Synergist bioassay in permethrin and DDT cross-resistance in the population of <i>Anopheles funestus</i> S.L complex from Sahel region of Katsina State Nigeria

Insecticide resistance, a phenomenon where most insect become less susceptible to the effects of insecticides, poses a significant challenge to mosquito-borne diseases control efforts worldwide. The aim of this study is to identify the Anopheles funestus s.l complex and it’s insecticide profile resistance. The study was carried out in Gajerar Giwa and Kadaji villages in the Sahel region of Katsina state. Using a mechanical aspirator, blood-feeding mosquitoes were captured indoors and identified morphologically and molecularly. Insecticide susceptibility test using F1 mosquitoes was carried out according to WHO procedure. Mosquitoes were identified as Anopheles funestus s.s and insecticide susceptibility test revealed that Anopheles funestus s.s from Gajerar Giwa and Kadaji hamlets were susceptible to deltamethrin recorded 98.5% and 65.23% respectively after 24 hours post exposure, but resistant to permethrin and dichloro-diphenyl-trichloroethane (DDT) recorded 44.2%, 31.4% from Gajerar Giwa and 32.7%, 28.1% from Kadaji after 24 hours post exposure. Synergist bioassay result of F1 Anopheles funestus s.s recorded increased in mortality rate from 44.2 to 62.4% after being exposed to 4% piperonyl butoxide (PBO) and permethrin, indicating P450 monooxygenase played a major role in pyrethroid resistance. The execution of an effective vector control strategy can be guided by the presence of permethrin and DDT cross resistance in the population of Anopheles funestus s.s.