other insecticide resistance mechanisms.
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Affiliation(s)
- Astrid Spielmeyer
- Justus Liebig University Giessen, Institute for Food Chemistry and Food Biotechnology, Giessen, Germany
| | - Marc F. Schetelig
- Justus Liebig University Giessen, Institute for Insect Biotechnology, Giessen, Germany
| | - Josiane Etang
- Justus Liebig University Giessen, Institute for Insect Biotechnology, Giessen, Germany
- Organisation de Coordination pour la lutte contre les Endémies en Afrique Centrale (OCEAC), Institut de Recherche de Yaoundé (IRY), Yaoundé, Cameroun
- University of Douala, Faculty of Medicine and Pharmaceutical Sciences, Douala, Cameroon
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Kristan M, Abeku TA, Lines J. Effect of environmental variables and kdr resistance genotype on survival probability and infection rates in Anopheles gambiae (s.s.). Parasit Vectors 2018; 11:560. [PMID: 30367663 PMCID: PMC6204000 DOI: 10.1186/s13071-018-3150-8] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2018] [Accepted: 10/14/2018] [Indexed: 01/16/2023] Open
Abstract
BACKGROUND Environmental factors, especially ambient temperature and relative humidity affect both mosquitoes and malaria parasites. The early part of sporogony is most sensitive and is affected by high temperatures and temperature fluctuation immediately following ingestion of an infectious blood meal. The aim of this study was to explore whether environmental variables such as temperature, together with the presence of the kdr insecticide resistance mutations, have an impact on survival probability and infection rates in wild Anopheles gambiae (s.s.) exposed and unexposed to a pyrethroid insecticide. METHODS Anopheles gambiae (s.s.) were collected as larvae, reared to adults, and fed on blood samples from 42 Plasmodium falciparum-infected local patients at a health facility in mid-western Uganda, then exposed either to nets treated with sub-lethal doses of deltamethrin or to untreated nets. After seven days, surviving mosquitoes were dissected and their midguts examined for oocysts. Prevalence (proportion infected) and intensity of infection (number of oocysts per infected mosquito) were recorded for each group. Mosquito mortality was recorded daily. Temperature and humidity were recorded every 30 minutes throughout the experiments. RESULTS Our findings indicate that apart from the effect of deltamethrin exposure, mean daily temperature during the incubation period, temperature range during the first 24 hours and on day 4 post-infectious feed had a highly significant effect on the risk of infection. Deltamethrin exposure still significantly impaired survival of kdr homozygous mosquitoes, while mean daily temperature and relative humidity during the incubation period independently affected mosquito mortality. Significant differences in survival of resistant genotypes were detected, with the lowest survival recorded in mosquitoes with heterozygote L1014S/L1014F genotype. CONCLUSIONS This study confirmed that the early part of sporogony is most affected by temperature fluctuations, while environmental factors affect mosquito survival. The impact of insecticide resistance on malaria infection and vector survival needs to be assessed separately for mosquitoes with different resistance mechanisms to fully understand its implications for currently available vector control tools and malaria transmission.
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Affiliation(s)
- Mojca Kristan
- Department of Disease Control, London School of Hygiene & Tropical Medicine, London, UK.
| | | | - Jo Lines
- Department of Disease Control, London School of Hygiene & Tropical Medicine, London, UK
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Mulatier M, Porciani A, Nadalin L, Ahoua Alou LP, Chandre F, Pennetier C, Dormont L, Cohuet A. DEET Efficacy Increases With Age in the Vector Mosquitoes Anopheles gambiae s.s. and Aedes albopictus (Diptera: Culicidae). JOURNAL OF MEDICAL ENTOMOLOGY 2018; 55:1542-1548. [PMID: 30137424 PMCID: PMC6201824 DOI: 10.1093/jme/tjy134] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/09/2018] [Indexed: 05/04/2023]
Abstract
Old mosquitoes are the most likely to transmit pathogens due to the higher probability that they will be exposed to pathogens, and the time required before a mosquito becomes infectious, the extrinsic incubation period (EIP). However, old mosquitoes are rarely considered in the evaluation of control tools. This study evaluated the effect of mosquito aging on the repellent efficacy of N,N-diethyl-3-methylbenzamide (DEET) in two vector mosquitoes, Anopheles gambiae s.s. (Giles) (Diptera: Culicidae) and Aedes albopictus (Skuse) (Diptera: Culicidae), respective vectors of malaria parasites and arboviruses such as dengue, chikungunya, and Zika viruses. For both mosquito species, DEET-induced inhibition of blood-feeding was assessed in three age classes. Life-history traits related to mosquito fecundity and survival following DEET exposure were also measured. Results showed that, in both species, bloodmeal inhibition induced by DEET was significantly higher in old females (>18 d old) than in younger ones (<13 d old). Life history traits recording showed no combined effects of DEET and aging on mosquito blood engorgement, oviposition rate, number of eggs laid nor survival; however, age effects are reported for all these traits. These results highlight the need for taking into account mosquito age in the evaluation of integrated mosquito management tools. They also suggest that the control of vector-borne pathogens with a long EIP could be improved by targeting old mosquitoes and supports the efficacy of repellents in the fight against mosquito-borne diseases.
