Co-occurrence of East and West African kdr mutations suggests high levels of resistance to pyrethroid insecticides in Anopheles gambiae from Libreville, Gabon.
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.
Pinto
J
J
Centro de Malária e outras Doenças Tropicais, Instituto de Higiene e Medicina Tropical, Universidade Nova de Lisboa, Lisboa, Portugal. jpinto@ihmt.unl.pt
Lynd
A
A
Elissa
N
N
Donnelly
M J
MJ
Costa
C
C
Gentile
G
G
Caccone
A
A
do Rosário
V E
VE
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*
D004275:DNA, Ribosomal; D011722:Pyrethrins; D015222:Sodium Channels