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Takken W, Charlwood D, Lindsay SW. The behaviour of adult Anopheles gambiae, sub-Saharan Africa's principal malaria vector, and its relevance to malaria control: a review. Malar J 2024; 23:161. [PMID: 38783348 PMCID: PMC11112813 DOI: 10.1186/s12936-024-04982-3] [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: 10/03/2023] [Accepted: 05/11/2024] [Indexed: 05/25/2024] Open
Abstract
BACKGROUND Mosquitoes of the Anopheles gambiae complex are one of the major vectors of malaria in sub-Saharan Africa. Their ability to transmit this disease of major public health importance is dependent on their abundance, biting behaviour, susceptibility and their ability to survive long enough to transmit malaria parasites. A deeper understanding of this behaviour can be exploited for improving vector surveillance and malaria control. FINDINGS Adult mosquitoes emerge from aquatic habitats at dusk. After a 24 h teneral period, in which the cuticle hardens and the adult matures, they may disperse at random and search upwind for a mate or to feed. Mating generally takes place at dusk in swarms that form over species-specific 'markers'. Well-nourished females may mate before blood-feeding, but the reverse is true for poorly-nourished insects. Females are monogamous and only mate once whilst males, that only feed on nectar, swarm nightly and can potentially mate up to four times. Females are able to locate hosts by following their carbon dioxide and odour gradients. When in close proximity to the host, visual cues, temperature and relative humidity are also used. Most blood-feeding occurs at night, indoors, with mosquitoes entering houses mainly through gaps between the roof and the walls. With the exception of the first feed, females are gonotrophically concordant and a blood meal gives rise to a complete egg batch. Egg development takes two or three days depending on temperature. Gravid females leave their resting sites at dusk. They are attracted by water gradients and volatile chemicals that provide a suitable aquatic habitat in which to lay their eggs. CONCLUSION Whilst traditional interventions, using insecticides, target mosquitoes indoors, additional protection can be achieved using spatial repellents outdoors, attractant traps or house modifications to prevent mosquito entry. Future research on the variability of species-specific behaviour, movement of mosquitoes across the landscape, the importance of light and vision, reproductive barriers to gene flow, male mosquito behaviour and evolutionary changes in mosquito behaviour could lead to an improvement in malaria surveillance and better methods of control reducing the current over-reliance on the indoor application of insecticides.
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Affiliation(s)
- Willem Takken
- Laboratory of Entomology, Wageningen University & Research, PO Box 16, 6700 AA, Wageningen, The Netherlands.
| | - Derek Charlwood
- Global Health and Tropical Medicine, Instituto de Hygiene e Medicina Tropical, Lisbon, Portugal
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Mwima R, Hui TYJ, Kayondo JK, Burt A. The population genetics of partial diapause, with applications to the aestivating malaria mosquito Anopheles coluzzii. Mol Ecol Resour 2024; 24:e13949. [PMID: 38511493 DOI: 10.1111/1755-0998.13949] [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: 09/05/2023] [Revised: 02/27/2024] [Accepted: 03/08/2024] [Indexed: 03/22/2024]
Abstract
Diapause, a form of dormancy to delay or halt the reproductive development during unfavourable seasons, has evolved in many insect species. One example is aestivation, an adult-stage diapause enhancing malaria vectors' survival during the dry season (DS) and their re-establishment in the next rainy season (RS). This work develops a novel genetic approach to estimate the number or proportion of individuals undergoing diapause, as well as the breeding sizes of the two seasons, using signals from temporal allele frequency dynamics. Our modelling shows the magnitude of drift is dampened at early RS when previously aestivating individuals reappear. Aestivation severely biases the temporal effective population size (N e $$ {N}_e $$ ), leading to overestimation of the DS breeding size by1 / 1 - α 2 $$ 1/{\left(1-\alpha \right)}^2 $$ across 1 year, whereα $$ \alpha $$ is the aestivating proportion. We find sampling breeding individuals in three consecutive seasons starting from an RS is sufficient for parameter estimation, and perform extensive simulations to verify our derivations. This method does not require sampling individuals in the dormant state, the biggest challenge in most studies. We illustrate the method by applying it to a published data set for Anopheles coluzzii mosquitoes from Thierola, Mali. Our method and the expected evolutionary implications are applicable to any species in which a fraction of the population diapauses for more than one generation, and are difficult or impossible to sample during that stage.
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Affiliation(s)
- Rita Mwima
- Department of Entomology, Uganda Virus Research Institute (UVRI), Entebbe, Uganda
- Department of Biotechnical and Diagnostic Sciences, College of Veterinary Medicine, Animal Resources and Biosecurity (COVAB), Makerere University, Kampala, Uganda
| | - Tin-Yu J Hui
- Department of Life Sciences, Imperial College London, Ascot, UK
| | - Jonathan K Kayondo
- Department of Entomology, Uganda Virus Research Institute (UVRI), Entebbe, Uganda
| | - Austin Burt
- Department of Life Sciences, Imperial College London, Ascot, UK
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Mwima R, Hui TYJ, Nanteza A, Burt A, Kayondo JK. Potential persistence mechanisms of the major Anopheles gambiae species complex malaria vectors in sub-Saharan Africa: a narrative review. Malar J 2023; 22:336. [PMID: 37936194 PMCID: PMC10631165 DOI: 10.1186/s12936-023-04775-0] [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: 03/22/2023] [Accepted: 10/30/2023] [Indexed: 11/09/2023] Open
Abstract
The source of malaria vector populations that re-establish at the beginning of the rainy season is still unclear yet knowledge of mosquito behaviour is required to effectively institute control measures. Alternative hypotheses like aestivation, local refugia, migration between neighbouring sites, and long-distance migration (LDM) are stipulated to support mosquito persistence. This work assessed the malaria vector persistence dynamics and examined various studies done on vector survival via these hypotheses; aestivation, local refugia, local or long-distance migration across sub-Saharan Africa, explored a range of methods used, ecological parameters and highlighted the knowledge trends and gaps. The results about a particular persistence mechanism that supports the re-establishment of Anopheles gambiae, Anopheles coluzzii or Anopheles arabiensis in sub-Saharan Africa were not conclusive given that each method used had its limitations. For example, the Mark-Release-Recapture (MRR) method whose challenge is a low recapture rate that affects its accuracy, and the use of time series analysis through field collections whose challenge is the uncertainty about whether not finding mosquitoes during the dry season is a weakness of the conventional sampling methods used or because of hidden shelters. This, therefore, calls for further investigations emphasizing the use of ecological experiments under controlled conditions in the laboratory or semi-field, and genetic approaches, as they are known to complement each other. This review, therefore, unveils and assesses the uncertainties that influence the different malaria vector persistence mechanisms and provides recommendations for future studies.
