Evolutionary trade-offs associated with copy number variations in resistance alleles in Culex pipiens mosquitoes

Abstract

AbstractOrganophosphate and carbamate insecticides have largely been used worldwide to control mosquito populations. As a response, the same amino acid substitution in theace-1gene (G119S), conferring resistance to both insecticides, has been selected independently in many mosquito species. InAnopheles gambiae, it has recently been shown that the G119S mutation is actually part of homogeneous duplications that associate multiple resistance copies of theace-1gene. In this study, we showed that duplications of resistance copies of theace-1gene also exist in theCulex pipiensspecies complex. The number of copies is variable, and different numbers of copies are associated with different phenotypic trade-offs: we used a combination of bioassays and competition in population cages to show that having more resistance copies conferred higher resistance levels, but was also associated with higher selective disadvantage (or cost) in the absence of insecticide. These results further show the versatility of the genetic architecture of resistance to organophosphate and carbamate insecticides around theace-1locus and its role in fine-tuned adaptation to insecticide treatment variations.Graphical Abstract