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Affiliation(s)
- Margaux Mulatier
- MIVEGEC, IRD, CNRS, Univ. Montpellier, BP, Montpellier Cedex, France
- CEFE, Univ. Paul Valéry Montpellier, CNRS, Univ. Montpellier, EPHE, IRD, Montpellier, France
| | | | - Louis Nadalin
- MIVEGEC, IRD, CNRS, Univ. Montpellier, BP, Montpellier Cedex, France
| | | | - Fabrice Chandre
- MIVEGEC, IRD, CNRS, Univ. Montpellier, BP, Montpellier Cedex, France
| | - Cédric Pennetier
- MIVEGEC, IRD, CNRS, Univ. Montpellier, BP, Montpellier Cedex, France
- Institut Pierre Richet, Bouaké, Côte d’Ivoire
| | - Laurent Dormont
- CEFE, Univ. Paul Valéry Montpellier, CNRS, Univ. Montpellier, EPHE, IRD, Montpellier, France
| | - Anna Cohuet
- MIVEGEC, IRD, CNRS, Univ. Montpellier, BP, Montpellier Cedex, France
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Barreaux AMG, Stone CM, Barreaux P, Koella JC. The relationship between size and longevity of the malaria vector Anopheles gambiae (s.s.) depends on the larval environment. Parasit Vectors 2018; 11:485. [PMID: 30157916 PMCID: PMC6114828 DOI: 10.1186/s13071-018-3058-3] [Citation(s) in RCA: 42] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2018] [Accepted: 08/10/2018] [Indexed: 12/23/2022] Open
Abstract
Background Understanding the variation in vector-borne disease transmission intensity across time and space relies on a thorough understanding of the impact of environmental factors on vectorial capacity traits of mosquito populations. This is driven primarily by variation in larval development and growth, with carryover effects influencing adult traits such as longevity and adult body size. The relationship between body size and longevity strongly affects the evolution of life histories and the epidemiology of vector-borne diseases. This relationship ranges from positive to negative but the reasons for this variability are not clear. Both traits depend on a number of environmental factors, but primarily on temperature as well as availability of nutritional resources. We therefore asked how the larval environment of the mosquito Anopheles gambiae Giles (sensu stricto) (Diptera: Culicidae) affects the relationship between body size and longevity. Methods We reared the larvae of An. gambiae individually at three temperatures (21, 25 and 29 °C) and two food levels (the standard and 50% of our laboratory diet) and measured adult size and longevity. We estimated the direct and indirect (via adult size) effects of food and temperature on longevity with a piecewise structural equation model (SEM). Results We confirmed the direct effects of food and temperature during larval development on body size, as wing length decreased with increasing temperature and decreasing food levels. While the overall relationship between size and longevity was weak, we measured striking differences among environments. At 25 °C there was no clear relationship between size and longevity; at 29 °C the association was negative with standard food but positive with low food; whereas at 21 °C it was positive with standard food but negative with low food. Conclusions The larval environment influences the adult’s fitness in complex ways with larger mosquitoes living longer in some environments but not in others. This confirmed our hypothesis that the relationship between size and longevity is not limited to a positive correlation. A better understanding of this relationship and its mechanisms may improve the modelling of the transmission of vector borne diseases, the evolution of life history traits, and the influence of vector control. Electronic supplementary material The online version of this article (10.1186/s13071-018-3058-3) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Antoine M G Barreaux
- Center for Infectious Disease Dynamics and Department of Entomology, Pennsylvania State University, University Park, PA, 16802, USA. .,Laboratory of Ecology and Epidemiology of Parasites, Institute of Biology, University of Neuchâtel, Rue Emile-Argand 11, 2000, Neuchâtel, Switzerland.
| | - Chris M Stone
- Illinois Natural History Survey, University of Illinois, Champaign, IL, 61820, USA
| | - Priscille Barreaux
- Center for Infectious Disease Dynamics and Department of Entomology, Pennsylvania State University, University Park, PA, 16802, USA.,Laboratory of Ecology and Epidemiology of Parasites, Institute of Biology, University of Neuchâtel, Rue Emile-Argand 11, 2000, Neuchâtel, Switzerland
| | - Jacob C Koella
- Laboratory of Ecology and Epidemiology of Parasites, Institute of Biology, University of Neuchâtel, Rue Emile-Argand 11, 2000, Neuchâtel, Switzerland
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27
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Thiévent K, Hofer L, Rapp E, Tambwe MM, Moore S, Koella JC. Malaria infection in mosquitoes decreases the personal protection offered by permethrin-treated bednets. Parasit Vectors 2018; 11:284. [PMID: 29728155 PMCID: PMC5936035 DOI: 10.1186/s13071-018-2846-0] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2017] [Accepted: 04/12/2018] [Indexed: 12/19/2022] Open
Abstract
Background Insecticides targeting adult mosquitoes are the main way of controlling malaria. They work not only by killing mosquitoes, but also by repelling and irritating them. Indeed their repellent action gives valuable personal protection against biting mosquitoes. In the context of malaria control this personal protection is especially relevant when mosquitoes are infectious, whereas to protect the community we would prefer that the mosquitoes that are not yet infectious are killed (so, not repelled) by the insecticide. As the infectious stage of malaria parasites increases the motivation of mosquitoes to bite, we predicted that it would also change their behavioural response to insecticides. Results With two systems, a laboratory isolate of the rodent malaria Plasmodium berghei infecting Anopheles gambiae and several isolates of P. falciparum obtained from schoolchildren in Tanzania that infected Anopheles arabiensis, we found that mosquitoes harbouring the infectious stage (the sporozoites) of the parasite were less repelled by permethrin-treated nets than uninfected ones. Conclusions Our results suggest that, at least in the laboratory, malaria infection decreases the personal protection offered by insecticide-treated nets at the stage where the personal protection is most valuable. Further studies must investigate whether these results hold true in the field and whether the less effective personal protection can be balanced by increased community protection. Electronic supplementary material The online version of this article (10.1186/s13071-018-2846-0) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Kevin Thiévent
- Institute of Biology, University of Neuchâtel, Rue Emile-Argand 11, 2000, Neuchâtel, Switzerland.
