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Mseti JJ, Maasayi MS, Lugenge AG, Mpelepele AB, Kibondo UA, Tenywa FC, Odufuwa OG, Tambwe MM, Moore SJ. Temperature, mosquito feeding status and mosquito density influence the measured bio-efficacy of insecticide-treated nets in cone assays. Parasit Vectors 2024; 17:159. [PMID: 38549097 PMCID: PMC10979578 DOI: 10.1186/s13071-024-06210-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2023] [Accepted: 02/22/2024] [Indexed: 04/01/2024] Open
Abstract
BACKGROUND The WHO cone bioassay is routinely used to evaluate the bioefficacy of insecticide-treated nets (ITNs) for product pre-qualification and confirmation of continued ITN performance during operational monitoring. Despite its standardized nature, variability is often observed between tests. We investigated the influence of temperature in the testing environment, mosquito feeding status and mosquito density on cone bioassay results. METHODS Cone bioassays were conducted on MAGNet (alphacypermethrin) and Veeralin (alphacypermethrin and piperonyl butoxide (PBO)) ITNs, using laboratory-reared pyrethroid-resistant Anopheles funestus sensu stricto (FUMOZ strain) mosquitoes. Three experiments were conducted using standard cone bioassays following WHO-recommended test parameters, with one variable changed in each bioassay: (i) environmental temperature during exposure: 22-23 °C, 26-27 °C, 29-30 °C and 32-33 °C; (ii) feeding regimen before exposure: sugar starved for 6 h, blood-fed or sugar-fed; and (iii) mosquito density per cone: 5, 10, 15 and 20 mosquitoes. For each test, 15 net samples per treatment arm were tested with four cones per sample (N = 60). Mortality after 24, 48 and 72 h post-exposure to ITNs was recorded. RESULTS There was a notable influence of temperature, feeding status and mosquito density on An. funestus mortality for both types of ITNs. Mortality at 24 h post-exposure was significantly higher at 32-33 °C than at 26-27 °C for both the MAGNet [19.33% vs 7%; odds ratio (OR): 3.96, 95% confidence interval (CI): 1.99-7.87, P < 0.001] and Veeralin (91% vs 47.33%; OR: 22.20, 95% CI: 11.45-43.05, P < 0.001) ITNs. Mosquito feeding status influenced the observed mortality. Relative to sugar-fed mosquitoes, The MAGNet ITNs induced higher mortality among blood-fed mosquitoes (7% vs 3%; OR: 2.23, 95% CI: 0.94-5.27, P = 0.068) and significantly higher mortality among starved mosquitoes (8% vs 3%, OR: 2.88, 95% CI: 1.25-6.63, P = 0.013); in comparison, the Veeralin ITNs showed significantly lower mortality among blood-fed mosquitoes (43% vs 57%; OR: 0.56, 95% CI: 0.38-0.81, P = 0.002) and no difference for starved mosquitoes (58% vs 57%; OR: 1.05, 95% CI: 0.72-1.51, P = 0.816). Mortality significantly increased with increasing mosquito density for both the MAGNet (e.g. 5 vs 10 mosquitoes: 7% vs 12%; OR: 1.81, 95% CI: 1.03-3.20, P = 0.040) and Veeralin (e.g. 5 vs 10 mosquitoes: 58% vs 71%; OR 2.06, 95% CI: 1.24-3.42, P = 0.005) ITNs. CONCLUSIONS The results of this study highlight that the testing parameters temperature, feeding status and mosquito density significantly influence the mortality measured in cone bioassays. Careful adherence to testing parameters outlined in WHO ITN testing guidelines will likely improve the repeatability of studies within and between product testing facilities.
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Affiliation(s)
- Jilly Jackson Mseti
- Vector Control Product Testing Unit, Environmental Health and Ecological Science Department, Ifakara Health Institute, 74, Bagamoyo, Tanzania.