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Affiliation(s)
- Rita Mwima
- Department of Entomology, Uganda Virus Research Institute (UVRI), Entebbe, Uganda
- Department of Biotechnical and Diagnostic Sciences, College of Veterinary Medicine, Animal Resources and Biosecurity (COVAB), Makerere University, Kampala, Uganda
| | - Tin-Yu J Hui
- Silwood Park Campus, Department of Life Sciences, Imperial College London, Ascot, UK
| | - Ann Nanteza
- Department of Biotechnical and Diagnostic Sciences, College of Veterinary Medicine, Animal Resources and Biosecurity (COVAB), Makerere University, Kampala, Uganda
| | - Austin Burt
- Silwood Park Campus, Department of Life Sciences, Imperial College London, Ascot, UK
| | - Jonathan K Kayondo
- Department of Entomology, Uganda Virus Research Institute (UVRI), Entebbe, Uganda.
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Ibrahim SS, Muhammad A, Hearn J, Weedall GD, Nagi SC, Mukhtar MM, Fadel AN, Mugenzi LJ, Patterson EI, Irving H, Wondji CS. Molecular drivers of insecticide resistance in the Sahelo-Sudanian populations of a major malaria vector Anopheles coluzzii. BMC Biol 2023; 21:125. [PMID: 37226196 DOI: 10.1186/s12915-023-01610-5] [Citation(s) in RCA: 15] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2022] [Accepted: 05/03/2023] [Indexed: 05/26/2023] Open
Abstract
BACKGROUND Information on common markers of metabolic resistance in malaria vectors from countries sharing similar eco-climatic characteristics can facilitate coordination of malaria control. Here, we characterized populations of the major malaria vector Anopheles coluzzii from Sahel region, spanning four sub-Saharan African countries: Nigeria, Niger, Chad and Cameroon. RESULTS Genome-wide transcriptional analysis identified major genes previously implicated in pyrethroid and/or cross-resistance to other insecticides, overexpressed across the Sahel, including CYP450s, glutathione S-transferases, carboxylesterases and cuticular proteins. Several, well-known markers of insecticide resistance were found in high frequencies-including in the voltage-gated sodium channel (V402L, I940T, L995F, I1527T and N1570Y), the acetylcholinesterase-1 gene (G280S) and the CYP4J5-L43F (which is fixed). High frequencies of the epidemiologically important chromosomal inversion polymorphisms, 2La, 2Rb and 2Rc, were observed (~80% for 2Rb and 2Rc). The 2La alternative arrangement is fixed across the Sahel. Low frequencies of these inversions (<10%) were observed in the fully insecticide susceptible laboratory colony of An. coluzzii (Ngoussou). Several of the most commonly overexpressed metabolic resistance genes sit in these three inversions. Two commonly overexpressed genes, GSTe2 and CYP6Z2, were functionally validated. Transgenic Drosophila melanogaster flies expressing GSTe2 exhibited extremely high DDT and permethrin resistance (mortalities <10% in 24h). Serial deletion of the 5' intergenic region, to identify putative nucleotide(s) associated with GSTe2 overexpression, revealed that simultaneous insertion of adenine nucleotide and a transition (T->C), between Forkhead box L1 and c-EST putative binding sites, were responsible for the high overexpression of GSTe2 in the resistant mosquitoes. Transgenic flies expressing CYP6Z2 exhibited marginal resistance towards 3-phenoxybenzylalcohol (a primary product of pyrethroid hydrolysis by carboxylesterases) and a type II pyrethroid, α-cypermethrin. However, significantly higher mortalities were observed in CYP6Z2 transgenic flies compared with controls, on exposure to the neonicotinoid, clothianidin. This suggests a possible bioactivation of clothianidin into a toxic intermediate, which may make it an ideal insecticide against populations of An. coluzzii overexpressing this P450. CONCLUSIONS These findings will facilitate regional collaborations within the Sahel region and refine implementation strategies through re-focusing interventions, improving evidence-based, cross-border policies towards local and regional malaria pre-elimination.
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Affiliation(s)
- Sulaiman S Ibrahim
- Vector Biology Department, Liverpool School of Tropical Medicine (LSTM), Liverpool, L3 5QA, UK.
- Department of Biochemistry, Bayero University, PMB 3011, Kano, Nigeria.
- Centre for Research in Infectious Diseases (CRID), P.O. Box 13591, Yaoundé, Cameroon.
| | - Abdullahi Muhammad
- Vector Biology Department, Liverpool School of Tropical Medicine (LSTM), Liverpool, L3 5QA, UK
- Centre for Biotechnology Research, Bayero University, PMB 3011, Kano, Nigeria
| | - Jack Hearn
- Centre of Epidemiology and Planetary Health, Veterinary & Animal Science, Scotland's Rural College, Inverness, IV2 5NA, UK
| | - Gareth D Weedall
- School of Biological and Environmental Sciences, Liverpool John Moores University, Liverpool, L3 3AF, UK
| | - Sanjay C Nagi
- Vector Biology Department, Liverpool School of Tropical Medicine (LSTM), Liverpool, L3 5QA, UK
| | | | - Amen N Fadel
- Centre for Research in Infectious Diseases (CRID), P.O. Box 13591, Yaoundé, Cameroon
| | - Leon J Mugenzi
- Centre for Research in Infectious Diseases (CRID), P.O. Box 13591, Yaoundé, Cameroon
| | - Edward I Patterson
- Department of Biological Sciences, Brock University, St. Catharines, Ontario, L2S 3A1, Canada
| | - Helen Irving
- Vector Biology Department, Liverpool School of Tropical Medicine (LSTM), Liverpool, L3 5QA, UK
| | - Charles S Wondji
- Vector Biology Department, Liverpool School of Tropical Medicine (LSTM), Liverpool, L3 5QA, UK
- Centre for Research in Infectious Diseases (CRID), P.O. Box 13591, Yaoundé, Cameroon
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Yaro AS, Linton YM, Dao A, Diallo M, Sanogo ZL, Samake D, Ousmane Y, Kouam C, Krajacich BJ, Faiman R, Bamou R, Woo J, Chapman JW, Reynolds DR, Lehmann T. Diversity, composition, altitude, and seasonality of high-altitude windborne migrating mosquitoes in the Sahel: Implications for disease transmission. FRONTIERS IN EPIDEMIOLOGY 2022; 2:1001782. [PMID: 38455321 PMCID: PMC10910920 DOI: 10.3389/fepid.2022.1001782] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/24/2022] [Accepted: 09/16/2022] [Indexed: 03/09/2024]
Abstract
Recent studies have reported Anopheles mosquitoes captured at high-altitude (40-290 m above ground) in the Sahel. Here, we describe this migration modality across genera and species of African Culicidae and examine its implications for disease transmission and control. As well as Anopheles, six other genera-Culex, Aedes, Mansonia, Mimomyia, Lutzia, and Eretmapodites comprised 90% of the 2,340 mosquitoes captured at altitude. Of the 50 molecularly confirmed species (N = 2,107), 33 species represented by multiple specimens were conservatively considered high-altitude windborne migrants, suggesting it is a common migration modality in mosquitoes (31-47% of the known species in Mali), and especially in Culex (45-59%). Overall species abundance varied between 2 and 710 specimens/species (in Ae. vittatus and Cx. perexiguus, respectively). At altitude, females outnumbered males 6:1, and 93% of the females have taken at least one blood meal on a vertebrate host prior to their departure. Most taxa were more common at higher sampling altitudes, indicating that total abundance and diversity are underestimated. High-altitude flight activity was concentrated between June and November coinciding with availability of surface waters and peak disease transmission by mosquitoes. These hallmarks of windborne mosquito migration bolster their role as carriers of mosquito-borne pathogens (MBPs). Screening 921 mosquitoes using pan-Plasmodium assays revealed that thoracic infection rate in these high-altitude migrants was 2.4%, providing a proof of concept that vertebrate pathogens are transported by windborne mosquitoes at altitude. Fourteen of the 33 windborne mosquito species had been reported as vectors to 25 MBPs in West Africa, which represent 32% of the MBPs known in that region and include those that inflict the heaviest burden on human and animal health, such as malaria, yellow fever, dengue, and Rift Valley fever. We highlight five arboviruses that are most likely affected by windborne mosquitoes in West Africa: Rift Valley fever, O'nyong'nyong, Ngari, Pangola, and Ndumu. We conclude that the study of windborne spread of diseases by migrating insects and the development of surveillance to map the sources, routes, and destinations of vectors and pathogens is key to understand, predict, and mitigate existing and new threats of public health.