| | - Lorenz Hofer
- Institute of Biology, University of Neuchâtel, Rue Emile-Argand 11, 2000, Neuchâtel, Switzerland
| | - Elise Rapp
- Institute of Biology, University of Neuchâtel, Rue Emile-Argand 11, 2000, Neuchâtel, Switzerland
| | - Mgeni Mohamed Tambwe
- Ifakara Health Institute, Intervention and Environmental Health and Ecological Sciences, P.O. Box 74, Bagamoyo, Tanzania
| | - Sarah Moore
- Ifakara Health Institute, Intervention and Environmental Health and Ecological Sciences, P.O. Box 74, Bagamoyo, Tanzania.,Swiss Tropical & Public Health Institute, Socinstrasse 57, 4002, Basel, Switzerland
| | - Jacob C Koella
- Institute of Biology, University of Neuchâtel, Rue Emile-Argand 11, 2000, Neuchâtel, Switzerland
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Huijben S, Paaijmans KP. Putting evolution in elimination: Winning our ongoing battle with evolving malaria mosquitoes and parasites. Evol Appl 2018; 11:415-430. [PMID: 29636796 PMCID: PMC5891050 DOI: 10.1111/eva.12530] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2017] [Accepted: 08/01/2017] [Indexed: 12/17/2022] Open
Abstract
Since 2000, the world has made significant progress in reducing malaria morbidity and mortality, and several countries in Africa, South America and South-East Asia are working hard to eliminate the disease. These elimination efforts continue to rely heavily on antimalarial drugs and insecticide-based interventions, which remain the cornerstones of malaria treatment and prevention. However, resistance has emerged against nearly every antimalarial drug and insecticide that is available. In this review we discuss the evolutionary consequences of the way we currently implement antimalarial interventions, which is leading to resistance and may ultimately lead to control failure, but also how evolutionary principles can be applied to extend the lifespan of current and novel interventions. A greater understanding of the general evolutionary principles that are at the core of emerging resistance is urgently needed if we are to develop improved resistance management strategies with the ultimate goal to achieve a malaria-free world.
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Affiliation(s)
- Silvie Huijben
- ISGlobalBarcelona Ctr. Int. Health Res. (CRESIB)Hospital Clínic ‐ Universitat de BarcelonaBarcelonaSpain
| | - Krijn P. Paaijmans
- ISGlobalBarcelona Ctr. Int. Health Res. (CRESIB)Hospital Clínic ‐ Universitat de BarcelonaBarcelonaSpain
- Centro de Investigação em Saúde de ManhiçaMaputoMozambique
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Ong SQ, Jaal Z. Larval Age and Nutrition Affect the Susceptibility of Culex quinquefasciatus (Diptera: Culicidae) to Temephos. JOURNAL OF INSECT SCIENCE (ONLINE) 2018; 18:4962179. [PMID: 29718500 PMCID: PMC5887730 DOI: 10.1093/jisesa/iey032] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Larval age and nutrition significantly affected the insect's physiology. These influences are important when rearing a population of vectors that is used to monitor the resistance level, in which standardized conditions are crucial for a more harmonized result. Little information has been reported on the effects of larval age and nutrition on the susceptibility of insects to insecticides, and therefore, we studied the effects on the susceptibility of Culex quinquefasciatus Say's (Diptera: Culicidae) larvae to temephos by comparing the median lethal concentration (LC50) after 24 hr between the second and fourth instar larvae and between the larvae that fed on protein-based and carbohydrate-based larval diets. The susceptibility of the larvae was significantly affected by the larval diets, as the larvae that fed on protein-based beef food and milk food demonstrated significantly higher LC50 value compared with the larvae that fed on carbohydrate-based food: lab food and yeast food. The larval diet interacted significantly with the larval age: while the second instar larvae were susceptible to temephos when supplied with carbohydrate-based food, the second and fourth instar larvae had no significant effect when supplied with protein-based diets, implying that a protein-rich environment may cause the mosquito to be less susceptible to temephos. This study suggested the importance of standardizing nutrition when rearing a vector population in order to obtain more harmonized dosage-response results in an insecticide resistance monitoring program. Future research could focus on the biochemical mechanism between the nutrition and the enzymatic activities of the vector.