- School of Life Sciences and Bioengineering, The Nelson Mandela African Institution of Science and Technology (NM-AIST), 447, Arusha, Tanzania.
| | - Masudi Suleiman Maasayi
- Vector Control Product Testing Unit, Environmental Health and Ecological Science Department, Ifakara Health Institute, 74, Bagamoyo, Tanzania
- School of Life Sciences and Bioengineering, The Nelson Mandela African Institution of Science and Technology (NM-AIST), 447, Arusha, Tanzania
| | - Aidi Galus Lugenge
- Vector Control Product Testing Unit, Environmental Health and Ecological Science Department, Ifakara Health Institute, 74, Bagamoyo, Tanzania
- School of Life Sciences and Bioengineering, The Nelson Mandela African Institution of Science and Technology (NM-AIST), 447, Arusha, Tanzania
| | - Ahmadi B Mpelepele
- Vector Control Product Testing Unit, Environmental Health and Ecological Science Department, Ifakara Health Institute, 74, Bagamoyo, Tanzania
| | - Ummi Abdul Kibondo
- Vector Control Product Testing Unit, Environmental Health and Ecological Science Department, Ifakara Health Institute, 74, Bagamoyo, Tanzania
| | - Frank Chelestino Tenywa
- Vector Control Product Testing Unit, Environmental Health and Ecological Science Department, Ifakara Health Institute, 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
| | - Olukayode G Odufuwa
- Vector Control Product Testing Unit, Environmental Health and Ecological Science Department, Ifakara Health Institute, 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
| | - Mgeni Mohamed Tambwe
- Vector Control Product Testing Unit, Environmental Health and Ecological Science Department, Ifakara Health Institute, 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, 74, Bagamoyo, Tanzania
- School of Life Sciences and Bioengineering, The Nelson Mandela African Institution of Science and Technology (NM-AIST), 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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Matope A, Lees RS, Spiers A, Foster GM. A bioassay method validation framework for laboratory and semi-field tests used to evaluate vector control tools. Malar J 2023; 22:289. [PMID: 37770855 PMCID: PMC10540336 DOI: 10.1186/s12936-023-04717-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2023] [Accepted: 09/13/2023] [Indexed: 09/30/2023] Open
Abstract
Vector control interventions play a fundamental role in the control and elimination of vector-borne diseases. The evaluation of vector control products relies on bioassays, laboratory and semi-field tests using live insects to assess the product's effectiveness. Bioassay method development requires a rigorous validation process to ensure that relevant methods are used to capture appropriate entomological endpoints which accurately and precisely describe likely efficacy against disease vectors as well as product characteristics within the manufacturing tolerance ranges for insecticide content specified by the World Health Organization. Currently, there are no standardized guidelines for bioassay method validation in vector control. This report presents a framework for bioassay validation that draws on accepted validation processes from the chemical and healthcare fields and which can be applied for evaluating bioassays and semi-field tests in vector control. The validation process has been categorized into four stages: preliminary development; feasibility experiments; internal validation, and external validation. A properly validated method combined with an appropriate experimental design and data analyses that account for both the variability of the method and the product is needed to generate reliable estimates of product efficacy to ensure that at-risk communities have timely access to safe and reliable vector control products.
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Affiliation(s)
- Agnes Matope
- Vector Biology Department, Liverpool School of Tropical Medicine, Pembroke Place, Liverpool, L3 5QA, UK
| | - Rosemary S Lees
- Vector Biology Department, Liverpool School of Tropical Medicine, Pembroke Place, Liverpool, L3 5QA, UK
- Innovation to Impact (I2I), Liverpool School of Tropical Medicine, Pembroke Place, Liverpool, L3 5QA, UK
| | - Angus Spiers
- Innovation to Impact (I2I), Liverpool School of Tropical Medicine, Pembroke Place, Liverpool, L3 5QA, UK
| | - Geraldine M Foster
- Vector Biology Department, Liverpool School of Tropical Medicine, Pembroke Place, Liverpool, L3 5QA, UK.