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Affiliation(s)
- Alpha Seydou Yaro
- Malaria Research and Training Center (MRTC), Faculty of Medicine, Pharmacy and Odonto-Stomatology, Bamako, Mali
| | - Yvonne-Marie Linton
- Walter Reed Biosystematics Unit, Smithsonian Institution Museum Support Center, Suitland, MD, United States
- Department of Entomology, Smithsonian Institution, National Museum of Natural History, Washington, DC, United States
- One Health Branch, Walter Reed Army Institute of Research, Silver Spring, MD, United States
| | - Adama Dao
- Malaria Research and Training Center (MRTC), Faculty of Medicine, Pharmacy and Odonto-Stomatology, Bamako, Mali
| | - Moussa Diallo
- Malaria Research and Training Center (MRTC), Faculty of Medicine, Pharmacy and Odonto-Stomatology, Bamako, Mali
| | - Zana L. Sanogo
- Malaria Research and Training Center (MRTC), Faculty of Medicine, Pharmacy and Odonto-Stomatology, Bamako, Mali
| | - Djibril Samake
- Malaria Research and Training Center (MRTC), Faculty of Medicine, Pharmacy and Odonto-Stomatology, Bamako, Mali
| | - Yossi Ousmane
- Malaria Research and Training Center (MRTC), Faculty of Medicine, Pharmacy and Odonto-Stomatology, Bamako, Mali
| | - Cedric Kouam
- Laboratory of Malaria and Vector Research, NIAID, NIH, Rockville, MD, United States
| | | | - Roy Faiman
- Laboratory of Malaria and Vector Research, NIAID, NIH, Rockville, MD, United States
| | - Roland Bamou
- Laboratory of Malaria and Vector Research, NIAID, NIH, Rockville, MD, United States
| | - Joshua Woo
- Krieger School of Arts and Sciences, Johns Hopkins University, Baltimore, MD, United States
| | - Jason W. Chapman
- Centre for Ecology and Conservation, and Environment and Sustainability Institute, University of Exeter, Penryn, United Kingdom
- Department of Entomology, College of Plant Protection, Nanjing Agricultural University, Nanjing, China
| | - Don R. Reynolds
- Natural Resources Institute, University of Greenwich, Chatham, United Kingdom
- Rothamsted Research, Harpenden, United Kingdom
| | - Tovi Lehmann
- Laboratory of Malaria and Vector Research, NIAID, NIH, Rockville, MD, United States
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Beeton NJ, Wilkins A, Ickowicz A, Hayes KR, Hosack GR. Spatial modelling for population replacement of mosquito vectors at continental scale. PLoS Comput Biol 2022; 18:e1009526. [PMID: 35648783 PMCID: PMC9191746 DOI: 10.1371/journal.pcbi.1009526] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2021] [Revised: 06/13/2022] [Accepted: 04/22/2022] [Indexed: 11/24/2022] Open
Abstract
Malaria is one of the deadliest vector-borne diseases in the world. Researchers are developing new genetic and conventional vector control strategies to attempt to limit its burden. Novel control strategies require detailed safety assessment to ensure responsible and successful deployments. Anopheles gambiae sensu stricto (s.s.) and Anopheles coluzzii, two closely related subspecies within the species complex Anopheles gambiae sensu lato (s.l.), are among the dominant malaria vectors in sub-Saharan Africa. These two subspecies readily hybridise and compete in the wild and are also known to have distinct niches, each with spatially and temporally varying carrying capacities driven by precipitation and land use factors. We model the spread and persistence of a population-modifying gene drive system in these subspecies across sub-Saharan Africa by simulating introductions of genetically modified mosquitoes across the African mainland and its offshore islands. We explore transmission of the gene drive between the two subspecies that arise from different hybridisation mechanisms, the effects of both local dispersal and potential wind-aided migration to the spread, and the development of resistance to the gene drive. Given the best current available knowledge on the subspecies’ life histories, we find that an introduced gene drive system with typical characteristics can plausibly spread from even distant offshore islands to the African mainland with the aid of wind-driven migration, with resistance beginning to take over within a decade. Our model accounts for regional to continental scale mechanisms, and demonstrates a range of realistic dynamics including the effect of prevailing wind on spread and spatio-temporally varying carrying capacities for subspecies. As a result, it is well-placed to answer future questions relating to mosquito gene drives as important life history parameters become better understood. Conventional control methods have dramatically reduced malaria, but it still kills over 300,000 children in Africa each year, and this number could increase as their effectiveness wanes. Novel control methods using gene drives rapidly reduce or modify malaria vector populations in laboratory settings, and hence are now being considered for field applications. We use modelling to assess how a gene drive might spread and persist in the malaria-carrying subspecies Anopheles gambiae sensu stricto (s.s.) and Anopheles coluzzii. These two subspecies interbreed and compete, so we model how these interactions affect the spread of the drive at a continental scale. In scenarios that allow mosquitoes to travel on prevailing wind currents, we find that a gene drive can potentially spread across national borders—and jump from offshore islands to the African mainland—but spread is eventually arrested when the drive allele is ousted by a resistant allele. As we learn more about the population dynamics of both genetically modified and wild mosquitoes, and as gene drive systems are further developed to allow local containment and evade resistance, our model will be able to answer more detailed questions about how they can be applied in the field effectively and safely.