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Affiliation(s)
- Song-Quan Ong
- Vector Control Research Unit, School of Biological Sciences, Universiti Sains Malaysia, Penang, Malaysia
- KDU Penang University College, Jalan Anson, Georgetown, Penang, Malaysia
| | - Zairi Jaal
- Vector Control Research Unit, School of Biological Sciences, Universiti Sains Malaysia, Penang, Malaysia
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30
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Aldridge RL, Kaufman PE, Bloomquist JR, Gezan SA, Linthicum KJ. Application Site and Mosquito Age Influences Malathion- and Permethrin-Induced Mortality in Culex quinquefasciatus (Diptera: Culicidae). JOURNAL OF MEDICAL ENTOMOLOGY 2017; 54:1692-1698. [PMID: 28968685 DOI: 10.1093/jme/tjx160] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/24/2017] [Indexed: 06/07/2023]
Abstract
Concentrations of malathion and permethrin typical in droplets generated from ultra-low-volume and low-volume applications used to control mosquito populations were evaluated for efficacy against multiple-aged Culex quinquefasciatus Say (Diptera: Culicidae), using a topical bioassay. Although insecticide droplets will impinge on many exoskeletal body regions and a range of ages of mosquitoes in a population, traditional mosquito topical bioassays focus pesticide application to the mesothoracic pleural or dorsal regions across an average mosquito age (e.g., 3-7 d). Our results document nonuniform insecticide sensitivity across body regions at ages not previously assessed in mosquitoes (teneral and 14-d old). We expect our findings to influence the topical bioassay process, illustrating the difference in mosquito body regions and ages that ultimately may explain insecticide effectiveness wherever droplets impinge upon the mosquito body during field control applications.
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Affiliation(s)
- Robert L Aldridge
- United States Department of Agriculture, Agricultural Research Service, Center for Medical, Agricultural, and Veterinary Entomology, 1600 SW 23rd Dr., Gainesville, FL 32608
| | - Phillip E Kaufman
- Entomology and Nematology Department, P.O. Box 110620, University of Florida, Gainesville, FL 32611
| | - Jeffrey R Bloomquist
- Entomology and Nematology Department, Emerging Pathogens Institute, P.O. Box 100009, University of Florida, Gainesville, FL 32611
| | - Salvador A Gezan
- School of Forest Resources and Conservation, P.O. Box 110410, University of Florida, Gainesville, FL 32611
| | - Kenneth J Linthicum
- United States Department of Agriculture, Agricultural Research Service, Center for Medical, Agricultural, and Veterinary Entomology, 1600 SW 23rd Dr., Gainesville, FL 32608
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Abstract
Resistance to first-line treatments for Plasmodium falciparum malaria and the insecticides used for Anopheles vector control are threatening malaria elimination efforts. Suboptimal responses to drugs and insecticides are both spreading geographically and emerging independently and are being seen at increasing intensities. Whilst resistance is unavoidable, its effects can be mitigated through resistance management practices, such as exposing the parasite or vector to more than one selective agent. Resistance contributed to the failure of the 20th century Global Malaria Eradication Programme, and yet the global response to this issue continues to be slow and poorly coordinated-too often, too little, too late. The Malaria Eradication Research Agenda (malERA) Refresh process convened a panel on resistance of both insecticides and antimalarial drugs. This paper outlines developments in the field over the past 5 years, highlights gaps in knowledge, and proposes a research agenda focused on managing resistance. A deeper understanding of the complex biological processes involved and how resistance is selected is needed, together with evidence of its public health impact. Resistance management will require improved use of entomological and parasitological data in decision making, and optimisation of the useful life of new and existing products through careful implementation, combination, and evaluation. A proactive, collaborative approach is needed from basic science and the development of new tools to programme and policy interventions that will ensure that the armamentarium of drugs and insecticides is sufficient to deal with the challenges of malaria control and its elimination.
