Evidence of increasing L1014F kdr mutation frequency in Anopheles gambiae s.l.pyrethroid resistant following a nationwide distribution of LLINs by the Beninese National Malaria Control Programme

Objective:To determine the susceptibility status to pyrethroid in Anopheles gambiae s.l.(An.gambiae),the distribution of kdr"Leu-Phe"mutation in malaria vectors in Benin and to compare the current frequency of kdr"Leu-Phe"mutation to the previous frequency after long-lasting insecticide treated nets implementation.Methods:Larvae and pupae of An.gambiae s.l.mosquitoes were collected from the breeding sites in Littoral,Zou.Borgou and Alibori provinces.CDC susceptibility tests were conducted on unfed females mosquitoes aged 2-5 d old.An.gambiae mosquitoes were identified to species using PCR techniques.Molecular assays were also carried out to identify kdr mutations in individual mosquitoes.Results:The results showed that An.gambiae Malanville and Suru-lere populations were resistant to deltamethrin.Regarding An.gambiae Parakou and Bohicon populations,they were resistant to permethrin.PCR revealed 100%of mosquitoes tested were An.gambiae s.s.The L1014F kdr mutation was found in An.gambiae s.s.Malanville and Parakou at various allelic frequencies.The increase of kdr allelic frequency was positively correlated with CDC bioassays data.Conclusions:Pyrethroid resistance is widespread in malaria vector in Benin and kdr mutation is the main resistance mechanism involved.More attention may be paid for the future success of malaria control programmes based on LLINs with pyrethroids in the country.