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Koekemoer LL, Spillings BL, Christian RN, Lo TCM, Kaiser ML, Norton RA, Oliver SV, Choi KS, Brooke BD, Hunt RH, Coetzee M. Multiple Insecticide Resistance inAnopheles gambiae(Diptera: Culicidae) from Pointe Noire, Republic of the Congo. Vector Borne Zoonotic Dis 2011; 11:1193-200. [DOI: 10.1089/vbz.2010.0192] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Affiliation(s)
- Lizette L. Koekemoer
- Malaria Entomology Research Unit, Faculty of Health Sciences, School of Pathology, University of the Witwatersrand, Johannesburg, South Africa
- Vector Control Reference Unit, National Institute for Communicable Diseases, National Health Laboratory Service (NHLS), Johannesburg, South Africa
| | - Belinda L. Spillings
- Malaria Entomology Research Unit, Faculty of Health Sciences, School of Pathology, University of the Witwatersrand, Johannesburg, South Africa
- Vector Control Reference Unit, National Institute for Communicable Diseases, National Health Laboratory Service (NHLS), Johannesburg, South Africa
| | - Riann N. Christian
- Malaria Entomology Research Unit, Faculty of Health Sciences, School of Pathology, University of the Witwatersrand, Johannesburg, South Africa
- Vector Control Reference Unit, National Institute for Communicable Diseases, National Health Laboratory Service (NHLS), Johannesburg, South Africa
| | - Te-Chang M. Lo
- Malaria Entomology Research Unit, Faculty of Health Sciences, School of Pathology, University of the Witwatersrand, Johannesburg, South Africa
- Vector Control Reference Unit, National Institute for Communicable Diseases, National Health Laboratory Service (NHLS), Johannesburg, South Africa
| | - Maria L. Kaiser
- Malaria Entomology Research Unit, Faculty of Health Sciences, School of Pathology, University of the Witwatersrand, Johannesburg, South Africa
- Vector Control Reference Unit, National Institute for Communicable Diseases, National Health Laboratory Service (NHLS), Johannesburg, South Africa
| | - Ryan A.I. Norton
- Malaria Entomology Research Unit, Faculty of Health Sciences, School of Pathology, University of the Witwatersrand, Johannesburg, South Africa
- Vector Control Reference Unit, National Institute for Communicable Diseases, National Health Laboratory Service (NHLS), Johannesburg, South Africa
| | - Shune V. Oliver
- Malaria Entomology Research Unit, Faculty of Health Sciences, School of Pathology, University of the Witwatersrand, Johannesburg, South Africa
- Vector Control Reference Unit, National Institute for Communicable Diseases, National Health Laboratory Service (NHLS), Johannesburg, South Africa
| | - Kwang S. Choi
- Malaria Entomology Research Unit, Faculty of Health Sciences, School of Pathology, University of the Witwatersrand, Johannesburg, South Africa
- Vector Control Reference Unit, National Institute for Communicable Diseases, National Health Laboratory Service (NHLS), Johannesburg, South Africa
| | - Basil D. Brooke
- Malaria Entomology Research Unit, Faculty of Health Sciences, School of Pathology, University of the Witwatersrand, Johannesburg, South Africa
- Vector Control Reference Unit, National Institute for Communicable Diseases, National Health Laboratory Service (NHLS), Johannesburg, South Africa
| | - Richard H. Hunt
- Malaria Entomology Research Unit, Faculty of Health Sciences, School of Pathology, University of the Witwatersrand, Johannesburg, South Africa
- School of Animal, Plant, and Environmental Sciences, University of Witwatersrand, Johannesburg, South Africa
| | - Maureen Coetzee
- Malaria Entomology Research Unit, Faculty of Health Sciences, School of Pathology, University of the Witwatersrand, Johannesburg, South Africa
- Vector Control Reference Unit, National Institute for Communicable Diseases, National Health Laboratory Service (NHLS), Johannesburg, South Africa
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Kaiser ML, Koekemoer LL, Coetzee M, Hunt RH, Brooke BD. Staggered larval time-to-hatch and insecticide resistance in the major malaria vector Anopheles gambiae S form. Malar J 2010; 9:360. [PMID: 21156042 PMCID: PMC3020156 DOI: 10.1186/1475-2875-9-360] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2010] [Accepted: 12/14/2010] [Indexed: 11/10/2022] Open
Abstract
Background Anopheles gambiae is a major vector of malaria in the West African region. Resistance to multiple insecticides has been recorded in An. gambiae S form in the Ahafo region of Ghana. A laboratory population (GAH) established using wild material from this locality has enabled a mechanistic characterization of each resistance phenotype as well as an analysis of another adaptive characteristic - staggered larval time-to-hatch. Methods Individual egg batches obtained from wild caught females collected from Ghana and the Republic of the Congo were monitored for staggered larval time-to-hatch. In addition, early and late larval time-to-hatch sub-colonies were selected from GAH. These selected sub-colonies were cross-mated and their hybrid progeny were subsequently intercrossed and back-crossed to the parental strains. The insecticide susceptibilities of the GAH base colony and the time-to-hatch selected sub-colonies were quantified for four insecticide classes using insecticide bioassays. Resistance phenotypes were mechanistically characterized using insecticide-synergist bioassays and diagnostic molecular assays for known reduced target-site sensitivity mutations. Results Anopheles gambiae GAH showed varying levels of resistance to all insecticide classes. Metabolic detoxification and reduced target-site sensitivity mechanisms were implicated. Most wild-caught families showed staggered larval time-to-hatch. However, some families were either exclusively early hatching or late hatching. Most GAH larvae hatched early but many egg batches contained a proportion of late hatching larvae. Crosses between the time-to-hatch selected sub-colonies yielded ambiguous results that did not fit any hypothetical models based on single-locus Mendelian inheritance. There was significant variation in the expression of insecticide resistance between the time-to-hatch phenotypes. Conclusions An adaptive response to the presence of multiple insecticide classes necessarily involves the development of multiple resistance mechanisms whose effectiveness may be enhanced by intra-population variation in the expression of resistance phenotypes. The variation in the expression of insecticide resistance in association with selection for larval time-to-hatch may induce this kind of enhanced adaptive plasticity as a consequence of pleiotropy, whereby mosquitoes are able to complete their aquatic life stages in a variable breeding environment using staggered larval time-to-hatch, giving rise to an adult population with enhanced variation in the expression of insecticide resistance.