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Suh PF, Elanga-Ndille E, Tchouakui M, Sandeu MM, Tagne D, Wondji C, Ndo C. Impact of insecticide resistance on malaria vector competence: a literature review. Malar J 2023; 22:19. [PMID: 36650503 PMCID: PMC9847052 DOI: 10.1186/s12936-023-04444-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2022] [Accepted: 01/04/2023] [Indexed: 01/18/2023] Open
Abstract
Since its first report in Anopheles mosquitoes in 1950s, insecticide resistance has spread very fast to most sub-Saharan African malaria-endemic countries, where it is predicted to seriously jeopardize the success of vector control efforts, leading to rebound of disease cases. Supported mainly by four mechanisms (metabolic resistance, target site resistance, cuticular resistance, and behavioural resistance), this phenomenon is associated with intrinsic changes in the resistant insect vectors that could influence development of invading Plasmodium parasites. A literature review was undertaken using Pubmed database to collect articles evaluating directly or indiretly the impact of insecticide resistance and the associated mechanisms on key determinants of malaria vector competence including sialome composition, anti-Plasmodium immunity, intestinal commensal microbiota, and mosquito longevity. Globally, the evidence gathered is contradictory even though the insecticide resistant vectors seem to be more permissive to Plasmodium infections. The actual body of knowledge on key factors to vectorial competence, such as the immunity and microbiota communities of the insecticide resistant vector is still very insufficient to definitively infer on the epidemiological importance of these vectors against the susceptible counterparts. More studies are needed to fill important knowledge gaps that could help predicting malaria epidemiology in a context where the selection and spread of insecticide resistant vectors is ongoing.
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Affiliation(s)
- Pierre Fongho Suh
- Department of Parasitology and Microbiology, Centre for Research in Infectious Diseases, P.O. Box 13591, Yaoundé, Cameroon
- Faculty of Sciences, University of Yaoundé I, P.O. Box 837, Yaoundé, Cameroon
| | - Emmanuel Elanga-Ndille
- Department of Medical Entomology, Centre for Research in Infectious Diseases, P.O. Box 13591, Yaoundé, Cameroon
| | - Magellan Tchouakui
- Department of Medical Entomology, Centre for Research in Infectious Diseases, P.O. Box 13591, Yaoundé, Cameroon
| | - Maurice Marcel Sandeu
- Department of Medical Entomology, Centre for Research in Infectious Diseases, P.O. Box 13591, Yaoundé, Cameroon
- Department of Microbiology and Infectious Diseases, School of Veterinary Medicine and Sciences, University of Ngaoundéré, P.O. Box 454, Ngaoundéré, Cameroon
| | - Darus Tagne
- Department of Parasitology and Microbiology, Centre for Research in Infectious Diseases, P.O. Box 13591, Yaoundé, Cameroon
- Faculty of Sciences, University of Douala, P.O. Box 24157, Douala, Cameroon
| | - Charles Wondji
- Department of Parasitology and Microbiology, Centre for Research in Infectious Diseases, P.O. Box 13591, Yaoundé, Cameroon
- Vector Biology Department, Liverpool School of Tropical Medicine, Pembroke Place, Liverpool, L3 5QA, UK
| | - Cyrille Ndo
- Department of Parasitology and Microbiology, Centre for Research in Infectious Diseases, P.O. Box 13591, Yaoundé, Cameroon.
- Department of Biological Sciences, Faculty of Medicine and Pharmaceutical Sciences, University of Douala, P.O. Box 24157, Douala, Cameroon.
