Characterization of Anopheles gambiae breeding sites and insecticide resistance mechanisms in urban areas of Cotonou and Natitingou, Benin

Background: This study aimed to investigate the relationship between the physicochemical characteristics of An. gambiae and An. Coluzzii breeding sites, the susceptibility to common insecticides used in public health, and the underlying insecticide resistance mechanisms. Methods Anopheles breeding sites surveys were conducted in Cotonou and Natitingou. Physicochemical parameters and bacterial loads were determined in individual breeding sites. The WHO susceptibility assays were carried out using the female of the emerging adult mosquitoes. Anopheles species were identified through PCR techniques. Kdr L1014F/S, N1575Y and G119S mutations were investigated using TaqMan genotyping assays. Results Molecular analysis showed that all mosquitoes analyzed in Cotonou were Anopheles coluzzii , while those of Natitingou were Anopheles gambiae s.s. WHO susceptibility assay indicated a high level of resistance to deltamethrin in the two cities. The resistance levels to deltamethrin were higher in Cotonou (X 2  = 31.689; DF = 1; P < 0.0001). There was a suspicion of resistance to bendiocarb in Cotonou, whereas the mosquito population in Natitingou was resistant. The kdr L1014F mutation was highly observed in both mosquito populations, while the Ace-1 mutation was found in a small proportion of mosquitoes. In Cotonou, salinity was the only recorded physicochemical parameter significantly correlated with the resistance of Anopheles mosquitoes to deltamethrin. In Natitingou, significant correlations were observed between the allelic frequencies of the kdr L1014F mutation and pH, conductivity, and TDS. Conclusion These results indicate a high level of pyrethroid resistance in the An. gambiae population of both Cotonou and Natitingou. Moreover, the data suggest the involvement of the kdr mutation and possibly the breeding sites abiotic factors.