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Affiliation(s)
- Maria L Kaiser
- Malaria Entomology Research Unit, School of Pathology, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa
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Brooke BD, Koekemoer LL. Major effect genes or loose confederations? The development of insecticide resistance in the malaria vector Anopheles gambiae. Parasit Vectors 2010; 3:74. [PMID: 20716346 PMCID: PMC2930636 DOI: 10.1186/1756-3305-3-74] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2010] [Accepted: 08/17/2010] [Indexed: 11/10/2022] Open
Abstract
Insecticide use in public health and agriculture presents a dramatic adaptive challenge to target and non-target insect populations. The rapid development of genetically modulated resistance to insecticides is postulated to develop in two distinct ways: By selection for single major effect genes or by selection for loose confederations in which several factors, not normally associated with each other, inadvertently combine their effects to produce resistance phenotypes. Insecticide resistance is a common occurrence and has been intensively studied in the major malaria vector Anopheles gambiae, providing a useful model for examining how insecticide resistance develops and what pleiotropic effects are likely to emerge as a consequence of resistance. As malaria vector control becomes increasingly reliant on successfully managing insecticide resistance, the characterisation of resistance mechanisms and their pleiotropic effects becomes increasingly important.
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Affiliation(s)
- Basil D Brooke
- Malaria Entomology Research Unit, School of Pathology of the University of the Witwatersrand and the National Health Laboratory Service, Johannesburg, South Africa.
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Hoffmann AA, Rieseberg LH. Revisiting the Impact of Inversions in Evolution: From Population Genetic Markers to Drivers of Adaptive Shifts and Speciation? Annu Rev Ecol Evol Syst 2008; 39:21-42. [PMID: 20419035 DOI: 10.1146/annurev.ecolsys.39.110707.173532] [Citation(s) in RCA: 409] [Impact Index Per Article: 25.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
There is a growing appreciation that chromosome inversions affect rates of adaptation, speciation, and the evolution of sex chromosomes. Comparative genomic studies have identified many new paracentric inversion polymorphisms. Population models suggest that inversions can spread by reducing recombination between alleles that independently increase fitness, without epistasis or coadaptation. Areas of linkage disequilibrium extend across large inversions but may be interspersed by areas with little disequilibrium. Genes located within inversions are associated with a variety of traits including those involved in climatic adaptation. Inversion polymorphisms may contribute to speciation by generating underdominance owing to inviable gametes, but an alternative view gaining support is that inversions facilitate speciation by reducing recombination, protecting genomic regions from introgression. Likewise, inversions may facilitate the evolution of sex chromosomes by reducing recombination between sex determining alleles and alleles with sex-specific effects. However, few genes within inversions responsible for fitness effects or speciation have been identified.
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Affiliation(s)
- Ary A Hoffmann
- Centre for Environmental Stress and Adaptation Research, Department of Genetics, University of Melbourne, Parkville, Victoria 3010 Australia;
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Abstract
Anopheles mosquitoes are the primary vectors for malaria in Africa, transmitting the disease to more than 100 million people annually. Recent functional studies have revealed mosquito genes that are crucial for Plasmodium development, but there is presently little understanding of which genes mediate vector competence in the wild, or evolve in response to parasite-mediated selection. Here, we use population genetic approaches to study the strength and mode of natural selection on a suite of mosquito immune system genes, CTL4, CTLMA2, LRIM1, and APL2 (LRRD7), which have been shown to affect Plasmodium development in functional studies. We sampled these genes from two African populations of An. gambiae s.s., along with several closely related species, and conclude that there is no evidence for either strong directional or balancing selection on these genes. We highlight a number of challenges that need to be met in order to apply population genetic tests for selection in Anopheles mosquitoes; in particular the dearth of suitable outgroup species and the potential difficulties that arise when working within a closely-related species complex.
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Affiliation(s)
- D J Obbard
- Institute of Evolutionary Biology, University of Edinburgh, Kings Buildings, West Mains Road, Edinburgh, UK.
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