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Joseph Matiya D, Philbert AB, Kidima WB, Matowo JJ. The Effect of Plasmodium falciparum (Welch) (Haemospororida: Plasmodiidae) Infection on the Susceptibility of Anopheles gambiae s.l. and Anopheles funestus (Diptera: Culicidae) to Pyrethroid Insecticides in the North-Western and South-Eastern, Tanzania. JOURNAL OF MEDICAL ENTOMOLOGY 2023; 60:112-121. [PMID: 36287642 DOI: 10.1093/jme/tjac163] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/22/2022] [Indexed: 06/16/2023]
Abstract
The rapid development of insecticide resistance in malaria vectors threatens insecticide-based interventions. It is hypothesized that infection of insecticide-resistant vectors with Plasmodium parasites increases their vulnerability to insecticides, thus assuring the effectiveness of insecticide-based strategies for malaria control. Nonetheless, there is limited field data to support this. We investigated the effect of the Plasmodium falciparum infection on the susceptibility of Anopheles gambiae s.l. and Anopheles funestus to pyrethroids in south-eastern (Kilombero) and north-western (Muleba), Tanzania. The wild-collected mosquitoes were tested against 0.05% deltamethrin and 0.75% permethrin, then assessed for sporozoite rate and resistant gene (kdr) mutations. All Anopheles gambiae s.l. from Kilombero were An. arabiensis (Patton, 1905) while those from Muleba were 87% An. gambiae s.s (Giles, 1902) and 13% An. Arabiensis. High levels of pyrethroid resistance were observed in both areas studied. The kdr mutation was only detected in An. gambiae s.s. at the frequency of 100% in survivors and 97% in dead mosquitoes. The P. falciparum sporozoite rates were slightly higher in susceptible than in resistant mosquitoes. In Muleba, sporozoite rates in An. gambiae s.l. were 8.1% and 6.4% in dead mosquitoes and survivors, respectively (SRR = 1.28, p = 0.19). The sporozoite rates in Kilombero were 1.3% and 0.7% in the dead and survived mosquitoes, respectively (sporozoite rate ratio (SRR) = 1.9, p = 0.33). In An. funestus group sporozoite rates were 6.2% and 4.4% in dead and survived mosquitoes, respectively (SRR = 1.4, p = 0.54). These findings indicate that insecticides might still be effective in malaria control despite the rapid development of insecticide resistance in malaria vectors.
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Affiliation(s)
- Deokary Joseph Matiya
- Dar es Salaam University College of Education (DUCE), PO Box 2329, Dar es Salaam, Tanzania
- University of Dar es Salaam (UDSM), PO Box 35064, Dar es Salaam, Tanzania
| | - Anitha B Philbert
- University of Dar es Salaam (UDSM), PO Box 35064, Dar es Salaam, Tanzania
| | - Winifrida B Kidima
- University of Dar es Salaam (UDSM), PO Box 35064, Dar es Salaam, Tanzania
| | - Johnson J Matowo
- Kilimanjaro Christian Medical University College (KCMUCo), PO Box 2240, Moshi, Tanzania
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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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Agyekum TP, Arko-Mensah J, Botwe PK, Hogarh JN, Issah I, Dadzie SK, Dwomoh D, Billah MK, Robins T, Fobil JN. Relationship between temperature and Anopheles gambiae sensu lato mosquitoes' susceptibility to pyrethroids and expression of metabolic enzymes. Parasit Vectors 2022; 15:163. [PMID: 35527275 PMCID: PMC9080126 DOI: 10.1186/s13071-022-05273-z] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2022] [Accepted: 04/01/2022] [Indexed: 11/29/2022] Open
Abstract