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Affiliation(s)
- Nicholas J. Beeton
- Data61, CSIRO, 3 Castray Esplanade, Battery Point TAS, Australia
- * E-mail: (NJB); (AW)
| | - Andrew Wilkins
- Mineral Resources, CSIRO, 1 Technology Court, Pullenvale QLD, Australia
- * E-mail: (NJB); (AW)
| | - Adrien Ickowicz
- Data61, CSIRO, 3 Castray Esplanade, Battery Point TAS, Australia
| | - Keith R. Hayes
- Data61, CSIRO, 3 Castray Esplanade, Battery Point TAS, Australia
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Nignan C, Poda BS, Sawadogo SP, Maïga H, Dabiré KR, Gnankine O, Tripet F, Roux O, Diabaté A. Local adaptation and colonization are potential factors affecting sexual competitiveness and mating choice in Anopheles coluzzii populations. Sci Rep 2022; 12:636. [PMID: 35022496 PMCID: PMC8755725 DOI: 10.1038/s41598-021-04704-8] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2021] [Accepted: 12/24/2021] [Indexed: 11/16/2022] Open
Abstract
The mating behaviour of the malaria vector Anopheles gambiae complex is an important aspect of its reproduction biology. The success of mosquito release programmes based on genetic control of malaria crucially depends on competitive mating between both laboratory-reared and wild individuals, and populations from different localities. It is known that intrinsic and extrinsic factors can influence the mating success. This study addressed some of the knowledge gaps about factors influcencing mosquito mating success. In semi-field conditions, the study compared the mating success of three laboratory-reared and wild allopatric An. coluzzii populations originating from ecologically different locations in Burkina Faso. Overall, it was found that colonization reduced the mating competitiveness of both males and females compared to that of wild type individuals. More importly, females were more likely to mate with males of their own population of origin, be it wild or colonised, suggesting that local adaptation affected mate choice. The observations of mating behaviour of colonized and local wild populations revealed that subtle differences in behaviour lead to significant levels of population-specific mating. This is the first study to highlight the importance of local adaptation in the mating success, thereby highlighting the importance of using local strains for mass-rearing and release of An. coluzzii in vector control programmes.
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Affiliation(s)
- Charles Nignan
- Institut de Recherche en Sciences de La Santé (IRSS), Bobo-Dioulasso, Burkina Faso.
- Laboratoire d'Entomologie Fondamentale Et Appliquée, Unité de Formation Et de Recherche en Sciences de La Vie Et de La Terre (UFR-SVT), Université Ouaga I Pr. Joseph KI-ZERBO, Ouagadougou, Burkina Faso.
| | - Bèwadéyir Serge Poda
- Institut de Recherche en Sciences de La Santé (IRSS), Bobo-Dioulasso, Burkina Faso
- Laboratoire d'Entomologie Fondamentale Et Appliquée, Unité de Formation Et de Recherche en Sciences de La Vie Et de La Terre (UFR-SVT), Université Ouaga I Pr. Joseph KI-ZERBO, Ouagadougou, Burkina Faso
- MIVEGEC, IRD, CNRS, University of Montpellier, Montpellier, France
| | | | - Hamidou Maïga
- Institut de Recherche en Sciences de La Santé (IRSS), Bobo-Dioulasso, Burkina Faso
| | - Kounbobr Roch Dabiré
- Institut de Recherche en Sciences de La Santé (IRSS), Bobo-Dioulasso, Burkina Faso
| | - Olivier Gnankine
- Laboratoire d'Entomologie Fondamentale Et Appliquée, Unité de Formation Et de Recherche en Sciences de La Vie Et de La Terre (UFR-SVT), Université Ouaga I Pr. Joseph KI-ZERBO, Ouagadougou, Burkina Faso
| | - Frédéric Tripet
- Centre for Applied Entomology and Parasitology, School of Life Sciences, Keele University, Keele, UK
| | - Olivier Roux
- Institut de Recherche en Sciences de La Santé (IRSS), Bobo-Dioulasso, Burkina Faso
- MIVEGEC, IRD, CNRS, University of Montpellier, Montpellier, France
| | - Abdoulaye Diabaté
- Institut de Recherche en Sciences de La Santé (IRSS), Bobo-Dioulasso, Burkina Faso
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2La Paracentric Chromosomal Inversion and Overexpressed Metabolic Genes Enhance Thermotolerance and Pyrethroid Resistance in the Major Malaria Vector Anopheles gambiae. BIOLOGY 2021; 10:biology10060518. [PMID: 34200806 PMCID: PMC8230517 DOI: 10.3390/biology10060518] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/26/2021] [Revised: 06/05/2021] [Accepted: 06/07/2021] [Indexed: 01/31/2023]
Abstract
Changes in global temperature are impacting the spread/intensity of vector-borne diseases, including malaria, and accelerating evolutionary/adaptive changes in vector species. These changes, including chromosomal inversions and overexpression and/or changes in allele frequencies of thermotolerance-associated genes, may facilitate insecticide resistance through pleiotropy. This study investigated the impact of thermotolerance on pyrethroid resistance in four populations of the malaria vector An. gambiae s.l., from the savanna/sub-Sahel of northern Nigeria. Anopheles coluzzii and An. gambiae s.s. were the only malaria vectors found, sympatric in all the sites, with the former species predominant. High thermotolerance was observed, with no mortality at 38 °C, and LT50 of ~44 °C. Significantly high permethrin resistance was observed (mortality < 50%) in 44 °C heat-hardened (exposure to an intermediately high temperature provides protection to a more severe temperature or insecticide) larvae from two sites, BUK and Pantami, compared with the control, and heat-hardened adult females from Auyo (mortality = 3.00% ± 1.20, χ2 = 5.83, p < 0.01) compared with the control (12.00% ± 4.65). The 2La chromosomal inversion was detected at ~50% in subset of larvae and 58% in subset of adult females genotyped. A significant association was observed (OR = 7.2, p < 0.03) between permethrin resistance and the 2La/+a rearrangement compared with 2L+a/+a, in BUK larvae. For all sites, permethrin resistance correlated with 2La/a homozygosity in adult females (R = 5.02, p = 0.01). qRT-PCR identified six genes commonly induced/overexpressed, including the heat shock protein 70 (AGAP004581) which was 2468× and 5× overexpressed in heat-hardened and permethrin-resistant females, respectively; trehalose-6-phosphate synthase (AGAP008227); and the ionotropic glutamate receptor genes, IR25a (AGAP010272) and IR21a (AGAP008511). This study highlights challenges associated with insecticide-based malaria vector control, and the epidemiological significance of taking climate variables into account for the design/choice of control measures.
