Relationship Between kdr Mutation and Resistance to Pyrethroid and DDT Insecticides in Natural Populations of Anopheles gambiae

• Published in: Journal of medical entomology Vol. 45; no. 2; pp. 260 - 266
• Main Authors: Reimer, L, Fondjo, E, Patchoke, S, Diallo, B, Lee, Y, Ng, A, Ndjemai, H.M, Atangana, J, Traore, S.F, Lanzaro, G
• Format: Journal Article
• Language: English
• Published: England 01.03.2008
• Subjects: Alleles; amino acid substitution; Animals; Anopheles - genetics; Anopheles gambiae; Cameroon; DDT; DDT (pesticide); Gene Frequency; genetic polymorphism; genetic resistance; genotype; insecticide resistance; Insecticide Resistance - genetics; Insecticides; knockdown resistance; M molecular form; mutation; population genetics; Pyrethrins; pyrethroid insecticides; resistance alleles; S molecular forms; sodium channels; Sodium Channels - genetics; Cameroon
• DOI: 10.1603/0022-2585%282008%2945%5B260%3ARBKMAR%5D2.0.CO%3B2
• ISSN: 0022-2585

The spread of insecticide resistance genes in Anopheles gambiae Giles sensu stricto threatens to compromise vector-based malaria control programs. Two mutations at the same locus in the voltage-gated sodium channel gene are known to confer knockdown resistance (kdr) to pyrethroids and DDT. Kdr-e involves a leucine-serine substitution, and it was until recently thought to be restricted to East Africa, whereas kdr-w, which involves a leucine-phenylalanine substitution, is associated with resistance in West Africa. In this study, we analyze the frequency and relationship between the kdr genotypes and resistance to type I and type II pyrethroids and DDT by using WHO test kits in both the Forest-M and S molecular forms of An. gambiae in Cameroon. Both kdr-w and kdr-e polymorphisms were found in sympatric An. gambiae, and in many cases in the same mosquito. Kdr-e and kdr-w were detected in both forms, but they were predominant in the S form. Both kdr-e and kdr-w were closely associated with resistance to DDT and weakly associated with resistance to type II pyrethroids. Kdr-w conferred greater resistance to permethrin than kdr-e. We also describe a modified diagnostic designed to detect both resistant alleles simultaneously.