The kdr mutation occurs in the Mopti form of Anopheles gambiae s.s. through introgression

Anopheles gambiae s.s. is a complex of sibling taxa characterized by variou s paracentric inversions. In west and central Africa, where several taxa ar e sympatric, a kdr mutation responsible for pyrethroid resistance has been described in only one (the S taxon), suggesting an absence of gene flow bet ween them. Following a thorough sampling, we have found a kdr mutation in a nother taxon (M). To establish whether this mutation is the same event or n ot, the large intron upstream of the kdr mutation was sequenced to find pol ymorphic sites in susceptible/resistant and M/S mosquitoes. The low genetic diversity found in this DNA region indicates that a local genetic sweep ha s recently occurred. However, some polymorphic sites were found, and it is therefore concluded that the kdr mutation in the M taxon is not an independ ent mutation event, and is best explained by an introgression from the S ta xon. These results are discussed within the context of possible gene flow b etween members of An. gambiae s.s. taxa, and with the possible spread of th e kdr mutation in other closely related malaria vectors of the An. gambiae complex.