Background Malaria remains one of the most devastating diseases globally, and the control of mosquitoes as the vector is mainly dependent on chemical insecticides. Elevated temperatures associated with future warmer climates could affect mosquitoes' metabolic enzyme expression and increase insecticide resistance, making vector control difficult. Understanding how mosquito rearing temperatures influence their susceptibility to insecticide and expression of metabolic enzymes could aid in the development of novel tools and strategies to control mosquitoes in a future warmer climate. This study evaluated the effects of temperature on the susceptibility of Anopheles gambiae sensu lato (s.l.) mosquitoes to pyrethroids and their expression of metabolic enzymes. Methods Anopheles gambiae s.l. eggs obtained from laboratory-established colonies were reared under eight temperature regimes (25, 28, 30, 32, 34, 36, 38, and 40 °C). Upon adult emergence, 3- to 5-day-old female non-blood-fed mosquitoes were used for susceptibility tests following the World Health Organization (WHO) bioassay protocol. Batches of 20–25 mosquitoes from each temperature regime (25–34 °C) were exposed to two pyrethroid insecticides (0.75% permethrin and 0.05% deltamethrin). In addition, the levels of four metabolic enzymes (α-esterase, β-esterase, glutathione S-transferase [GST], and mixed-function oxidase [MFO]) were examined in mosquitoes that were not exposed and those that were exposed to pyrethroids. Results Mortality in An. gambiae s.l. mosquitoes exposed to deltamethrin and permethrin decreased at temperatures above 28 °C. In addition, mosquitoes reared at higher temperatures were more resistant and had more elevated enzyme levels than those raised at low temperatures. Overall, mosquitoes that survived after being exposed to pyrethroids had higher levels of metabolic enzymes than those that were not exposed to pyrethroids. Conclusions This study provides evidence that elevated temperatures decreased An. gambiae s.l. mosquitoes' susceptibility to pyrethroids and increased the expression of metabolic enzymes. This evidence suggests that elevated temperatures projected in a future warmer climate could increase mosquitoes' resistance to insecticides and complicate malaria vector control measures. This study therefore provides vital information, and suggests useful areas of future research, on the effects of temperature variability on mosquitoes that could guide vector control measures in a future warmer climate. Graphical Abstract ![]()
Supplementary Information The online version contains supplementary material available at 10.1186/s13071-022-05273-z.
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Affiliation(s)
- Thomas Peprah Agyekum
- Department of Biological, Environmental and Occupational Health Sciences, School of Public Health, University of Ghana, P.O. Box L.G. 13, Accra, Ghana.
| | - John Arko-Mensah
- Department of Biological, Environmental and Occupational Health Sciences, School of Public Health, University of Ghana, P.O. Box L.G. 13, Accra, Ghana
| | - Paul Kingsley Botwe
- Department of Biological, Environmental and Occupational Health Sciences, School of Public Health, University of Ghana, P.O. Box L.G. 13, Accra, Ghana
| | - Jonathan Nartey Hogarh
- Department of Environmental Science, Kwame Nkrumah University of Science and Technology, Kumasi, Ghana
| | - Ibrahim Issah
- Department of Biological, Environmental and Occupational Health Sciences, School of Public Health, University of Ghana, P.O. Box L.G. 13, Accra, Ghana
| | - Samuel Kweku Dadzie
- Parasitology Department, Noguchi Memorial Institute for Medical Research (NMIMR), University of Ghana, P.O. Box LG 581, Accra, Ghana
| | - Duah Dwomoh
- Department of Biostatistics, School of Public Health, College of Health Sciences, University of Ghana, Legon, Ghana
| | - Maxwell Kelvin Billah
