Identification of new candidates for metabolic insecticide detoxification through RNA sequencing of negative-cross resistant mosquito field populations.

We hypothesise that up-regulation of detoxifying enzymes that degrade pyrethroids might confer negative-cross resistance, making malathion more toxic to pyrethroid-resistant mosquitoes. By means of RNA sequencing (RNA-Seq) we aim to investigate differential gene expression between resistant and susceptible mosquito populations. To test our hypothesis we are addressing the following two specific research aims: 1) To characterise the gene expression profiles of phenotyped An. coluzzii field populations with focus on cytochrome P450s and 2) to test if genes differentially expressed between insecticide resistance phenotypes are induced upon insecticide exposure or if they are constitutively over-expressed. In addition to the survivors of the 10x diagnostic pyrethroid concentration and the 0.5x diagnostic concentration of malathion we will also sequence the RNA of field samples that were unexposed to insecticide. The An. coluzzii laboratory strain N’Gousso will serve as the insecticide-susceptible control. We will subject control samples with the same experimental conditions as for the pyrethroid-resistant field population to RNA-Seq, meaning exposed to both insecticides at sublethal concentrations and unexposed specimens.