title: Co-occurrence of East and West African kdr mutations suggests high levels of resistance to pyrethroid insecticides in Anopheles gambiae from Libreville, Gabon.
abstract: Point mutations in the voltage-gated sodium channel gene involved in knockdown resistance to DDT and pyrethroid insecticides have been described in several insect species. In the malaria vector Anopheles gambiae Giles sensu stricto (Diptera: Culicidae) two mutations have been identified. The first, consisting of a leucine-phenylalanine substitution at amino acid position 1014, is widespread in West Africa. The second, a leucine-serine substitution at the same position, has to date only been detected in western Kenya. Analysis of the kdr polymorphism in a sample of 106 An. gambiae s.s. of the rDNA S-form/Type I collected in Libreville (Gabon) surprisingly revealed the presence of both East and West African kdr mutations with frequencies of 63% and 37%, respectively. No wild-type alleles were detected and there was an excess of heterozygous genotypes (P = 0.04). In addition, an inconsistency was found during the kdr genotyping procedures by polymerase chain reaction, which could have lead to an underestimation of resistance alleles. The implications of these findings are discussed.
authors.affiliation: Centro de Malária e outras Doenças Tropicais, Instituto de Higiene e Medicina Tropical, Universidade Nova de Lisboa, Lisboa, Portugal. jpinto@ihmt.unl.pt
authors.forename: J
authors.initials: J
authors.lastname: Pinto
authors.forename: A
authors.initials: A
authors.lastname: Lynd
authors.forename: N
authors.initials: N
authors.lastname: Elissa
authors.forename: M J
authors.initials: MJ
authors.lastname: Donnelly
authors.forename: C
authors.initials: C
authors.lastname: Costa
authors.forename: G
authors.initials: G
authors.lastname: Gentile
authors.forename: A
authors.initials: A
authors.lastname: Caccone
authors.forename: V E
authors.initials: VE
authors.lastname: do Rosário
mesh_terms: D000818:Animals; D000852:Anopheles / Q000235:genetics* / Q000502:physiology; D016010:Binomial Distribution; D004275:DNA, Ribosomal / Q000737:chemistry; D005681:Gabon; D005787:Gene Frequency / Q000235:genetics; D017344:Genes, Insect / Q000235:genetics; D014644:Genetic Variation; D005838:Genotype; D007303:Insect Vectors / Q000235:genetics* / Q000502:physiology; D007305:Insecticide Resistance / Q000235:genetics*; D015640:Ion Channel Gating / Q000235:genetics*; D009032:Mosquito Control; D020125:Mutation, Missense / Q000235:genetics / Q000502:physiology*; D017354:Point Mutation; D016133:Polymerase Chain Reaction / Q000592:standards / Q000662:veterinary; D011722:Pyrethrins; D015222:Sodium Channels / Q000235:genetics*
chemical_list: D004275:DNA, Ribosomal; D011722:Pyrethrins; D015222:Sodium Channels