Genetic structure of Anopheles gambiae s.s populations following the use of insecticides on several consecutive years in southern Benin

• Published in: Tropical medicine and health 2019-04, Vol.47 (1), p.23-23, Article 23
• Main Authors: Fassinou, Arsène Jacques Y H, Koukpo, Come Z, Ossè, Razaki A, Agossa, Fiacre R, Assogba, Benoit S, Sidick, Aboubakar, Sèwadé, Wilfrid T, Akogbéto, Martin C, Sèzonlin, Michel
• Format: Article
• Language: English
• Subjects: Anopheles gambiae s.l; Benin; Cotton; Fisheries; Genes; Genetic structure; Insecticides; Malaria; Mosquitoes; Mutation; Public health; Resistance
• ISSN: 1348-8945; 1349-4147; 1349-4147
• DOI: 10.1186/s41182-019-0151-z

Several studies have reported the strong resistance of complex species to pyrethroids. The voltage-dependent sodium channel ( ) gene is the main target of pyrethroids and DDT. In Benin, the frequency of the resistant allele ( ) of this gene varies along the north-south transect. Monitoring the evolution of resistance is necessary to better appreciate the genetic structure of vector populations in localities subject to the intensive use of chemicals associated with other control initiatives. The purpose of this study was to map the distribution of pyrethroid insecticide resistance alleles of the gene in malaria vectors in different regions and ecological facies in order to identify the evolutionary forces that might be the basis of anopheline population dynamics. The characterization of populations and resistance mechanisms were performed using adult mosquitoes obtained from larvae collected in the four agroecological zones in southern Benin. Genomic DNA extraction was performed on whole mosquitoes.The extracted genomic DNA from them were used for the molecular identification of species in complex and the identification of genotypes related to pyrethroid resistance as the gene amino acid position 1014 in sodium channel. Molecular speciation and genotyping of resistant alleles (1014) were done using PCR.Genepop software version 4.2 was used to calculate allelic and genotypic frequencies in each agroecological zone. The value of the allelic frequency was determined using the binomial test function in R version 3.3.3. The Hardy-Weinberg equilibrium was checked for each population with Genetics software version 1.3.8.1. The observed heterozygosity and the expected heterozygosity as well as the fixation index and genetic differentiation index within and between populations were calculated using Genepop software version 4.2. During the study period, was the major species in all agroecological zones while was scarcely represented. Regardless of the species, resistant homozygote individuals ( ) were dominant in all agroecological zones, showing a strong selection of the resistant allele ( ). All populations showed a deficit of heterozygosity. No genetic differentiation was observed between the different populations of the two species. For , there was a small differentiation among the populations of the central cotton and bar-lands zones. The genetic differentiation was modest among the population of the fisheries zone (  = 0.1295). The genetic differentiation was v