title: Resistance to DDT and pyrethroids and increased kdr mutation frequency in An. gambiae after the implementation of permethrin-treated nets in Senegal.
abstract: BACKGROUND
  The aim of this study was to evaluate the susceptibility to insecticides of An. gambiae mosquitoes sampled in Dielmo (Senegal), in 2010, 2 years after the implementation of Long Lasting Insecticide-treated Nets (LLINs) and to report the evolution of kdr mutation frequency from 2006 to 2010.
  
  
  METHODS
  WHO bioassay susceptibility tests to 6 insecticides were performed on adults F0, issuing from immature stages of An. gambiae s.l., sampled in August 2010. Species and molecular forms as well as the presence of L1014F and L1014S kdr mutations were assessed by PCR. Longitudinal study of kdr mutations was performed on adult mosquitoes sampled monthly by night landing catches from 2006 to 2010.
  
  
  RESULTS
  No specimen studied presented the L1014S mutation. During the longitudinal study, L1014F allelic frequency rose from 2.4% in year before the implementation of LLINs to 4.6% 0-12 months after and 18.7% 13-30 months after. In 2010, An. gambiae were resistant to DDT, Lambda-cyhalothrin, Deltamethrin and Permethrin (mortality rates ranging from 46 to 63%) but highly susceptible to Fenitrothion and Bendiocarb (100% mortality). There was significantly more RR genotype among An. gambiae surviving exposure to DDT or Pyrethroids. An. arabiensis represented 3.7% of the sampled mosquitoes (11/300) with no kdr resistance allele detected. An. gambiae molecular form M represented 29.7% of the mosquitoes with, among them, kdr genotypes SR (18%) and SS (82%). An. gambiae molecular form S represented 66% of the population with, among them, kdr genotype SS (33.3%), SR (55.6%) and RR (11.1%). Only 2 MS hybrid mosquitoes were sampled and presented SS kdr genotype.
  
  
  CONCLUSIONS
  Biological evidence of resistance to DDT and pyrethroids was detected among An. gambiae mosquitoes in Dielmo (Senegal) within 24 months of community use of LLINs. Molecular identification of L1014F mutation indicated that target site resistance increased after the implementation of LLINs.
authors.affiliation: Institut de Recherche pour le Développement, Unité de Recherche sur les Maladies Infectieuses et Tropicales Emergentes UMR 198, Campus commun UCAD-IRD de Hann, BP 1386, CP 18524 Dakar, Sénégal.
authors.forename: Mamadou O
authors.initials: MO
authors.lastname: Ndiath
authors.forename: Seynabou
authors.initials: S
authors.lastname: Sougoufara
authors.forename: Abdoulaye
authors.initials: A
authors.lastname: Gaye
authors.forename: Catherine
authors.initials: C
authors.lastname: Mazenot
authors.forename: Lassana
authors.initials: L
authors.lastname: Konate
authors.forename: Ousmane
authors.initials: O
authors.lastname: Faye
authors.forename: Oumar
authors.initials: O
authors.lastname: Faye
authors.forename: Cheikh
authors.initials: C
authors.lastname: Sokhna
authors.forename: Jean-Francois
authors.initials: JF
authors.lastname: Trape
mesh_terms: D000483:Alleles; D000818:Animals; D000852:Anopheles / Q000502:physiology*; D001681:Biological Assay; D009033:Culicidae; D003634:DDT / Q000494:pharmacology*; D004252:DNA Mutational Analysis; D005838:Genotype; D007305:Insecticide Resistance; D007306:Insecticides; D009032:Mosquito Control; D057147:Mosquito Nets; D009154:Mutation; D059645:Mutation Rate; D011722:Pyrethrins / Q000494:pharmacology*; D012675:Senegal; D040301:Vascular Endothelial Growth Factor Receptor-2 / Q000235:genetics*
chemical_list: D007306:Insecticides; D011722:Pyrethrins; D003634:DDT; D040301:Vascular Endothelial Growth Factor Receptor-2