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McCann RS, Courneya JP, Donnelly M, Laufer MK, Mzilahowa T, Stewart K, Miles A, Takala-Harrison S, O'Connor TD. Variation in spatial population structure in the Anopheles gambiae species complex. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.05.26.595955. [PMID: 38853983 PMCID: PMC11160690 DOI: 10.1101/2024.05.26.595955] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2024]
Abstract
Anopheles gambiae, Anopheles coluzzii , and Anopheles arabiensis are three of the most widespread vectors of malaria parasites, with geographical ranges stretching across wide swaths of Africa. Understanding the population structure of these closely related species, including the extent to which populations are connected by gene flow, is essential for understanding how vector control implemented in one location might indirectly affect vector populations in other locations. Here, we assessed the population structure of each species based on whole-genome sequences from the third phase of the Anopheles gambiae 1000 Genomes Project. The data set included single nucleotide polymorphisms from whole genomes of 2,242 individual mosquitoes sampled from 119 locations across 19 African countries. We found that A. gambiae sampled from several countries in West and Central Africa showed low genetic differentiation from each other according to principal components analysis (PCA) and ADMIXTURE modeling. Using Estimated Effective Migration Surfaces (EEMS), we showed that this low genetic differentiation indicates high effective migration rates for A. gambiae across this region. Outside of this region, we found six groups of sampling locations from Central, East, and Southern Africa for which A. gambiae showed higher genetic differentiation, and lower effective migration rates, between each other and the West/Central Africa group. These results indicate that the barriers to and corridors for migration between populations of A. gambiae differ across the geographical range of this malaria vector species. Using the same methods, we found higher genetic differentiation and lower migration rates between populations of A. coluzzii in West and Central Africa than for A. gambiae in the same region. On the other hand, we found lower genetic differentiation and higher migration rates between populations of A. arabiensis in Tanzania, compared to A. gambiae in the same region. These differences between A. gambiae, A. coluzzii , and A. arabiensis indicate that migration barriers and corridors may vary between species, even for very closely related species. Overall, our results demonstrate that migration rates vary both between and within species of Anopheles mosquitoes, presumably based on species-specific responses to the ecological or environmental conditions that may impede or facilitate migration, and the geographical patterns of these conditions across the landscape. Together with previous findings, this study provides robust evidence that migration rates between populations of malaria vectors depend on the ecological context, which should be considered when planning surveillance of vector populations, monitoring for insecticide resistance, and evaluating interventions.
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Das S, Máquina M, Phillips K, Cuamba N, Marrenjo D, Saúte F, Paaijmans KP, Huijben S. Fine-scale spatial distribution of deltamethrin resistance and population structure of Anopheles funestus and Anopheles arabiensis populations in Southern Mozambique. Malar J 2023; 22:94. [PMID: 36915131 PMCID: PMC10010967 DOI: 10.1186/s12936-023-04522-5] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2022] [Accepted: 03/03/2023] [Indexed: 03/16/2023] Open
Abstract
BACKGROUND Insecticide resistance in malaria vectors can be spatially highly heterogeneous, yet population structure analyses frequently find relatively high levels of gene flow among mosquito populations. Few studies have contemporaneously assessed phenotypic, genotypic and population structure analysis on mosquito populations and none at fine geographical scales. In this study, genetic diversity, population structure, and insecticide resistance profiles of Anopheles funestus and Anopheles arabiensis were examined across mosquito populations from and within neighbouring villages. METHODS Mosquitoes were collected from 11 towns in southern Mozambique, as well as from different neighbourhoods within the town of Palmeira, during the peak malaria transmission season in 2016. CDC bottle bioassay and PCR assays were performed with Anopheles mosquitoes at each site to determine phenotypic and molecular insecticide resistance profiles, respectively. Microsatellite analysis was conducted on a subsample of mosquitoes to estimate genetic diversity and population structure. RESULTS Phenotypic insecticide resistance to deltamethrin was observed in An. funestus sensu stricto (s.s.) throughout the area, though a high level of mortality variation was seen. However, 98% of An. funestus s.s. were CYP6P9a homozygous resistant. An. arabiensis was phenotypically susceptible to deltamethrin and 99% were kdr homozygous susceptible. Both Anopheles species exhibited high allelic richness and heterozygosity. Significant deviations from Hardy-Weinberg equilibrium were observed, and high linkage disequilibrium was seen for An. funestus s.s., supporting population subdivision. However, the FST values were low for both anophelines (- 0.00457 to 0.04213), Nm values were high (9.4-71.8 migrants per generation), AMOVA results showed almost 100% genetic variation among and within individuals, and Structure analysis showed no clustering of An. funestus s.s. and An. arabiensis populations. These results suggest high gene flow among mosquito populations. CONCLUSION Despite a relatively high level of phenotypic variation in the An. funestus population, molecular analysis shows the population is admixed. These data indicate that CYP6P9a resistance markers do not capture all phenotypic variation in the area, but also that resistance genes of high impact are likely to easily spread in the area. Conversely, other strategies, such as transgenic mosquito release programmes will likely not face challenges in this locality.