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The origin of island populations of the African malaria mosquito, Anopheles coluzzii. Commun Biol 2021; 4:630. [PMID: 34040154 PMCID: PMC8155153 DOI: 10.1038/s42003-021-02168-0] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2021] [Accepted: 04/21/2021] [Indexed: 11/09/2022] Open
Abstract
Anopheles coluzzii is a major malaria vector throughout its distribution in west-central Africa. Here we present a whole-genome study of 142 specimens from nine countries in continental Africa and three islands in the Gulf of Guinea. This sample set covers a large part of this species' geographic range. Our population genomic analyses included a description of the structure of mainland populations, island populations, and connectivity between them. Three genetic clusters are identified among mainland populations and genetic distances (FST) fits an isolation-by-distance model. Genomic analyses are applied to estimate the demographic history and ancestry for each island. Taken together with the unique biogeography and history of human occupation for each island, they present a coherent explanation underlying levels of genetic isolation between mainland and island populations. We discuss the relationship of our findings to the suitability of São Tomé and Príncipe islands as candidate sites for potential field trials of genetic-based malaria control strategies.
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Buxton M, Wasserman RJ, Nyamukondiwa C. Disease Vector Relative Spatio-Temporal Abundances to Water Bodies and Thermal Fitness Across Malaria Endemic Semi-Arid Areas. JOURNAL OF MEDICAL ENTOMOLOGY 2021; 58:682-691. [PMID: 33107574 DOI: 10.1093/jme/tjaa221] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/27/2020] [Indexed: 06/11/2023]
Abstract
The biophysical environment plays an important role in the spatio-temporal abundance and distribution of mosquitoes. This has implications for the spread of vectors and diseases they cause across diverse landscapes. Here, we assessed vector mosquito abundances in relation to large water bodies, from three malaria districts in a semi-arid environment. Furthermore, we explored thermal limits to activity of the dominant and most medically important malaria vector across malaria-endemic areas. Mosquitoes were trapped near permanent water bodies across different districts. Critical thermal limits (critical thermal-maxima and -minima) to activity of wild adults and 4th instar larvae Anopheles arabiensis (Diptera: Culicidae) were assessed. Our results showed that Anopheles spp. dominate mosquito communities across all three districts, but that their numbers were far greater in Okavango than in other regions. At the Okavango sites, the numbers of Anopheles spp. decreased with distance from main water source. Anopheles spp. sampled in this region comprised Anopheles gambiae (Giles,1902) and Anopheles funestus (Giles, 1900) species complexes, with the former dominating in numbers. Thermal activity assays showed An. arabiensis females had wider thermal tolerance windows than males while larval thermal activity limits differed significantly across space. These results confirm that the Okavango district should be prioritized for vector control measures. Moreover, intervention strategies should consider recommendations for proximity effects to large water bodies, given the differential risk associated with distance from water. The wider thermal window on female vectors has implications for possible future malaria transmission and diverse habitat utilization under changing environments.
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Affiliation(s)
- Mmabaledi Buxton
- Department of Biological Sciences and Biotechnology, Botswana International University of Science and Technology, Palapye, Botswana
| | - Ryan J Wasserman
- Department of Biological Sciences and Biotechnology, Botswana International University of Science and Technology, Palapye, Botswana
- Department of Zoology and Entomology, Rhodes University, Makhanda, South Africa
| | - Casper Nyamukondiwa
- Department of Biological Sciences and Biotechnology, Botswana International University of Science and Technology, Palapye, Botswana
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11
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Diversity, dynamics, direction, and magnitude of high-altitude migrating insects in the Sahel. Sci Rep 2020; 10:20523. [PMID: 33239619 PMCID: PMC7688652 DOI: 10.1038/s41598-020-77196-7] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2020] [Accepted: 10/28/2020] [Indexed: 11/08/2022] Open
Abstract
Long-distance migration of insects impacts food security, public health, and conservation–issues that are especially significant in Africa. Windborne migration is a key strategy enabling exploitation of ephemeral havens such as the Sahel, however, its knowledge remains sparse. In this first cross-season investigation (3 years) of the aerial fauna over Africa, we sampled insects flying 40–290 m above ground in Mali, using nets mounted on tethered helium-filled balloons. Nearly half a million insects were caught, representing at least 100 families from thirteen orders. Control nets confirmed that the insects were captured at altitude. Thirteen ecologically and phylogenetically diverse species were studied in detail. Migration of all species peaked during the wet season every year across localities, suggesting regular migrations. Species differed in flight altitude, seasonality, and associated weather conditions. All taxa exhibited frequent flights on southerly winds, accounting for the recolonization of the Sahel from southern source populations. “Return” southward movement occurred in most taxa. Estimates of the seasonal number of migrants per species crossing Mali at latitude 14°N were in the trillions, and the nightly distances traversed reached hundreds of kilometers. The magnitude and diversity of windborne insect migration highlight its importance and impacts on Sahelian and neighboring ecosystems.
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12
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Dhole S, Lloyd AL, Gould F. Gene Drive Dynamics in Natural Populations: The Importance of Density Dependence, Space, and Sex. ANNUAL REVIEW OF ECOLOGY, EVOLUTION, AND SYSTEMATICS 2020; 51:505-531. [PMID: 34366722 PMCID: PMC8340601 DOI: 10.1146/annurev-ecolsys-031120-101013] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
The spread of synthetic gene drives is often discussed in the context of panmictic populations connected by gene flow and described with simple deterministic models. Under such assumptions, an entire species could be altered by releasing a single individual carrying an invasive gene drive, such as a standard homing drive. While this remains a theoretical possibility, gene drive spread in natural populations is more complex and merits a more realistic assessment. The fate of any gene drive released in a population would be inextricably linked to the population's ecology. Given the uncertainty often involved in ecological assessment of natural populations, understanding the sensitivity of gene drive spread to important ecological factors is critical. Here we review how different forms of density dependence, spatial heterogeneity, and mating behaviors can impact the spread of self-sustaining gene drives. We highlight specific aspects of gene drive dynamics and the target populations that need further research.