- Department of Animal Biology and Conservation Science, University of Ghana, P.O. Box L.G. 67, Accra, Ghana
| | - Thomas Robins
- Department of Environmental Health Sciences, University of Michigan, 1415 Washington Heights, Ann Arbor, MI, 48109, USA
| | - Julius Najah Fobil
- Department of Biological, Environmental and Occupational Health Sciences, School of Public Health, University of Ghana, P.O. Box L.G. 13, Accra, Ghana
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Medjigbodo AA, Djogbénou LS, Djihinto OY, Akoton RB, Abbey E, Kakossou RM, Sonounameto EG, Salavi EBJ, Djossou L, Badolo A. Putative pleiotropic effects of the knockdown resistance (L1014F) allele on the life-history traits of Anopheles gambiae. Malar J 2021; 20:480. [PMID: 34930272 PMCID: PMC8686585 DOI: 10.1186/s12936-021-04005-5] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2020] [Accepted: 12/03/2021] [Indexed: 11/23/2022] Open
Abstract
Background Existing mechanisms of insecticide resistance are known to help the survival of mosquitoes following contact with chemical compounds, even though they could negatively affect the life-history traits of resistant malaria vectors. In West Africa, the knockdown resistance mechanism kdrR (L1014F) is the most common. However, little knowledge is available on its effects on mosquito life-history traits. The fitness effects associated with this knockdown resistance allele in Anopheles gambiae sensu stricto (s.s.) were investigated in an insecticide-free laboratory environment. Methods The life-history traits of Kisumu (susceptible) and KisKdr (kdr resistant) strains of An. gambiae s.s. were compared. Larval survivorship and pupation rate were assessed as well as fecundity and fertility of adult females. Female mosquitoes of both strains were directly blood fed through artificial membrane assays and then the blood-feeding success, blood volume and adult survivorship post-blood meal were assessed. Results The An. gambiae mosquitoes carrying the kdrR allele (KisKdr) laid a reduced number of eggs. The mean number of larvae in the susceptible strain Kisumu was three-fold overall higher than that seen in the KisKdr strain with a significant difference in hatching rates (81.89% in Kisumu vs 72.89% in KisKdr). The KisKdr larvae had a significant higher survivorship than that of Kisumu. The blood-feeding success was significantly higher in the resistant mosquitoes (84%) compared to the susceptible ones (34.75%). However, the mean blood volume was 1.36 µL/mg, 1.45 µL/mg and 1.68 µL/mg in Kisumu, homozygote and heterozygote KisKdr mosquitoes, respectively. After blood-feeding, the heterozygote KisKdr mosquitoes displayed highest survivorship when compared to that of Kisumu. Conclusions The presence of the knockdown resistance allele appears to impact the life-history traits, such as fecundity, fertility, larval survivorship, and blood-feeding behaviour in An. gambiae. These data could help to guide the implementation of more reliable strategies for the control of malaria vectors.
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Affiliation(s)
- Adandé A Medjigbodo
- Tropical Infectious Diseases Research Centre (TIDRC), University of Abomey-Calavi, 01BP 526, Cotonou, Benin.,Laboratory of Fundamental and Applied Entomology, University Joseph Ki-Zerbo, BP 7021, Ouagadougou 03, Burkina Faso.,Regional Institute of Public Health/University of Abomey-Calavi, BP 384, Ouidah, Benin
| | - Luc S Djogbénou
- Tropical Infectious Diseases Research Centre (TIDRC), University of Abomey-Calavi, 01BP 526, Cotonou, Benin. .,Regional Institute of Public Health/University of Abomey-Calavi, BP 384, Ouidah, Benin. .,Department of Vector Biology, Liverpool School of Tropical Medicine, Pembroke Place, Liverpool, L3 5QA, UK.
