Molecular analysis of population genetic variability and insecticide resistance of the yellow fever mosquito in Trinidad and Tobago - abstract

ABSTRACT

Spatial patterns of genetic variants in natural populations are the combined effects of various evolutionary forces and demographic structure. Population life history and mating structure have genome-wide effect, but selection, affects only the target loci or closely-linked loci. This study examines the spatial patterns of 4 natural Aedes aegypti populations of Trinidad and Tobago, through registration fragment length polymorphism (RFLP) analysis of 16 genetic loci representative of mosquito genome on 870 individuals. These populations have been subjected to numerous organophosphate (OP) insecticides for more than 2 decades, but have not been subjected to DDT over this period. We predicted that genes closely-linked to the OP target loci would be strongly affected in gene polymorphism, and probably be the most differentiated loci in the genome, but gene flow has homogenized frequencies for the gene conferring resistance to DDT. As predicted, low DNA polymorphisms and gene deletions were found for loci in the general chromosomal region of the OP target site, and these exhibited large scale FST value. The gene conferring resistance to DDT shows similar polymorphisms and genetic differentiation to other loci in the genome. We concluded that gene flow was not sufficiently frequent to prevent genetic differentiation due to genetic drift or selection, but could be a powerful force for the spread of insectide resistance genes. (AU)