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Affiliation(s)
- Smita Das
- The Center for Evolution & Medicine, School of Life Sciences, Arizona State University, Tempe, AZ, USA
- PATH, Seattle, WA, USA
| | - Mara Máquina
- Centro de Investigação em Saúde de Manhiça (CISM), Fundação Manhiça, Manhica, Mozambique
| | - Keeley Phillips
- The Center for Evolution & Medicine, School of Life Sciences, Arizona State University, Tempe, AZ, USA
| | - Nelson Cuamba
- Programa Nacional de Controlo da Malária, Ministério da Saúde, Maputo, Mozambique
- PMI VectorLink Project, Abt Associates Inc., Maputo, Mozambique
| | - Dulcisaria Marrenjo
- Programa Nacional de Controlo da Malária, Ministério da Saúde, Maputo, Mozambique
| | - Francisco Saúte
- Centro de Investigação em Saúde de Manhiça (CISM), Fundação Manhiça, Manhica, Mozambique
| | - Krijn P Paaijmans
- The Center for Evolution & Medicine, School of Life Sciences, Arizona State University, Tempe, AZ, USA
- Simon A. Levin Mathematical, Computational and Modeling Sciences Center, Arizona State University, Tempe, AZ, USA
- The Biodesign Center for Immunotherapy, Vaccines and Virotherapy, Arizona State University, Tempe, AZ, USA
- ISGlobal, Barcelona, Spain
| | - Silvie Huijben
- The Center for Evolution & Medicine, School of Life Sciences, Arizona State University, Tempe, AZ, USA.
- Simon A. Levin Mathematical, Computational and Modeling Sciences Center, Arizona State University, Tempe, AZ, USA.
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Bergey CM, Lukindu M, Wiltshire RM, Fontaine MC, Kayondo JK, Besansky NJ. Assessing connectivity despite high diversity in island populations of a malaria mosquito. Evol Appl 2020; 13:417-431. [PMID: 31993086 PMCID: PMC6976967 DOI: 10.1111/eva.12878] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2019] [Revised: 08/28/2019] [Accepted: 09/27/2019] [Indexed: 12/14/2022] Open
Abstract
Documenting isolation is notoriously difficult for species with vast polymorphic populations. High proportions of shared variation impede estimation of connectivity, even despite leveraging information from many genetic markers. We overcome these impediments by combining classical analysis of neutral variation with assays of the structure of selected variation, demonstrated using populations of the principal African malaria vector Anopheles gambiae. Accurate estimation of mosquito migration is crucial for efforts to combat malaria. Modeling and cage experiments suggest that mosquito gene drive systems will enable malaria eradication, but establishing safety and efficacy requires identification of isolated populations in which to conduct field testing. We assess Lake Victoria islands as candidate sites, finding one island 30 km offshore is as differentiated from mainland samples as populations from across the continent. Collectively, our results suggest sufficient contemporary isolation of these islands to warrant consideration as field-testing locations and illustrate shared adaptive variation as a useful proxy for connectivity in highly polymorphic species.