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Affiliation(s)
- Sumit Dhole
- Department of Entomology and Plant Pathology, North Carolina State University, Raleigh, North Carolina 27695, USA
| | - Alun L Lloyd
- Biomathematics Graduate Program and Department of Mathematics, North Carolina State University, Raleigh, North Carolina 27695-8213, USA
- Genetic Engineering and Society Center, North Carolina State University, Raleigh, North Carolina 27695-7565, USA
| | - Fred Gould
- Department of Entomology and Plant Pathology, North Carolina State University, Raleigh, North Carolina 27695, USA
- Genetic Engineering and Society Center, North Carolina State University, Raleigh, North Carolina 27695-7565, USA
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13
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North AR, Burt A, Godfray HCJ. Modelling the suppression of a malaria vector using a CRISPR-Cas9 gene drive to reduce female fertility. BMC Biol 2020; 18:98. [PMID: 32782000 PMCID: PMC7422583 DOI: 10.1186/s12915-020-00834-z] [Citation(s) in RCA: 45] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2020] [Accepted: 07/22/2020] [Indexed: 12/21/2022] Open
Abstract
BACKGROUND Gene drives based on CRISPR-Cas9 technology are increasingly being considered as tools for reducing the capacity of mosquito populations to transmit malaria, and one of the most promising options is driving endonuclease genes that reduce the fertility of female mosquitoes. In particular, there is much interest in constructs that target the conserved mosquito doublesex (dsx) gene such that the emergence of functional drive-resistant alleles is unlikely. Proof of principle that these constructs can lead to substantial population suppression has been obtained in population cages, and they are being evaluated for use in sub-Saharan Africa. Here, we use simulation modelling to understand the factors affecting the spread of this type of gene drive over a one million-square kilometre area of West Africa containing substantial environmental and social heterogeneity. RESULTS We found that a driving endonuclease gene targeting female fertility could lead to substantial reductions in malaria vector populations on a regional scale. The exact level of suppression is influenced by additional fitness costs of the transgene such as the somatic expression of Cas9, and its deposition in sperm or eggs leading to damage to the zygote. In the absence of these costs, or of emergent drive-resistant alleles that restore female fertility, population suppression across the study area is predicted to stabilise at ~ 95% 4 years after releases commence. Small additional fitness costs do not greatly affect levels of suppression, though if the fertility of females whose offspring transmit the construct drops by more than ~ 40%, then population suppression is much less efficient. We show the suppression potential of a drive allele with high fitness costs can be enhanced by engineering it also to express male bias in the progeny of transgenic males. Irrespective of the strength of the drive allele, the spatial model predicts somewhat less suppression than equivalent non-spatial models, in particular in highly seasonal regions where dry season stochasticity reduces drive efficiency. We explored the robustness of these results to uncertainties in mosquito ecology, in particular their method of surviving the dry season and their dispersal rates. CONCLUSIONS The modelling presented here indicates that considerable suppression of vector populations can be achieved within a few years of using a female sterility gene drive, though the impact is likely to be heterogeneous in space and time.
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Affiliation(s)
- Ace R North
- Department of Zoology, University of Oxford, Oxford, UK.
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14
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Sougoufara S, Ottih EC, Tripet F. The need for new vector control approaches targeting outdoor biting Anopheline malaria vector communities. Parasit Vectors 2020; 13:295. [PMID: 32522290 PMCID: PMC7285743 DOI: 10.1186/s13071-020-04170-7] [Citation(s) in RCA: 67] [Impact Index Per Article: 16.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2020] [Accepted: 06/04/2020] [Indexed: 12/13/2022] Open
Abstract
Since the implementation of Roll Back Malaria, the widespread use of insecticide-treated nets (ITNs) and indoor residual spraying (IRS) is thought to have played a major part in the decrease in mortality and morbidity achieved in malaria-endemic regions. In the past decade, resistance to major classes of insecticides recommended for public health has spread across many malaria vector populations. Increasingly, malaria vectors are also showing changes in vector behaviour in response to current indoor chemical vector control interventions. Changes in the time of biting and proportion of indoor biting of major vectors, as well as changes in the species composition of mosquito communities threaten the progress made to control malaria transmission. Outdoor biting mosquito populations contribute to malaria transmission in many parts of sub-Saharan Africa and pose new challenges as they cannot be reliably monitored or controlled using conventional tools. Here, we review existing and novel approaches that may be used to target outdoor communities of malaria vectors. We conclude that scalable tools designed specifically for the control and monitoring of outdoor biting and resting malaria vectors with increasingly complex and dynamic responses to intensifying malaria control interventions are urgently needed. These are crucial for integrated vector management programmes designed to challenge current and future vector populations.
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Affiliation(s)
- Seynabou Sougoufara
- Centre of Applied Entomology and Parasitology, School of Life Sciences, Keele University, Staffordshire, UK
| | - Emmanuel Chinweuba Ottih
- Centre of Applied Entomology and Parasitology, School of Life Sciences, Keele University, Staffordshire, UK
| | - Frederic Tripet
- Centre of Applied Entomology and Parasitology, School of Life Sciences, Keele University, Staffordshire, UK
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15
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Besansky NJ. Malaria mosquitoes go with the flow. Nature 2019; 574:340-341. [DOI: 10.1038/d41586-019-02880-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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16
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Huestis DL, Dao A, Diallo M, Sanogo ZL, Samake D, Yaro AS, Ousman Y, Linton YM, Krishna A, Veru L, Krajacich BJ, Faiman R, Florio J, Chapman JW, Reynolds DR, Weetman D, Mitchell R, Donnelly MJ, Talamas E, Chamorro L, Strobach E, Lehmann T. Windborne long-distance migration of malaria mosquitoes in the Sahel. Nature 2019; 574:404-408. [PMID: 31578527 PMCID: PMC11095661 DOI: 10.1038/s41586-019-1622-4] [Citation(s) in RCA: 115] [Impact Index Per Article: 23.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2019] [Accepted: 09/06/2019] [Indexed: 11/09/2022]
Abstract
Over the past two decades efforts to control malaria have halved the number of cases globally, yet burdens remain high in much of Africa and the elimination of malaria has not been achieved even in areas where extreme reductions have been sustained, such as South Africa1,2. Studies seeking to understand the paradoxical persistence of malaria in areas in which surface water is absent for 3-8 months of the year have suggested that some species of Anopheles mosquito use long-distance migration3. Here we confirm this hypothesis through aerial sampling of mosquitoes at 40-290 m above ground level and provide-to our knowledge-the first evidence of windborne migration of African malaria vectors, and consequently of the pathogens that they transmit. Ten species, including the primary malaria vector Anopheles coluzzii, were identified among 235 anopheline mosquitoes that were captured during 617 nocturnal aerial collections in the Sahel of Mali. Notably, females accounted for more than 80% of all of the mosquitoes that we collected. Of these, 90% had taken a blood meal before their migration, which implies that pathogens are probably transported over long distances by migrating females. The likelihood of capturing Anopheles species increased with altitude (the height of the sampling panel above ground level) and during the wet seasons, but variation between years and localities was minimal. Simulated trajectories of mosquito flights indicated that there would be mean nightly displacements of up to 300 km for 9-h flight durations. Annually, the estimated numbers of mosquitoes at altitude that cross a 100-km line perpendicular to the prevailing wind direction included 81,000 Anopheles gambiae sensu stricto, 6 million A. coluzzii and 44 million Anopheles squamosus. These results provide compelling evidence that millions of malaria vectors that have previously fed on blood frequently migrate over hundreds of kilometres, and thus almost certainly spread malaria over these distances. The successful elimination of malaria may therefore depend on whether the sources of migrant vectors can be identified and controlled.