| | - Oswald Y Djihinto
- Tropical Infectious Diseases Research Centre (TIDRC), University of Abomey-Calavi, 01BP 526, Cotonou, Benin.,Regional Institute of Public Health/University of Abomey-Calavi, BP 384, Ouidah, Benin
| | - Romaric B Akoton
- Tropical Infectious Diseases Research Centre (TIDRC), University of Abomey-Calavi, 01BP 526, Cotonou, Benin
| | - Emmanuella Abbey
- Tropical Infectious Diseases Research Centre (TIDRC), University of Abomey-Calavi, 01BP 526, Cotonou, Benin.,Regional Institute of Public Health/University of Abomey-Calavi, BP 384, Ouidah, Benin
| | - Rosaria M Kakossou
- Tropical Infectious Diseases Research Centre (TIDRC), University of Abomey-Calavi, 01BP 526, Cotonou, Benin.,Regional Institute of Public Health/University of Abomey-Calavi, BP 384, Ouidah, Benin
| | - Eric G Sonounameto
- Tropical Infectious Diseases Research Centre (TIDRC), University of Abomey-Calavi, 01BP 526, Cotonou, Benin.,Regional Institute of Public Health/University of Abomey-Calavi, BP 384, Ouidah, Benin
| | - Esther B J Salavi
- Tropical Infectious Diseases Research Centre (TIDRC), University of Abomey-Calavi, 01BP 526, Cotonou, Benin.,Regional Institute of Public Health/University of Abomey-Calavi, BP 384, Ouidah, Benin
| | - Laurette Djossou
- Regional Institute of Public Health/University of Abomey-Calavi, BP 384, Ouidah, Benin
| | - Athanase Badolo
- Laboratory of Fundamental and Applied Entomology, University Joseph Ki-Zerbo, BP 7021, Ouagadougou 03, Burkina Faso
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8
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Namias A, Jobe NB, Paaijmans KP, Huijben S. The need for practical insecticide-resistance guidelines to effectively inform mosquito-borne disease control programs. eLife 2021; 10:e65655. [PMID: 34355693 PMCID: PMC8346280 DOI: 10.7554/elife.65655] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2020] [Accepted: 07/26/2021] [Indexed: 11/13/2022] Open
Abstract
Monitoring local mosquito populations for insecticide resistance is critical for effective vector-borne disease control. However, widely used phenotypic assays, which are designed to monitor the emergence and spread of insecticide resistance (technical resistance), do not translate well to the efficacy of vector control products to suppress mosquito numbers in the field (practical resistance). This is because standard testing conditions such as environmental conditions, exposure dose, and type of substrate differ dramatically from those experienced by mosquitoes under field conditions. In addition, field mosquitoes have considerably different physiological characteristics such as age and blood-feeding status. Beyond this, indirect impacts of insecticide resistance and/or exposure on mosquito longevity, pathogen development, host-seeking behavior, and blood-feeding success impact disease transmission. Given the limited number of active ingredients currently available and the observed discordance between resistance and disease transmission, we conclude that additional testing guidelines are needed to determine practical resistance-the efficacy of vector control tools under relevant local conditions- in order to obtain programmatic impact.
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Affiliation(s)
- Alice Namias
- Département de Biologie, Ecole Normale Supérieure, PSL Research University, Paris, France
- Institut des Sciences de l'Evolution de Montpellier (ISEM), Université de Montpellier, CNRS, IRD, EPHE, Montpellier, France
| | - Ndey Bassin Jobe
- Center for Evolution and Medicine, School of Life Sciences, Arizona State University, Life Sciences C, Tempe, United States
| | - Krijn Petrus Paaijmans
- Center for Evolution and Medicine, School of Life Sciences, Arizona State University, Life Sciences C, Tempe, United States
- The Biodesign Center for Immunotherapy, Vaccines and Virotherapy, Arizona State University, Biodesign Institute, Tempe, United States
- ISGlobal, Carrer del Rosselló, Barcelona, Spain
- Centro de Investigação em Saúde de Manhiça (CISM), Distrito da Manhiça, Mozambique
| | - Silvie Huijben
- Center for Evolution and Medicine, School of Life Sciences, Arizona State University, Life Sciences C, Tempe, United States
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9
