title: Relationship between kdr mutation and resistance to pyrethroid and DDT insecticides in natural populations of Anopheles gambiae.
abstract: 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.
authors.affiliation: Department of Entomology and Center for Vectorborne Diseases, University of California Davis, Davis, CA 95616, USA. ljreimer@ucdavis.edu
authors.forename: Lisa
authors.initials: L
authors.lastname: Reimer
authors.forename: Etienne
authors.initials: E
authors.lastname: Fondjo
authors.forename: Salomon
authors.initials: S
authors.lastname: Patchoké
authors.forename: Brehima
authors.initials: B
authors.lastname: Diallo
authors.forename: Yoosook
authors.initials: Y
authors.lastname: Lee
authors.forename: Arash
authors.initials: A
authors.lastname: Ng
authors.forename: Hamadou M
authors.initials: HM
authors.lastname: Ndjemai
authors.forename: Jean
authors.initials: J
authors.lastname: Atangana
authors.forename: Sekou F
authors.initials: SF
authors.lastname: Traore
authors.forename: Gregory
authors.initials: G
authors.lastname: Lanzaro
authors.forename: Anthony J
authors.initials: AJ
authors.lastname: Cornel
mesh_terms: D000483:Alleles; D000818:Animals; D000852:Anopheles / Q000235:genetics*; D002163:Cameroon; D003634:DDT; D005787:Gene Frequency; D007305:Insecticide Resistance / Q000235:genetics; D007306:Insecticides; D011722:Pyrethrins; D015222:Sodium Channels / Q000235:genetics*
chemical_list: D007306:Insecticides; D011722:Pyrethrins; D015222:Sodium Channels; D003634:DDT