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Affiliation(s)
- Diana L Huestis
- Laboratory of Malaria and Vector Research, NIAID, NIH, Rockville, MD, USA
| | - Adama Dao
- Malaria Research and Training Center (MRTC), Faculty of Medicine, Pharmacy and Odonto-stomatology, University of Bamako, Bamako, Mali
| | - Moussa Diallo
- Malaria Research and Training Center (MRTC), Faculty of Medicine, Pharmacy and Odonto-stomatology, University of Bamako, Bamako, Mali
| | - Zana L Sanogo
- Malaria Research and Training Center (MRTC), Faculty of Medicine, Pharmacy and Odonto-stomatology, University of Bamako, Bamako, Mali
| | - Djibril Samake
- Malaria Research and Training Center (MRTC), Faculty of Medicine, Pharmacy and Odonto-stomatology, University of Bamako, Bamako, Mali
| | - Alpha S Yaro
- Malaria Research and Training Center (MRTC), Faculty of Medicine, Pharmacy and Odonto-stomatology, University of Bamako, Bamako, Mali
- Faculte des Sciences et Techniques, Universite des Sciences des Techniques et des Technologies de Bamako (FSTUSTTB), Bamako, Mali
| | - Yossi Ousman
- Malaria Research and Training Center (MRTC), Faculty of Medicine, Pharmacy and Odonto-stomatology, University of Bamako, Bamako, Mali
| | - Yvonne-Marie Linton
- Walter Reed Biosystematics Unit, Smithsonian Institution Museum Support Center, Suitland, MD, USA
- Department of Entomology, Smithsonian Institution, National Museum of Natural History, Washington, DC, USA
| | - Asha Krishna
- Laboratory of Malaria and Vector Research, NIAID, NIH, Rockville, MD, USA
| | - Laura Veru
- Laboratory of Malaria and Vector Research, NIAID, NIH, Rockville, MD, USA
| | | | - Roy Faiman
- Laboratory of Malaria and Vector Research, NIAID, NIH, Rockville, MD, USA
| | - Jenna Florio
- Laboratory of Malaria and Vector Research, NIAID, NIH, Rockville, MD, USA
| | - Jason W Chapman
- Centre for Ecology and Conservation, University of Exeter, Penryn, UK
- College of Plant Protection, Nanjing Agricultural University, Nanjing, China
- Environment and Sustainability Institute, University of Exeter, Penryn, UK
| | - Don R Reynolds
- Natural Resources Institute, University of Greenwich, Chatham, UK
- Rothamsted Research, Harpenden, UK
| | - David Weetman
- Department of Vector Biology, Liverpool School of Tropical Medicine, Liverpool, UK
| | - Reed Mitchell
- Walter Reed Biosystematics Unit, Smithsonian Institution Museum Support Center, Suitland, MD, USA
| | - Martin J Donnelly
- Department of Vector Biology, Liverpool School of Tropical Medicine, Liverpool, UK
| | - Elijah Talamas
- Systematic Entomology Laboratory - ARS, USDA, Smithsonian Institution National Museum of Natural History, Washington, DC, USA
- Florida Department of Agriculture and Consumer Services, Department of Plant Industry, Gainesville, FL, USA
| | - Lourdes Chamorro
- Department of Entomology, Smithsonian Institution, National Museum of Natural History, Washington, DC, USA
- Systematic Entomology Laboratory - ARS, USDA, Smithsonian Institution National Museum of Natural History, Washington, DC, USA
| | - Ehud Strobach
- Earth System Science Interdisciplinary Center, University of Maryland, College Park, MD, USA
- Global Modeling and Assimilation Office, NASA GSFC, Greenbelt, MD, USA
| | - Tovi Lehmann
- Laboratory of Malaria and Vector Research, NIAID, NIH, Rockville, MD, USA.
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North AR, Burt A, Godfray HCJ. Modelling the potential of genetic control of malaria mosquitoes at national scale. BMC Biol 2019; 17:26. [PMID: 30922310 PMCID: PMC6440076 DOI: 10.1186/s12915-019-0645-5] [Citation(s) in RCA: 64] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2019] [Accepted: 03/06/2019] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND The persistence of malaria in large parts of sub-Saharan Africa has motivated the development of novel tools to complement existing control programmes, including gene-drive technologies to modify mosquito vector populations. Here, we use a stochastic simulation model to explore the potential of using a driving-Y chromosome to suppress vector populations in a 106 km2 area of West Africa including all of Burkina Faso. RESULTS The consequence of driving-Y introductions is predicted to vary across the landscape, causing elimination of the target species in some regions and suppression in others. We explore how this variation is determined by environmental conditions, mosquito behaviour, and the properties of the gene-drive. Seasonality is particularly important, and we find population elimination is more likely in regions with mild dry seasons whereas suppression is more likely in regions with strong seasonality. CONCLUSIONS Despite the spatial heterogeneity, we suggest that repeated introductions of modified mosquitoes over a few years into a small fraction of human settlements may be sufficient to substantially reduce the overall number of mosquitoes across the entire geographic area.
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Affiliation(s)
- Ace R North
- Department of Zoology, University of Oxford, Oxford, UK.
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18
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Tandina F, Doumbo O, Yaro AS, Traoré SF, Parola P, Robert V. Mosquitoes (Diptera: Culicidae) and mosquito-borne diseases in Mali, West Africa. Parasit Vectors 2018; 11:467. [PMID: 30103823 PMCID: PMC6090629 DOI: 10.1186/s13071-018-3045-8] [Citation(s) in RCA: 40] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2018] [Accepted: 08/01/2018] [Indexed: 11/16/2022] Open
Abstract
Mosquito-borne diseases cause major human diseases in almost every part of the world. In West Africa, and notably in Mali, vector control measures help reduce the impact of mosquito-borne diseases, although malaria remains a threat to both morbidity and mortality. The most recent overview article on mosquitoes in Mali was published in 1961, with a total of 88 species. Our present review focuses on mosquitoes of medical importance among which the Anopheles vectors of Plasmodium and filaria, as well as the Culex and Aedes vectors of arboviruses. It aims to provide a concise update of the literature on Culicidae, covering the ecological areas in which the species are found but also the transmitted pathogens and recent innovative tools for vector surveys. This review highlights the recent introduction of invasive mosquito species, including Aedes albopictus and Culex neavei. The comprehensive list of mosquito species currently recorded includes 106 species (28 species of the Anophelinae and 78 species of the Culicinae). There are probable gaps in our knowledge concerning mosquitoes of the subfamily Culicinae and northern half of Mali because most studies have been carried out on the genus Anopheles and have taken place in the southern part of the country. It is hoped that this review may be useful to decision makers responsible for vector control strategies and to researchers for future surveys on mosquitoes, particularly the vectors of emerging arboviruses.
