Here, we investigated the molecular mechanisms of insecticide resistance in three Anopheles coluzzii field populations from southern Cote d Ivoire, including Agboville, Dabou and Tiassale.
More...Here, we investigated the molecular mechanisms of insecticide resistance in three Anopheles coluzzii field populations from southern Cote d Ivoire, including Agboville, Dabou and Tiassale. All three populations were resistant to bendiocarb, deltamethrin and DDT, but not or only very weakly resistant to malathion. The absence of malathion resistance is an unexpected result because we found the acetylcholinesterase mutation Ace1 G280S at high frequencies, which would typically confer cross-resistance to carbamates and organophosphates, including malathion. Prior to RNA extraction using TRI Reagent, we exposed all mosquitoes using WHO tube bioassays for 1 h to either 6.4% deltamethrin, 2.5% malathion or non-insecticide control papers and preserved them in RNAlater (three experimental conditions). Only individuals that were alive 24 h post-exposure were sequenced. All specimens were laboratory-reared, 3 to 6 day old adult females that were non blood-fed and presumably mated. We identified all specimens as An. coluzzii using a species-specific qPCR assay. We subjected RNA of five individuals i.e. five biological replicates per mosquito population and experimental condition to RNA sequencing. We included insecticide unexposed control specimens from the three multiresistant populations collected at larval stage in Cote d Ivoire (Agboville, Dabou and Tiassale) and two insecticide susceptible laboratory strains (Mali NIH and Ngousso). Additionally, we included specimens that survived insecticide exposure only from the three Ivorian populations.
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