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32
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Alout H, Roche B, Dabiré RK, Cohuet A. Consequences of insecticide resistance on malaria transmission. PLoS Pathog 2017; 13:e1006499. [PMID: 28880906 PMCID: PMC5589250 DOI: 10.1371/journal.ppat.1006499] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Affiliation(s)
- Haoues Alout
- Institut des Sciences de l’Evolution de Montpellier, CNRS, IRD, University of Montpellier, Montpellier, France
| | - Benjamin Roche
- Institut de recherche pour le développement (IRD), Maladies Infectieuses et Vecteurs, Ecologie, Génétique, Evolution et Contrôle (MIVEGEC), Montpellier, France
- UMI IRD/UPMC 209, Unité de Modélisation Mathématique et Informatique des Sytèmes Complexes (UMMISCO lab), Bondy, France
| | - Roch Kounbobr Dabiré
- Institut de Recherche en Sciences de la Santé (IRSS), Bobo-Dioulasso, Burkina Faso
| | - Anna Cohuet
- Institut de recherche pour le développement (IRD), Maladies Infectieuses et Vecteurs, Ecologie, Génétique, Evolution et Contrôle (MIVEGEC), Montpellier, France
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33
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Owusu HF, Chitnis N, Müller P. Insecticide susceptibility of Anopheles mosquitoes changes in response to variations in the larval environment. Sci Rep 2017. [PMID: 28623302 PMCID: PMC5473885 DOI: 10.1038/s41598-017-03918-z] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
Insecticide resistance threatens the success achieved through vector control in reducing the burden of malaria. An understanding of insecticide resistance mechanisms would help to develop novel tools and strategies to restore the efficacy of insecticides. Although we have substantially improved our understanding of the genetic basis of insecticide resistance over the last decade, we still know little of how environmental variations influence the mosquito phenotype. Here, we measured how variations in larval rearing conditions change the insecticide susceptibility phenotype of adult Anopheles mosquitoes. Anopheles gambiae and A. stephensi larvae were bred under different combinations of temperature, population density and nutrition, and the emerging adults were exposed to permethrin. Mosquitoes bred under different conditions showed considerable changes in mortality rates and body weight, with nutrition being the major factor. Weight is a strong predictor of insecticide susceptibility and bigger mosquitoes are more likely to survive insecticide treatment. The changes can be substantial, such that the same mosquito colony may be considered fully susceptible or highly resistant when judged by World Health Organization discriminatory concentrations. The results shown here emphasise the importance of the environmental background in developing insecticide resistance phenotypes, and caution for the interpretation of data generated by insecticide susceptibility assays.
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Affiliation(s)
- Henry F Owusu
- Epidemiology and Public Health Department, Swiss Tropical and Public Health Institute, Socinstrasse 57, PO Box, CH-4002, Basel, Switzerland.,University of Basel, Petersplatz 1, CH-2003, Basel, Switzerland.,Department of Immunology and Infectious Diseases, Harvard T.H. Chan School of Public Health, 665 Huntington Ave, Boston, MA, 02115, USA
| | - Nakul Chitnis
- Epidemiology and Public Health Department, Swiss Tropical and Public Health Institute, Socinstrasse 57, PO Box, CH-4002, Basel, Switzerland.,University of Basel, Petersplatz 1, CH-2003, Basel, Switzerland
| | - Pie Müller
- Epidemiology and Public Health Department, Swiss Tropical and Public Health Institute, Socinstrasse 57, PO Box, CH-4002, Basel, Switzerland. .,University of Basel, Petersplatz 1, CH-2003, Basel, Switzerland.
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Alout H, Labbé P, Chandre F, Cohuet A. Malaria Vector Control Still Matters despite Insecticide Resistance. Trends Parasitol 2017; 33:610-618. [PMID: 28499699 DOI: 10.1016/j.pt.2017.04.006] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2017] [Revised: 04/14/2017] [Accepted: 04/18/2017] [Indexed: 11/26/2022]
Abstract
Mosquito vectors' resistance to insecticides is usually considered a major threat to the recent progresses in malaria control. However, studies measuring the impact of interventions and insecticide resistance reveal inconsistencies when using entomological versus epidemiological indices. First, evaluation tests that do not reflect the susceptibility of mosquitoes when they are infectious may underestimate insecticide efficacy. Moreover, interactions between insecticide resistance and vectorial capacity reveal nonintuitive outcomes of interventions. Therefore, considering ecological interactions between vector, parasite, and environment highlights that the impact of insecticide resistance on the malaria burden is not straightforward and we suggest that vector control still matters despite insecticide resistance.
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Affiliation(s)
- Haoues Alout
- Institut des Sciences de l'Evolution de Montpellier, CNRS, IRD, University of Montpellier, ISEM - UMR 5554, Montpellier, France.
| | - Pierrick Labbé
- Institut des Sciences de l'Evolution de Montpellier, CNRS, IRD, University of Montpellier, ISEM - UMR 5554, Montpellier, France
| | - Fabrice Chandre
- Institut de recherche pour le développement (IRD), Maladies Infectieuses et Vecteurs, Ecologie, Génétique, Evolution et Contrôle (MIVEGEC), UM-CNRS 5290 IRD 224, Montpellier, France
| | - Anna Cohuet
- Institut de recherche pour le développement (IRD), Maladies Infectieuses et Vecteurs, Ecologie, Génétique, Evolution et Contrôle (MIVEGEC), UM-CNRS 5290 IRD 224, Montpellier, France.
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35
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Campbell BE, Miller DM. A Method for Evaluating Insecticide Efficacy against Bed Bug, Cimex lectularius, Eggs and First Instars. J Vis Exp 2017. [PMID: 28362364 DOI: 10.3791/55092] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022] Open
Abstract
Standard toxicity evaluations of insecticides against insect pests are primarily conducted on adult insects. Evaluations are based on a dose-response or concentration-response curve, where mortality increases as the dose or concentration of an insecticide is increased. Standard lethal concentration (LC50) and lethal dose (LD50) tests that result in 50% mortality of a test population can be challenging for evaluating toxicity of insecticides against non-adult insect life stages, such as eggs and early instar or nymphal stages. However, this information is essential for understanding insecticide efficacy in all bed bug life stages, which affects control and treatment efforts. This protocol uses a standard dipping bioassay modified for bed bug eggs and a contact insecticidal assay for treating nymphal first instars. These assays produce a concentration-response curve to further quantify LC50 values for insecticide evaluations.