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Affiliation(s)
- Fatalmoudou Tandina
- Aix Marseille Univ, IRD, AP-HM, SSA, VITROME, IHU-Méditerranée Infection, Marseille, France
- Department of Epidemiology of Parasitic Diseases, Malaria Research and Training Center, Faculty of Sciences and Techniques, University of Science, Techniques and Technologies of Bamako, Bamako, Mali
| | - Ogobara Doumbo
- Department of Epidemiology of Parasitic Diseases, Malaria Research and Training Center, Faculty of Sciences and Techniques, University of Science, Techniques and Technologies of Bamako, Bamako, Mali
| | - Alpha Seydou Yaro
- Department of Epidemiology of Parasitic Diseases, Malaria Research and Training Center, Faculty of Sciences and Techniques, University of Science, Techniques and Technologies of Bamako, Bamako, Mali
| | - Sékou F. Traoré
- Department of Epidemiology of Parasitic Diseases, Malaria Research and Training Center, Faculty of Sciences and Techniques, University of Science, Techniques and Technologies of Bamako, Bamako, Mali
| | - Philippe Parola
- Aix Marseille Univ, IRD, AP-HM, SSA, VITROME, IHU-Méditerranée Infection, Marseille, France
| | - Vincent Robert
- MIVEGEC Unit, IRD-CNRS-Univ. Montpellier, Montpellier, France
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North AR, Godfray HCJ. Modelling the persistence of mosquito vectors of malaria in Burkina Faso. Malar J 2018; 17:140. [PMID: 29609598 PMCID: PMC5879775 DOI: 10.1186/s12936-018-2288-3] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2017] [Accepted: 03/21/2018] [Indexed: 11/26/2022] Open
Abstract
Background Populations of the Anopheles gambiae complex are found during the rainy season throughout West Africa, even in arid areas with long dry seasons during which mosquitoes appear to be absent. Several hypotheses have been proposed to explain this apparent paradox, including aestivation, dispersal between neighbouring settlements, and long distance migration using high-altitude wind currents. Methods An individual-based, spatially explicit model of mosquito populations was developed for a region of West Africa centred on, and including all of, Burkina Faso. Populations associated with human settlements were linked by dispersal and the model incorporated geospatial data on the distribution of settlements, water bodies and rainfall. Results Local dispersal (at rates consistent with experimental data) was necessary to explain observed patterns of rainy season populations across all of the simulation area, but by itself failed to account for the presence of populations in the arid North (the Sahel). The presence of rare dry-season larval sites could explain these northern populations, but seems inconsistent with field surveys. Aestivation by female mosquitoes explained rainy-season populations in all but the very sparsest and driest areas of human habitation, while long-distance migration based on annual wind patterns could account for all observed populations. Conclusions Modelling studies such as this can help assess the potential validity of different hypotheses and suggest priority areas for experimental study. In particular, the results highlight a shortage of empirical research on mosquito dispersal between neighbouring settlements, which may be critically important to the continued presence of many mosquito populations in West Africa. Further research that establishes the extent to which mosquitoes aestivate, and migrate using high altitude winds, is also much needed to understand Sahelian mosquito populations. Electronic supplementary material The online version of this article (10.1186/s12936-018-2288-3) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Ace R North
- Department of Zoology, University of Oxford, Woodstock Road, Oxford, OX2 6GG, UK.
| | - H Charles J Godfray
- Department of Zoology, University of Oxford, Woodstock Road, Oxford, OX2 6GG, UK
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Lehmann T, Weetman D, Huestis DL, Yaro AS, Kassogue Y, Diallo M, Donnelly MJ, Dao A. Tracing the origin of the early wet-season Anopheles coluzzii in the Sahel. Evol Appl 2017; 10:704-717. [PMID: 28717390 PMCID: PMC5511357 DOI: 10.1111/eva.12486] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2016] [Accepted: 02/24/2017] [Indexed: 11/29/2022] Open
Abstract
In arid environments, the source of the malaria mosquito populations that re‐establish soon after first rains remains a puzzle and alternative explanations have been proposed. Using genetic data, we evaluated whether the early rainy season (RS) population of Anopheles coluzzii is descended from the preceding late RS generation at the same locality, consistent with dry season (DS) dormancy (aestivation), or from migrants from distant locations. Distinct predictions derived from these two hypotheses were assessed, based on variation in 738 SNPs in eleven A. coluzzii samples, including seven samples spanning 2 years in a Sahelian village. As predicted by the “local origin under aestivation hypothesis,” temporal samples from the late RS and those collected after the first rain of the following RS were clustered together, while larger genetic distances were found among samples spanning the RS. Likewise, multilocus genotype composition of samples from the end of the RS was similar across samples until the following RS, unlike samples that spanned the RS. Consistent with reproductive arrest during the DS, no genetic drift was detected between samples taken over that period, despite encompassing extreme population minima, whereas it was detected between samples spanning the RS. Accordingly, the variance in allele frequency increased with time over the RS, but not over the DS. However, not all the results agreed with aestivation. Large genetic distances separated samples taken a year apart, and during the first year, within‐sample genetic diversity declined and increased back during the late RS, suggesting a bottleneck followed by migration. The decline of genetic diversity followed by a mass distribution of insecticide‐treated nets was accompanied by a reduced mosquito density and a rise in the mutation conferring resistance to pyrethroids, indicating a bottleneck due to insecticidal selection. Overall, our results support aestivation in A. coluzzii during the DS that is accompanied by long‐distance migration in the late RS.
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Affiliation(s)
- Tovi Lehmann
- Laboratory of Malaria and Vector Research NIAID, NIH Rockville MD USA
| | - David Weetman
- Department of Vector Biology Liverpool School of Tropical Medicine Liverpool UK
| | - Diana L Huestis
- Laboratory of Malaria and Vector Research NIAID, NIH Rockville MD USA
| | - Alpha S Yaro
- Malaria Research and Training Center (MRTC) Faculty of Medicine, Pharmacy and Odonto-stomatology Bamako Mali
| | - Yaya Kassogue
- Malaria Research and Training Center (MRTC) Faculty of Medicine, Pharmacy and Odonto-stomatology Bamako Mali
| | - Moussa Diallo
- Malaria Research and Training Center (MRTC) Faculty of Medicine, Pharmacy and Odonto-stomatology Bamako Mali
| | - Martin J Donnelly
- Department of Vector Biology Liverpool School of Tropical Medicine Liverpool UK
| | - Adama Dao
- Malaria Research and Training Center (MRTC) Faculty of Medicine, Pharmacy and Odonto-stomatology Bamako Mali
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