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Affiliation(s)
- Christina M. Bergey
- Department of Biological SciencesUniversity of Notre DameNotre DameINUSA
- Eck Institute for Global HealthUniversity of Notre DameNotre DameINUSA
- Department of GeneticsRutgers UniversityPiscatawayNJUSA
- Departments of Anthropology and BiologyPennsylvania State UniversityUniversity ParkPAUSA
| | - Martin Lukindu
- Department of Biological SciencesUniversity of Notre DameNotre DameINUSA
- Eck Institute for Global HealthUniversity of Notre DameNotre DameINUSA
| | - Rachel M. Wiltshire
- Department of Biological SciencesUniversity of Notre DameNotre DameINUSA
- Eck Institute for Global HealthUniversity of Notre DameNotre DameINUSA
| | - Michael C. Fontaine
- Groningen Institute for Evolutionary Life Sciences (GELIFES)University of GroningenGroningenThe Netherlands
- MIVEGECIRDCNRSUniversity of MontpellierMontpellierFrance
| | | | - Nora J. Besansky
- Department of Biological SciencesUniversity of Notre DameNotre DameINUSA
- Eck Institute for Global HealthUniversity of Notre DameNotre DameINUSA
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Matiya DJ, Philbert AB, Kidima W, Matowo JJ. Dynamics and monitoring of insecticide resistance in malaria vectors across mainland Tanzania from 1997 to 2017: a systematic review. Malar J 2019; 18:102. [PMID: 30914051 PMCID: PMC6434877 DOI: 10.1186/s12936-019-2738-6] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2018] [Accepted: 03/20/2019] [Indexed: 11/22/2022] Open
Abstract
Background Malaria still claims substantial lives of individuals in Tanzania. Insecticide-treated nets (ITNs) and indoor residual spray (IRS) are used as major malaria vector control tools. These tools are facing great challenges from the rapid escalating insecticide resistance in malaria vector populations. This review presents the information on the dynamics and monitoring of insecticide resistance in malaria vectors in mainland Tanzania since 1997. The information is important to policy-makers and other vector control stakeholders to reflect and formulate new resistance management plans in the country. Methods Reviewed articles on susceptibility and mechanisms of resistance in malaria vectors to insecticides across mainland Tanzania were systematically searched from the following databases: PubMed, Google scholar, HINARI and AGORA. The inclusion criteria were articles published between 2000 and 2017, reporting susceptibility of malaria vectors to insecticides, mechanisms of resistance in the mainland Tanzania, involving field collected adult mosquitoes, and mosquitoes raised from the field collected larvae. Exclusion criteria were articles reporting insecticide resistance in larval bio-assays, laboratory strains, and unpublished data. Reviewed information include year of study, malaria vectors, insecticides, and study sites. This information was entered in the excel sheet and analysed. Results A total of 30 articles met the selection criteria. The rapid increase of insecticide resistance in the malaria vectors across the country was reported since year 2006 onwards. Insecticide resistance in Anopheles gambiae sensu lato (s.l.) was detected in at least one compound in each class of all recommended insecticide classes. However, the Anopheles funestus s.l. is highly resistant to pyrethroids and DDT. Knockdown resistance (kdr) mechanism in An. gambiae s.l. is widely studied in the country. Biochemical resistance by detoxification enzymes (P450s, NSE and GSTs) in An. gambiae s.l. was also recorded. Numerous P450s genes associated with metabolic resistance were over transcribed in An. gambiae s.l. collected from agricultural areas. However, no study has reported mechanisms of insecticide resistance in the An. funestus s.l. in the country. Conclusion This review has shown the dynamics and monitoring of insecticide resistance in malaria vector populations across mainland Tanzanian. This highlights the need for devising improved control approaches of the malaria vectors in the country.
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Affiliation(s)
- Deokary Joseph Matiya
- Dar es Salaam University College of Education (DUCE), P.O. Box 2329, Dar es Salaam, Tanzania. .,University of Dar es Salaam (UDSM), P.O. Box 35064, Dar es Salaam, Tanzania.