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36
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Khan GZ, Khan I, Khan IA, Alamzeb, Salman M, Ullah K. Evaluation of different formulations of IGRs against Aedes albopictus and Culex quinquefasciatus (Diptera: Culicidae). Asian Pac J Trop Biomed 2016. [DOI: 10.1016/j.apjtb.2016.04.008] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
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37
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Barreaux AMG, Barreaux P, Koella JC. Overloading the immunity of the mosquito Anopheles gambiae with multiple immune challenges. Parasit Vectors 2016; 9:210. [PMID: 27080035 PMCID: PMC4832557 DOI: 10.1186/s13071-016-1491-8] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2016] [Accepted: 04/03/2016] [Indexed: 11/14/2022] Open
Abstract
Background Melanisation – the production and deposition of a layer of melanin that encapsulates many pathogens, including bacteria, filarial nematodes and malaria parasites is one of the main immune responses in mosquitoes. Can a high parasite load overload this immune response? If so, how is the melanisation response distributed among the individual parasites? Methods We considered these questions with the mosquito Anopheles gambiae by inoculating individuals simultaneously with one, two or three negatively charged Sephadex beads, and estimating the melanisation as the darkness of the bead (which ranges from about 0 for unmelanised beads to 100 for the most melanised beads of our experiment). Results As the number of beads increased, the average degree to which beads were melanised decreased from 71 to 50. While the darkness of the least melanised bead in a mosquito decreased from an average of 71 to 35, the darkness of the most strongly melanised one did not change with the number of beads. Conclusions As the number of beads increased, the mosquito’s immune response became overloaded. The mosquito’s response was to prioritise the melanisation of one bead rather than distributing its response over all beads. Such immune overloading may be an important factor underlying the evolution of resistance against vector-borne diseases. Electronic supplementary material The online version of this article (doi:10.1186/s13071-016-1491-8) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- A M G Barreaux
- Laboratory of Ecology and Epidemiology of Parasites, Institute of Biology, University of Neuchâtel, Rue Emile-Argand 11, 2000, Neuchâtel, Switzerland.
| | - P Barreaux
- Laboratory of Ecology and Epidemiology of Parasites, Institute of Biology, University of Neuchâtel, Rue Emile-Argand 11, 2000, Neuchâtel, Switzerland
| | - J C Koella
- Laboratory of Ecology and Epidemiology of Parasites, Institute of Biology, University of Neuchâtel, Rue Emile-Argand 11, 2000, Neuchâtel, Switzerland
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38
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Saddler A, Koella JC. Modelling the impact of declining insecticide resistance with mosquito age on malaria transmission. MALARIAWORLD JOURNAL 2015; 6:13. [PMID: 38779631 PMCID: PMC11107876 DOI: 10.5281/zenodo.10876461] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Figures] [Subscribe] [Scholar Register] [Indexed: 05/25/2024]
Abstract
Background The evolution of insecticide resistance can lead to an increase in the entomological indicators of malaria transmission, such as mosquito survival and blood feeding rates, thus threatening efforts to control malaria. Yet, there is little evidence from the field that malaria control programmes are failing due to insecticide resistance. One explanation for this apparent contradiction is the growing evidence that insecticide resistance declines with mosquito age. Once a mosquito is first infected by Plasmodium parasites, it will not be able to transmit those parasites until they have undergone development, which lasts around 10 days. Thus, although the evolution of resistance in a population will enhance the survival of young mosquitoes, the insecticide may still kill old, and thus potentially infectious, mosquitoes, and thereby maintaining its efficacy in controlling malaria. Materials and Methods The current evidence for age-related insecticide resistance is reviewed. A mathematical model is then described that predicts how the decline of resistance with the age of a mosquito will affect the intensity of transmission of malaria. The model combines the behavioural response of the mosquitoes to insecticides with an epidemiological model of malaria. Results It was found that phenotypic resistance decreases between 1.37% to 9.71% per day, independent of the mosquito species or strain. The models suggest that a decline in resistance within this range strongly diminishes the predicted impact of insecticide resistance on the effectiveness of malaria transmission-controlling interventions. Conclusions Our model can be used to assess the threat of insecticide-resistance for the control of malaria. The model confirms observations from the field suggesting that, even where genetically insecticide-resistant mosquitoes dominate populations, insecticides can substantially reduce the transmission of malaria.
