Insecticide Resistance in Mosquitoes: Possible Detection of F1534C, S989P, and V1016G Triple Mutation in Benin, West Africa.

Epidemics of arboviruses in general, and dengue fever in particular, are an increasing threat in areas where is present. The effectiveness of chemical control of is jeopardized by the increasing frequency of insecticide resistance. The aim of this study was to determine the susceptibility status of to public health insecticides and assess the underlying mechanisms driving insecticide resistance. eggs were collected in two study sites in the vicinity of houses for two weeks using gravid traps (GATs). After rearing the mosquitoes to adulthood, female were exposed to diagnostic doses of permethrin, deltamethrin and bendiocarb, using Centers for Disease Control and Prevention (CDC) bottle bioassays. Unexposed, un-engorged female were tested individually for mixed-function oxidase (MFO), glutathione--transferase (GST) and α and β esterase activities. Finally, allele-specific PCR (AS-PCR) was used to detect possible mutations (F1534C, S989P, and V1016G) in the voltage-gated sodium channel gene in insecticide-exposed Most traps were oviposition positive; 93.2% and 97% of traps contained eggs in the 10 arrondissement of Cotonou and in Godomey-Togoudo, respectively. Insecticide bioassays detected resistance to permethrin and deltamethrin in both study sites and complete susceptibility to bendiocarb. By comparison to the insecticide-susceptible Rockefeller strain, field populations had significantly higher levels of GSTs and significantly lower levels of α and β esterases; there was no significant difference between levels of MFOs. AS-PCR genotyping revealed the possible presence of 3 mutations (F1534C, S989P, and V1016G) at high frequencies; 80.9% (228/282) of the tested had at least 1 mutation, while the simultaneous presence of all 3 mutations was identified in 13 resistant individuals. Study findings demonstrated phenotypic pyrethroid resistance, the over-expression of key detoxification enzymes, and the possible presence of several mutations in populations, emphasizing the urgent need to implement vector control strategies targeting arbovirus vector species in Benin.