| | - Anitha B Philbert
- University of Dar es Salaam (UDSM), P.O. Box 35064, Dar es Salaam, Tanzania
| | - Winifrida Kidima
- University of Dar es Salaam (UDSM), P.O. Box 35064, Dar es Salaam, Tanzania
| | - Johnson J Matowo
- Kilimanjaro Christian Medical University College (KCMUCo), P.O. Box 2240, Moshi, Tanzania
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James S, Collins FH, Welkhoff PA, Emerson C, Godfray HCJ, Gottlieb M, Greenwood B, Lindsay SW, Mbogo CM, Okumu FO, Quemada H, Savadogo M, Singh JA, Tountas KH, Touré YT. Pathway to Deployment of Gene Drive Mosquitoes as a Potential Biocontrol Tool for Elimination of Malaria in Sub-Saharan Africa: Recommendations of a Scientific Working Group †. Am J Trop Med Hyg 2018; 98:1-49. [PMID: 29882508 PMCID: PMC5993454 DOI: 10.4269/ajtmh.18-0083] [Citation(s) in RCA: 124] [Impact Index Per Article: 20.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2018] [Accepted: 04/04/2018] [Indexed: 12/22/2022] Open
Abstract
Gene drive technology offers the promise for a high-impact, cost-effective, and durable method to control malaria transmission that would make a significant contribution to elimination. Gene drive systems, such as those based on clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR associated protein, have the potential to spread beneficial traits through interbreeding populations of malaria mosquitoes. However, the characteristics of this technology have raised concerns that necessitate careful consideration of the product development pathway. A multidisciplinary working group considered the implications of low-threshold gene drive systems on the development pathway described in the World Health Organization Guidance Framework for testing genetically modified (GM) mosquitoes, focusing on reduction of malaria transmission by Anopheles gambiae s.l. mosquitoes in Africa as a case study. The group developed recommendations for the safe and ethical testing of gene drive mosquitoes, drawing on prior experience with other vector control tools, GM organisms, and biocontrol agents. These recommendations are organized according to a testing plan that seeks to maximize safety by incrementally increasing the degree of human and environmental exposure to the investigational product. As with biocontrol agents, emphasis is placed on safety evaluation at the end of physically confined laboratory testing as a major decision point for whether to enter field testing. Progression through the testing pathway is based on fulfillment of safety and efficacy criteria, and is subject to regulatory and ethical approvals, as well as social acceptance. The working group identified several resources that were considered important to support responsible field testing of gene drive mosquitoes.
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Affiliation(s)
- Stephanie James
- Foundation for the National Institutes of Health, Bethesda, Maryland
| | | | | | | | | | - Michael Gottlieb
- Foundation for the National Institutes of Health, Bethesda, Maryland
| | - Brian Greenwood
- London School of Hygiene & Tropical Medicine, London, United Kingdom
| | | | | | - Fredros O. Okumu
- Ifakara Health Institute, Ifakara, Tanzania
- University of Glasgow, Glasgow, Scotland
- University of the Witwatersrand, Johannesburg, South Africa
| | - Hector Quemada
- Donald Danforth Plant Science Center, Saint Louis, Missouri
| | - Moussa Savadogo
- New Partnership for Africa’s Development, Ouagadougou, Burkina Faso
| | - Jerome A. Singh
- Centre for the AIDS Programme of Research in South Africa, Durban, KwaZulu-Natal, South Africa
| | - Karen H. Tountas
- Foundation for the National Institutes of Health, Bethesda, Maryland
| | - Yeya T. Touré
- University of Sciences, Techniques and Technologies of Bamako, Bamako, Mali
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Lukindu M, Bergey CM, Wiltshire RM, Small ST, Bourke BP, Kayondo JK, Besansky NJ. Spatio-temporal genetic structure of Anopheles gambiae in the Northwestern Lake Victoria Basin, Uganda: implications for genetic control trials in malaria endemic regions. Parasit Vectors 2018; 11:246. [PMID: 29661226 PMCID: PMC5902950 DOI: 10.1186/s13071-018-2826-4] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2018] [Accepted: 03/28/2018] [Indexed: 11/30/2022] Open
Abstract
Background Understanding population genetic structure in the malaria vector Anopheles gambiae (s.s.) is crucial to inform genetic control and manage insecticide resistance. Unfortunately, species characteristics such as high nucleotide diversity, large effective population size, recent range expansion, and high dispersal ability complicate the inference of genetic structure across its range in sub-Saharan Africa. The ocean, along with the Great Rift Valley, is one of the few recognized barriers to gene flow in this species, but the effect of inland lakes, which could be useful sites for initial testing of genetic control strategies, is relatively understudied. Here we examine Lake Victoria as a barrier between the Ugandan mainland and the Ssese Islands, which lie up to 60 km offshore. We use mitochondrial DNA (mtDNA) from populations sampled in 2002, 2012 and 2015, and perform Bayesian cluster analysis on mtDNA combined with microsatellite data previously generated from the same 2002 mosquito DNA samples. Results Hierarchical analysis of molecular variance and Bayesian clustering support significant differentiation between the mainland and lacustrine islands. In an mtDNA haplotype network constructed from this and previous data, haplotypes are shared even between localities separated by the Rift Valley, a result that more likely reflects retention of shared ancestral polymorphism than contemporary gene flow. Conclusions The relative genetic isolation of An. gambiae on the Ssese Islands, their small size, level terrain and ease of access from the mainland, the relative simplicity of the vectorial system, and the prevalence of malaria, are all attributes that recommend these islands as possible sites for the testing of genetic control strategies.