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Affiliation(s)
- Adam Saddler
- Division of Biology, Faculty of Life Sciences, Imperial College London, Silwood Park Campus, Ascot, Berkshire SL5 2PZ, United Kingdom
- Faculté des Sciences, Institut de Biologie, Université de Neuchâtel, Rue Emile-Argand 11, CH-2000 Neuchâtel, Switzerland
- Department of Epidemiology and Public Health, Swiss Tropical and Public Health Institute, Socinstrasse, 57, CH-4002 Basel, Switzerland
- University of Basel, Petersplatz 1, Basel 4003, Switzerland
| | - Jacob C Koella
- Faculté des Sciences, Institut de Biologie, Université de Neuchâtel, Rue Emile-Argand 11, CH-2000 Neuchâtel, Switzerland
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Birget PLG, Koella JC. A genetic model of the effects of insecticide-treated bed nets on the evolution of insecticide-resistance. EVOLUTION MEDICINE AND PUBLIC HEALTH 2015; 2015:205-15. [PMID: 26320183 PMCID: PMC4571732 DOI: 10.1093/emph/eov019] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/23/2013] [Accepted: 08/12/2013] [Indexed: 01/28/2023]
Abstract
BACKGROUND AND OBJECTIVES The evolution of insecticide-resistance in malaria vectors is emerging as a serious challenge for the control of malaria. Modelling the spread of insecticide-resistance is an essential tool to understand the evolutionary pressures and dynamics caused by the application of insecticides. METHODOLOGY We developed a population-genetic model of the spread of insecticide-resistance in a population of Anopheles vectors in response to insecticides used either as adulticides (focussing on insecticide-treated bed nets (ITNs)) or as larvicides (either for the control of malaria or, as an inadvertent side-product, in agriculture). RESULTS We show that indoor use of insecticides leads to considerably less selection pressure than their use as larvicides, supporting the idea that most resistance of malaria vectors is due to the agricultural use of the insecticides that are also used for malaria control. The reasons for the relatively low selection pressure posed by adulticides are (i) that males are not affected by the ITNs and, in particular, (ii) that the insecticides are also repellents, keeping mosquitoes at bay from contacting the insecticide but also driving them to bite either people who do not use the insecticide or alternative hosts. CONCLUSION We conclude by discussing the opposing public health benefits of high repellency at an epidemiological and an evolutionary timescale: whereas repellency is beneficial to delay the evolution of resistance, other models have shown that it decreases the population-level protection of the insecticide.
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Affiliation(s)
- Philip L G Birget
- Imperial College London, Life Sciences Division, Silwood Park, Ascot, England and Present address: Institute of Evolutionary Biology, University of Edinburgh, Ashworth Laboratories, Scotland
| | - Jacob C Koella
- Institute of Biology, Université de Neuchâtel, 11 rue Emile-Argand, CH-2000 Neuchâtel, Switzerland
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Saddler A, Burda PC, Koella JC. Resisting infection by Plasmodium berghei increases the sensitivity of the malaria vector Anopheles gambiae to DDT. Malar J 2015; 14:134. [PMID: 25888982 PMCID: PMC4379605 DOI: 10.1186/s12936-015-0646-y] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2015] [Accepted: 03/08/2015] [Indexed: 01/25/2023] Open
Abstract
Background The evolution of insecticide resistance threatens current malaria control methods, which rely heavily on chemical insecticides. The magnitude of the threat will be determined by the phenotypic expression of resistance in those mosquitoes that can transmit malaria. These differ from the majority of the mosquito population in two main ways; they carry sporozoites (the infectious stage of the Plasmodium parasite) and they are relatively old, as they need to survive the development period of the malaria parasite. This study examines the effects of infection by Plasmodium berghei and of mosquito age on the sensitivity to DDT in a DDT-resistant strain of Anopheles gambiae. Methods DDT-resistant Anopheles gambiae (ZANU) mosquitoes received a blood meal from either a mouse infected with Plasmodium berghei or an uninfected mouse. 10 and 19 days post blood meal the mosquitoes were exposed to 2%, 1% or 0% DDT using WHO test kits. 24 hrs after exposure, mortality and Plasmodium infection status of the mosquitoes were recorded. Results Sensitivity to DDT increased with the mosquitoes’ age and was higher in mosquitoes that had fed on Plasmodium-infected mice than in those that had not been exposed to the parasite. The latter effect was mainly due to the high sensitivity of mosquitoes that had fed on an infected mouse but were not themselves infected, while the sensitivity to DDT was only slightly higher in mosquitoes infected by Plasmodium than in those that had fed on an uninfected mouse. Conclusions The observed pattern indicates a cost of parasite-resistance. It suggests that, in addition to the detrimental effect of insecticide-resistance on control, the continued use of insecticides in a population of insecticide-resistant mosquitoes could select mosquitoes to be more susceptible to Plasmodium infection, thus further decreasing the efficacy of the control.
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Affiliation(s)
- Adam Saddler
- Division of Biology, Faculty of Life Sciences, Imperial College London, Silwood Park Campus, Ascot, Berkshire, SL5 2PZ, UK. .,Faculté des Sciences, Institut de Biologie, Université de Neuchâtel, Rue Emile-Argand 11, CH-2000, Neuchâtel, Switzerland. .,Department of Health Interventions, Swiss Tropical and Public Health Institute, Socinstrasse, 57, CH-4002, Basel, Switzerland. .,Ifakara Health Institute, Box 74, Bagamoyo, Tanzania. .,University of Basel, Petersplatz 1, Basel, 4003, Switzerland.
| | | | - Jacob C Koella
- Faculté des Sciences, Institut de Biologie, Université de Neuchâtel, Rue Emile-Argand 11, CH-2000, Neuchâtel, Switzerland.