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Agyekum TP, Botwe PK, Arko-Mensah J, Issah I, Acquah AA, Hogarh JN, Dwomoh D, Robins TG, Fobil JN. A Systematic Review of the Effects of Temperature on Anopheles Mosquito Development and Survival: Implications for Malaria Control in a Future Warmer Climate. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2021; 18:ijerph18147255. [PMID: 34299706 PMCID: PMC8306597 DOI: 10.3390/ijerph18147255] [Citation(s) in RCA: 26] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/02/2021] [Revised: 06/17/2021] [Accepted: 06/22/2021] [Indexed: 12/17/2022]
Abstract
The rearing temperature of the immature stages can have a significant impact on the life-history traits and the ability of adult mosquitoes to transmit diseases. This review assessed published evidence of the effects of temperature on the immature stages, life-history traits, insecticide susceptibility, and expression of enzymes in the adult Anopheles mosquito. Original articles published through 31 March 2021 were systematically retrieved from Scopus, Google Scholar, Science Direct, PubMed, ProQuest, and Web of Science databases. After applying eligibility criteria, 29 studies were included. The review revealed that immature stages of An. arabiensis were more tolerant (in terms of survival) to a higher temperature than An. funestus and An. quadriannulatus. Higher temperatures resulted in smaller larval sizes and decreased hatching and pupation time. The development rate and survival of An. stephensi was significantly reduced at a higher temperature than a lower temperature. Increasing temperatures decreased the longevity, body size, length of the gonotrophic cycle, and fecundity of Anopheles mosquitoes. Higher rearing temperatures increased pyrethroid resistance in adults of the An. arabiensis SENN DDT strain, and increased pyrethroid tolerance in the An. arabiensis SENN strain. Increasing temperature also significantly increased Nitric Oxide Synthase (NOS) expression and decreased insecticide toxicity. Both extreme low and high temperatures affect Anopheles mosquito development and survival. Climate change could have diverse effects on Anopheles mosquitoes. The sensitivities of Anopeheles mosquitoes to temperature differ from species to species, even among the same complex. Notwithstanding, there seem to be limited studies on the effects of temperature on adult life-history traits of Anopheles mosquitoes, and more studies are needed to clarify this relationship.
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Affiliation(s)
- Thomas P. Agyekum
- Department of Biological, Environmental and Occupational Health Sciences, School of Public Health, University of Ghana, Accra 00233, Ghana; (P.K.B.); (J.A.-M.); (I.I.); (A.A.A.); (J.N.F.)
- Correspondence: or
| | - Paul K. Botwe
- Department of Biological, Environmental and Occupational Health Sciences, School of Public Health, University of Ghana, Accra 00233, Ghana; (P.K.B.); (J.A.-M.); (I.I.); (A.A.A.); (J.N.F.)
| | - John Arko-Mensah
- Department of Biological, Environmental and Occupational Health Sciences, School of Public Health, University of Ghana, Accra 00233, Ghana; (P.K.B.); (J.A.-M.); (I.I.); (A.A.A.); (J.N.F.)
| | - Ibrahim Issah
- Department of Biological, Environmental and Occupational Health Sciences, School of Public Health, University of Ghana, Accra 00233, Ghana; (P.K.B.); (J.A.-M.); (I.I.); (A.A.A.); (J.N.F.)
| | - Augustine A. Acquah
- Department of Biological, Environmental and Occupational Health Sciences, School of Public Health, University of Ghana, Accra 00233, Ghana; (P.K.B.); (J.A.-M.); (I.I.); (A.A.A.); (J.N.F.)
| | - Jonathan N. Hogarh
- Department of Environmental Science, Kwame Nkrumah University of Science and Technology, Kumasi 00233, Ghana;
| | - Duah Dwomoh
- Department of Biostatistics, School of Public Health, College of Health Sciences, University of Ghana, Accra 00233, Ghana;
| | - Thomas G. Robins
- Department of Environmental Health Sciences, University of Michigan, 1415 Washington Heights, Ann Arbor, MI 48109, USA;
| | - Julius N. Fobil
- Department of Biological, Environmental and Occupational Health Sciences, School of Public Health, University of Ghana, Accra 00233, Ghana; (P.K.B.); (J.A.-M.); (I.I.); (A.A.A.); (J.N.F.)
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10
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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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