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Affiliation(s)
- Martin Lukindu
- Department of Biological Sciences and Eck Institute for Global Health, University of Notre Dame, Notre Dame, IN, 46556, USA
| | - Christina M Bergey
- Department of Biological Sciences and Eck Institute for Global Health, University of Notre Dame, Notre Dame, IN, 46556, USA
| | - Rachel M Wiltshire
- Department of Biological Sciences and Eck Institute for Global Health, University of Notre Dame, Notre Dame, IN, 46556, USA
| | - Scott T Small
- Department of Biological Sciences and Eck Institute for Global Health, University of Notre Dame, Notre Dame, IN, 46556, USA
| | - Brian P Bourke
- Department of Biological Sciences and Eck Institute for Global Health, University of Notre Dame, Notre Dame, IN, 46556, USA
| | - Jonathan K Kayondo
- Department of Entomology, Uganda Virus Research Institute (UVRI), Entebbe, Uganda
| | - Nora J Besansky
- Department of Biological Sciences and Eck Institute for Global Health, University of Notre Dame, Notre Dame, IN, 46556, USA.
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Ranford-Cartwright LC, McGeechan S, Inch D, Smart G, Richterová L, Mwangi JM. Characterisation of Species and Diversity of Anopheles gambiae Keele Colony. PLoS One 2016; 11:e0168999. [PMID: 28033418 PMCID: PMC5199079 DOI: 10.1371/journal.pone.0168999] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2016] [Accepted: 12/09/2016] [Indexed: 11/18/2022] Open
Abstract
Anopheles gambiae sensu stricto was recently reclassified as two species, An. coluzzii and An. gambiae s.s., in wild-caught mosquitoes, on the basis of the molecular form, denoted M or S, of a marker on the X chromosome. The An. gambiae Keele line is an outbred laboratory colony strain that was developed around 12 years ago by crosses between mosquitoes from 4 existing An. gambiae colonies. Laboratory colonies of mosquitoes often have limited genetic diversity because of small starting populations (founder effect) and subsequent fluctuations in colony size. Here we describe the characterisation of the chromosomal form(s) present in the Keele line, and investigate the diversity present in the colony using microsatellite markers on chromosome 3. We also characterise the large 2La inversion on chromosome 2. The results indicate that only the M-form of the chromosome X marker is present in the Keele colony, which was unexpected given that 3 of the 4 parent colonies were probably S-form. Levels of diversity were relatively high, as indicated by a mean number of microsatellite alleles of 6.25 across 4 microsatellites, in at least 25 mosquitoes. Both karyotypes of the inversion on chromosome 2 (2La/2L+a) were found to be present at approximately equal proportions. The Keele colony has a mixed M- and S-form origin, and in common with the PEST strain, we propose continuing to denote it as an An. gambiae s.s. line.
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Affiliation(s)
- Lisa C Ranford-Cartwright
- Institute of Infection, Immunity and Inflammation, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, Scotland, United Kingdom
| | - Sion McGeechan
- Institute of Infection, Immunity and Inflammation, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, Scotland, United Kingdom
| | - Donald Inch
- Institute of Infection, Immunity and Inflammation, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, Scotland, United Kingdom
| | - Graeme Smart
- Institute of Infection, Immunity and Inflammation, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, Scotland, United Kingdom
| | - Lenka Richterová
- Institute of Infection, Immunity and Inflammation, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, Scotland, United Kingdom
| | - Jonathan M Mwangi
- Institute of Infection, Immunity and Inflammation, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, Scotland, United Kingdom
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Maliti DV, Marsden CD, Main BJ, Govella NJ, Yamasaki Y, Collier TC, Kreppel K, Chiu JC, Lanzaro GC, Ferguson HM, Lee Y. Investigating associations between biting time in the malaria vector Anopheles arabiensis Patton and single nucleotide polymorphisms in circadian clock genes: support for sub-structure among An. arabiensis in the Kilombero valley of Tanzania. Parasit Vectors 2016; 9:109. [PMID: 26920563 PMCID: PMC4769569 DOI: 10.1186/s13071-016-1394-8] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2015] [Accepted: 02/18/2016] [Indexed: 12/31/2022] Open