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Oliver SV, Brooke BD. The effect of multiple blood-feeding on the longevity and insecticide resistant phenotype in the major malaria vector Anopheles arabiensis (Diptera: Culicidae). Parasit Vectors 2014; 7:390. [PMID: 25150975 PMCID: PMC4161849 DOI: 10.1186/1756-3305-7-390] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2014] [Accepted: 08/13/2014] [Indexed: 11/10/2022] Open
Abstract
Background Anopheles arabiensis is a major malaria vector in Africa. Adult females are likely to imbibe multiple blood meals during their lifetime. This results in regular exposure to potential toxins and blood-meal induced oxidative stress. Defence responses to these stressors may affect other factors of epidemiological significance, such as insecticide resistance and longevity. The aims of this study were to examine the effect of multiple blood-feeding on insecticide tolerance/resistance with increasing age, to assess the underlying biochemical mechanisms for the responses recorded, and to assess the effect of multiple blood-feeding on the life histories of adult females drawn from insecticide resistant and susceptible laboratory reared An. arabiensis. Methods Laboratory reared An. arabiensis females from an insecticide resistant and an insecticide susceptible colony were offered either a single blood meal or multiple blood meals at 3-day intervals. Their tolerance or resistance to insecticide was then monitored by WHO bioassay four hours post blood-feeding. The biochemical basis of the phenotypic response was assessed by examining the effect of blood on detoxification enzyme activity and the effect of blood-meals on detoxification enzyme activity in ageing mosquitoes. Results Control cohorts that were not offered any blood meals showed steadily decreasing levels of insecticide tolerance/resistance with age, whereas a single blood meal significantly increased tolerance/resistance primarily at the age of three days. The expression of resistance/tolerance in those cohorts fed multiple blood meals generally showed the least variation with age. These results were consistent following exposure to DDT and pyrethroids but not to malathion. Multiple blood-meals also maintained the DDT and permethrin resistant phenotype, even after treatment females had stopped taking blood-meals. Biochemical analysis suggests that this phenotypic effect in resistant females may be mediated by the maintenance of increased glutathione s-transferase activity as a consequence of multiple blood-feeding. Multiple blood-feeding increased the longevity of insecticide resistant females regardless of their mating status, but only increased the longevity of unmated susceptible females. Conclusion These data suggest that multiple blood-feeding confers a competitive advantage to insecticide resistant females by increased longevity and maintenance of the expression of resistance with age.
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Affiliation(s)
- Shüné V Oliver
- Centre for Opportunistic, Tropical and Hospital Infections, National Institute for Communicable Diseases/NHLS, Sandringham, Johannesburg, South Africa.
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Alout H, Yameogo B, Djogbénou LS, Chandre F, Dabiré RK, Corbel V, Cohuet A. Interplay between Plasmodium infection and resistance to insecticides in vector mosquitoes. J Infect Dis 2014; 210:1464-70. [PMID: 24829465 DOI: 10.1093/infdis/jiu276] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Despite its epidemiological importance, the impact of insecticide resistance on vector-parasite interactions and malaria transmission is poorly understood. Here, we explored the impact of Plasmodium infection on the level of insecticide resistance to dichlorodiphenyltrichloroethane (DDT) in field-caught Anopheles gambiae sensu stricto homozygous for the kdr mutation. Results showed that kdr homozygous mosquitoes that fed on infectious blood were more susceptible to DDT than mosquitoes that fed on noninfectious blood during both ookinete development (day 1 after the blood meal) and oocyst maturation (day 7 after the blood meal) but not during sporozoite invasion of the salivary glands. Plasmodium falciparum infection seemed to impose a fitness cost on mosquitoes by reducing the ability of kdr homozygous A. gambiae sensu stricto to survive exposure to DDT. These results suggest an interaction between Plasmodium infection and the insecticide susceptibility of mosquitoes carrying insecticide-resistant alleles. We discuss this finding in relation to vector control efficacy.
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Affiliation(s)
- Haoues Alout
- Institut de Recherche pour le Développement, Maladies Infectieuses et Vecteurs, Ecologie, Génétique, Evolution et Contrôle, UM1-UM2-CNRS5290-IRD 224, Montpellier, France Institut de Recherche en Sciences de la Santé, Bobo-Dioulasso, Burkina Faso
| | - Bienvenue Yameogo
- Institut de Recherche en Sciences de la Santé, Bobo-Dioulasso, Burkina Faso
| | | | - Fabrice Chandre
- Institut de Recherche pour le Développement, Maladies Infectieuses et Vecteurs, Ecologie, Génétique, Evolution et Contrôle, UM1-UM2-CNRS5290-IRD 224, Montpellier, France
| | | | - Vincent Corbel
- Institut de Recherche pour le Développement, Maladies Infectieuses et Vecteurs, Ecologie, Génétique, Evolution et Contrôle, UM1-UM2-CNRS5290-IRD 224, Montpellier, France Department of Entomology, Faculty of Agriculture, Kasetsart University, Bangkok, Thailand
| | - Anna Cohuet
- Institut de Recherche pour le Développement, Maladies Infectieuses et Vecteurs, Ecologie, Génétique, Evolution et Contrôle, UM1-UM2-CNRS5290-IRD 224, Montpellier, France Institut de Recherche en Sciences de la Santé, Bobo-Dioulasso, Burkina Faso
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