Dynamics of organophosphate and carbamate resistance in Anopheles gambiae s. l. populations from south and north Benin, West Africa

The current study was aimed to investigate on dynamics of propoxur resistance in Anopheles gambiae s.l. populations from N’ dali district in northern Benin (West Africa) and also to investigate on dynamics of malathion resistance in Anopheles gambiae s. l. populations from Toffo district in southern Benin. Larvae and pupae of Anopheles gambiae s. l . mosquitoes were collected from the breeding sites in Borgou and Atlantic departments in 2015 and 2019. WHO susceptibility tests were conducted on unfed female mosquitoes aged 2-5 days old. WHO bioassays were performed with impregnated papers with propoxur 0.1% and with malathion 5%. PCR techniques were used to detect species and Ace-1 mutations in 2015. Anopheles gambiae s. l. populations from N’dali were resistant to propoxur in 2015 and were still remained resistant to this product in 2019. Regarding Anopheles gambiae s. l. populations from Toffo, they were susceptible to malathion in 2015 whereas the malathion resistance status of these mosquitoes requires further investigation in 2019. PCR revealed that all specimens tested were Anopheles gambiae s. s. The presence of Ace-1R at very low frequency (0.01) was observed in Anopheles gambiae s. l. populations from both districts. This study shows that propoxur resistance detected in An. gambiae s. l. populations from N’ dali needs to be monitored for insecticide resistance in this area.