Abstract
Background There is growing evidence that the widespread use of Long-Lasting Insecticidal Nets (LLINs) is prompting malaria vectors to shift their biting towards times and places where people are not protected, such as earlier in the evening and/or outdoors. It is uncertain whether these behavioural shifts are due to phenotypic plasticity and/or ecological changes within vector communities that favour more exophilic species, or involve genetic factors within vector species to limit their contact with LLINs. Possibly variation in the time and location of mosquito biting has a genetic basis, but as yet this phenomenon has received little investigation. Here we used a candidate gene approach to investigate whether polymorphisms in selected circadian clock genes could explain variation in the time and location of feeding (indoors versus outside) within a natural population of the major African malaria vector Anopheles arabiensis. Methods Host-seeking An. arabiensis were collected from two villages (Lupiro and Sagamaganga) in Tanzania by Human Landing Catch (HLC) technique. Mosquitoes were classified into phenotypes of “early” (7 pm–10 pm) or “late” biting (4 am –7 am), and host-seeking indoors or outdoors. In these samples we genotyped 34 coding SNPs in 8 clock genes (PER, TIM, CLK, CYC, PDP1, VRI, CRY1, and CRY2), and tested for associations between these SNPs and biting phenotypes. SNPs in 8 mitochondrial genes (ATP6, ATP8, COX1, COX2, COX3, ND3, ND5 and CYTB) were also genotyped to test population subdivision within An. arabiensis. Results The candidate clock genes exhibited polymorphism within An. arabiensis, but it was unrelated to variation in the timing and location of their biting activity. However, there was evidence of strong genetic structure within An. arabiensis populations in association with the TIM, which was unrelated to geographic distance. Substructure within An. arabiensis was also detected using mitochondrial markers. Conclusions The variable timing and location of biting in An. arabiensis could not be linked to candidate clock genes that are known to influence behaviour in other Diptera. This finding does not rule out the possibility of a genetic basis to biting behaviour in this malaria vector, but suggests these are complex phenotypes that require more intensive ecological, neuronal and genomic analyses to understand. Electronic supplementary material The online version of this article (doi:10.1186/s13071-016-1394-8) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Deodatus Vincent Maliti
- Environmental Health and Ecological Sciences Thematic Group, Ifakara Health Institute, Ifakara, Morogoro, Tanzania. .,Nelson Mandela African Institute of Science and Technology Tanzania, School of Life Sciences, Arusha, Tanzania. .,Institute of Biodiversity Animal Health and Comparative Medicine, University of Glasgow, Glasgow, Lancashire, UK.
| | - C D Marsden
- School of Veterinary Medicine, University of California Davis, Davis, CA, USA.
| | - B J Main
- School of Veterinary Medicine, University of California Davis, Davis, CA, USA.
| | - N J Govella
- Environmental Health and Ecological Sciences Thematic Group, Ifakara Health Institute, Ifakara, Morogoro, Tanzania.
| | - Y Yamasaki
- School of Veterinary Medicine, University of California Davis, Davis, CA, USA.
| | - T C Collier
- School of Veterinary Medicine, University of California Davis, Davis, CA, USA.
| | - K Kreppel
- Institute of Biodiversity Animal Health and Comparative Medicine, University of Glasgow, Glasgow, Lancashire, UK.
| | - J C Chiu
- Department of Entomology and Nematology, University of California Davis, Davis, CA, USA.
| | - G C Lanzaro
- School of Veterinary Medicine, University of California Davis, Davis, CA, USA.
| | - H M Ferguson
- Department of Entomology and Nematology, University of California Davis, Davis, CA, USA.
| | - Y Lee
- School of Veterinary Medicine, University of California Davis, Davis, CA, USA.
