title: How the malaria vector Anopheles gambiae adapts to the use of insecticide-treated nets by African populations.
abstract: BACKGROUND
  Insecticide treated bed nets have been recommended and proven efficient as a measure to protect African populations from malaria mosquito vector Anopheles spp. This study evaluates the consequences of bed nets use on vectors resistance to insecticides, their feeding behavior and malaria transmission in Dielmo village, Senegal, were LLINs were offered to all villagers in July 2008.
  
  
  METHODS
  Adult mosquitoes were collected monthly from January 2006 to December 2011 by human landing catches (HLC) and by pyrethroid spray catches (PCS). A randomly selected sub-sample of 15-20% of An. gambiae s.l. collected each month was used to investigate the molecular forms of the An. gambiae complex, kdr mutations, and Plasmodium falciparum circumsporozoite (CSP) rate. Malaria prevalence and gametocytaemia in Dielmo villagers were measured quarterly.
  
  
  RESULTS
  Insecticide susceptible mosquitoes (wild kdr genotype) presented a reduced lifespan after LLINs implementation but they rapidly adapted their feeding behavior, becoming more exophageous and zoophilic, and biting earlier during the night. In the meantime, insecticide-resistant specimens (kdr L1014F genotype) increased in frequency in the population, with an unchanged lifespan and feeding behaviour. P. falciparum prevalence and gametocyte rate in villagers decreased dramatically after LLINs deployment. Malaria infection rate tended to zero in susceptible mosquitoes whereas the infection rate increased markedly in the kdr homozygote mosquitoes.
  
  
  CONCLUSIONS
  Dramatic changes in vector populations and their behavior occurred after the deployment of LLINs due to the extraordinary adaptative skills of An. gambiae s. l. mosquitoes. However, despite the increasing proportion of insecticide resistant mosquitoes and their almost exclusive responsibility in malaria transmission, the P. falciparum gametocyte reservoir continued to decrease three years after the deployment of LLINs.
authors.affiliation: G4-Group, Institut Pasteur International Network, Entomology Unit, Institut Pasteur of Bangui, Bangui, Central African Republic.
authors.forename: Mamadou Ousmane
authors.initials: MO
authors.lastname: Ndiath
authors.affiliation: Laboratoire de Paludologie et de Zoologie Médicale, Institut de Recherche pour le Développement, Campus International UCAD- IRD, Hann, Dakar, Sénégal.
authors.forename: Catherine
authors.initials: C
authors.lastname: Mazenot
authors.affiliation: Unité de Recherche sur les Maladies Infectieuses et Tropicales Emergentes, IRD198, UM63, CNRS7278, INSERMU1095, Aix-Marseille Université, Campus UCAD-IRD, BP 1386, Dakar, Sénégal.
authors.forename: Cheikh
authors.initials: C
authors.lastname: Sokhna
authors.affiliation: Laboratoire de Paludologie et de Zoologie Médicale, Institut de Recherche pour le Développement, Campus International UCAD- IRD, Hann, Dakar, Sénégal.
authors.forename: Jean-François
authors.initials: JF
authors.lastname: Trape
mesh_terms: D000222:Adaptation, Physiological; D000349:Africa; D000818:Animals; D000852:Anopheles / Q000235:genetics / Q000502:physiology*; D005247:Feeding Behavior; D005838:Genotype; D005854:Germ Cells / Q000378:metabolism; D006801:Humans; D007303:Insect Vectors / Q000235:genetics / Q000502:physiology*; D057148:Insecticide-Treated Bednets; D008288:Malaria / Q000469:parasitology*; D015800:Protozoan Proteins / Q000378:metabolism; D013045:Species Specificity; D013997:Time Factors
chemical_list: D015800:Protozoan Proteins; C041595:circumsporozoite protein, Protozoan