Pyrethroid resistance in Aedes aegypti populations in southern Benin, West Africa

Aedes aegypti the main vector of dengue fever is present year round in several cities of the Republic of Benin. It is therefore unfortunate that the international focus is on Anopheles control and not so much on Ae. Aegypti, a rather more resilient mosquito to many insecticides that deserves attention. In this study, we assessed the resistance status of Ae. Aegypti to organochlorine, pyrethroids and carbamates. We collected Ae. Aegypti mosquitoes in Dandji from June to August 2017. Bioassay tests were performed to assess the susceptibility of dengue vectors to various agricultural insecticides where females mosquitoes aged 2-5 days old were exposed to five insecticide impregnated papers (permethrin at 0.75%; deltamethrin at 0.05%; DDT at 4%, lambdacyhalothrin (0.05%) and bendiocarb at 0.1%) following WHOPES guidelines. Results from this study showed that Ae. Aegypti developed a strong resistance to DDT (10% of mortality), and moderate resistance to pyrethroids (35% with permethrin, 60% with deltamethrin and 72% with lambdacyhalothrin). However, the same populations were fully susceptible to bendiocarb These findings show for the first time in Benin the resistance of Ae. Aegypti populations to organochlorines and pyrethroids. Measures must be taken by Benin Health authorities for a continuous monitoring of the susceptibility of Ae. Aegypti across the country. These measures will enable the selection of effective insecticides for arbovirus control in Benin in case of a dengue fever outbreak.