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Briët OJT, Huho BJ, Gimnig JE, Bayoh N, Seyoum A, Sikaala CH, Govella N, Diallo DA, Abdullah S, Smith TA, Killeen GF. Applications and limitations of Centers for Disease Control and Prevention miniature light traps for measuring biting densities of African malaria vector populations: a pooled-analysis of 13 comparisons with human landing catches. Malar J 2015; 14:247. [PMID: 26082036 PMCID: PMC4470360 DOI: 10.1186/s12936-015-0761-9] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2015] [Accepted: 06/02/2015] [Indexed: 11/20/2022] Open
Abstract
Background Measurement of densities of host-seeking malaria vectors is important for estimating levels of disease transmission, for appropriately allocating interventions, and for quantifying their impact. The gold standard for estimating mosquito—human contact rates is the human landing catch (HLC), where human volunteers catch mosquitoes that land on their exposed body parts. This approach necessitates exposure to potentially infectious mosquitoes, and is very labour intensive. There are several safer and less labour-intensive methods, with Centers for Disease Control light traps (LT) placed indoors near occupied bed nets being the most widely used. Methods This paper presents analyses of 13 studies with paired mosquito collections of LT and HLC to evaluate these methods for their consistency in sampling indoor-feeding mosquitoes belonging to the two major taxa of malaria vectors across Africa, the Anopheles gambiae sensu lato complex and the Anopheles funestus s.l. group. Both overall and study-specific sampling efficiencies of LT compared with HLC were computed, and regression methods that allow for the substantial variations in mosquito counts made by either method were used to test whether the sampling efficacy varies with mosquito density. Results Generally, LT were able to collect similar numbers of mosquitoes to the HLC indoors, although the relative sampling efficacy, measured by the ratio of LT:HLC varied considerably between studies. The overall best estimate for An. gambiae s.l. was 1.06 (95% credible interval: 0.68–1.64) and for An. funestus s.l. was 1.37 (0.70–2.68). Local calibration exercises are not reproducible, since only in a few studies did LT sample proportionally to HLC, and there was no geographical pattern or consistent trend with average density in the tendency for LT to either under- or over-sample. Conclusions LT are a crude tool at best, but are relatively easy to deploy on a large scale. Spatial and temporal variation in mosquito densities and human malaria transmission exposure span several orders of magnitude, compared to which the inconsistencies of LT are relatively small. LT, therefore, remain an invaluable and safe alternative to HLC for measuring indoor malaria transmission exposure in Africa. Electronic supplementary material The online version of this article (doi:10.1186/s12936-015-0761-9) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Olivier J T Briët
- Department of Epidemiology and Public Health, Swiss Tropical and Public Health Institute, Socinstrasse 57, 4002, Basel, Switzerland. .,University of Basel, Petersplatz 1, Basel, 4003, Switzerland.
| | - Bernadette J Huho
- Department of Epidemiology and Public Health, Swiss Tropical and Public Health Institute, Socinstrasse 57, 4002, Basel, Switzerland. .,University of Basel, Petersplatz 1, Basel, 4003, Switzerland. .,Ifakara Health Institute, PO Box 78373, Dar es Salaam, United Republic of Tanzania.
| | - John E Gimnig
- Centre for Global Health Research, Kenya Medical Research Institute, PO Box 1578, Kisumu, Kenya. .,Division of Parasitic Diseases, Centers for Disease Control and Prevention, Atlanta, 4770 Buford Highway, Mailstop F-42, Atlanta, GA, 30341, USA.
| | - Nabie Bayoh
- Centre for Global Health Research, Kenya Medical Research Institute, PO Box 1578, Kisumu, Kenya. .,Centers for Disease Control and Prevention, PO Box 1578, Kisumu, Kenya.
| | - Aklilu Seyoum
- Vector Biology Department, Liverpool School of Tropical Medicine, Pembroke Place, Liverpool, L3 5QA, UK.
| | - Chadwick H Sikaala
- Vector Biology Department, Liverpool School of Tropical Medicine, Pembroke Place, Liverpool, L3 5QA, UK. .,National Malaria Control Centre, Chainama Hospital College Grounds, Off Great East Road, PO Box 32509, Lusaka, Zambia.
| | - Nicodem Govella
- Ifakara Health Institute, PO Box 78373, Dar es Salaam, United Republic of Tanzania.
| | - Diadier A Diallo
- Centre National de Recherche et de Formation sur le Paludisme (CNRFP), 01 BP 2208, Ouagadougou 01, Ouagadougou, Burkina Faso.
| | - Salim Abdullah
- Ifakara Health Institute, PO Box 78373, Dar es Salaam, United Republic of Tanzania.
| | - Thomas A Smith
- Department of Epidemiology and Public Health, Swiss Tropical and Public Health Institute, Socinstrasse 57, 4002, Basel, Switzerland. .,University of Basel, Petersplatz 1, Basel, 4003, Switzerland.
| | - Gerry F Killeen
- Ifakara Health Institute, PO Box 78373, Dar es Salaam, United Republic of Tanzania. .,Vector Biology Department, Liverpool School of Tropical Medicine, Pembroke Place, Liverpool, L3 5QA, UK.
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