title: Insecticide susceptibility of natural populations of Anopheles coluzzii and Anopheles gambiae (sensu stricto) from Okyereko irrigation site, Ghana, West Africa.
abstract: BACKGROUND
  The increasing spread of insecticide resistance in malaria vectors has been well documented across sub-Saharan Africa countries. The influence of irrigation on increasing vector resistance is poorly understood, and is critical to successful and ethical implementation of food security policies. This study investigated the insecticide resistance status of An. gambiae (s.l.) mosquitoes collected from the irrigated rice area of Okyereko, a village containing about 42 hectares of irrigated field within an irrigation project plan in the Central Region of Ghana. Large amounts of insecticides, herbicides and fertilizers are commonly used in the area to boost the annual production of the rice.
  
  
  METHODS
  Mosquito larvae were collected and adults were assayed from the F1 progeny. The resistance status, allele and genotype were characterized using WHO susceptibility testing and PCR methods respectively.
  
  
  RESULTS
  The An. gambiae (s.l.) populations from Okyereko are highly resistant to DDT and pyrethroid insecticides, with possible involvement of metabolic mechanisms including the elevation of P450 and GST enzyme as well as P-gp activity. The population was mostly composed of An. coluzzii specimens (more than 96 %) with kdr and ace-1 frequencies of 0.9 and 0.2 %, respectively.
  
  
  CONCLUSIONS
  This study brings additional information on insecticide resistance and the characterization of An. gambiae (s.l.) mosquitoes from Okyereko, which can be helpful in decision making for vector control programmes in the region.
authors.affiliation: Vestergaard-NMIMR Vector Labs (VNVL), Noguchi Memorial Institute for Medical Research, University of Ghana, Legon, Accra, Ghana. chabijoseph@yahoo.fr.|Parasitology Department, Noguchi Memorial Institute for Medical Research, University of Ghana, Legon, Accra, Ghana. chabijoseph@yahoo.fr.
authors.forename: Joseph
authors.initials: J
authors.lastname: Chabi
authors.affiliation: Department of Theoretical and Applied Biology, Kwame Nkrumah University of Science and Technology, Kumasi, Ghana.
authors.forename: Philip K
authors.initials: PK
authors.lastname: Baidoo
authors.affiliation: Vestergaard-NMIMR Vector Labs (VNVL), Noguchi Memorial Institute for Medical Research, University of Ghana, Legon, Accra, Ghana.|Parasitology Department, Noguchi Memorial Institute for Medical Research, University of Ghana, Legon, Accra, Ghana.
authors.forename: Alex K
authors.initials: AK
authors.lastname: Datsomor
authors.affiliation: Vestergaard-NMIMR Vector Labs (VNVL), Noguchi Memorial Institute for Medical Research, University of Ghana, Legon, Accra, Ghana.|Parasitology Department, Noguchi Memorial Institute for Medical Research, University of Ghana, Legon, Accra, Ghana.
authors.forename: Dora
authors.initials: D
authors.lastname: Okyere
authors.affiliation: Vestergaard-NMIMR Vector Labs (VNVL), Noguchi Memorial Institute for Medical Research, University of Ghana, Legon, Accra, Ghana.|Parasitology Department, Noguchi Memorial Institute for Medical Research, University of Ghana, Legon, Accra, Ghana.
authors.forename: Aikins
authors.initials: A
authors.lastname: Ablorde
authors.affiliation: Vestergaard-NMIMR Vector Labs (VNVL), Noguchi Memorial Institute for Medical Research, University of Ghana, Legon, Accra, Ghana.|Parasitology Department, Noguchi Memorial Institute for Medical Research, University of Ghana, Legon, Accra, Ghana.
authors.forename: Alidu
authors.initials: A
authors.lastname: Iddrisu
authors.affiliation: Parasitology Department, Noguchi Memorial Institute for Medical Research, University of Ghana, Legon, Accra, Ghana.
authors.forename: Michael D
authors.initials: MD
authors.lastname: Wilson
authors.affiliation: Parasitology Department, Noguchi Memorial Institute for Medical Research, University of Ghana, Legon, Accra, Ghana.
authors.forename: Samuel K
authors.initials: SK
authors.lastname: Dadzie
authors.affiliation: Vestergaard, Washington, DC, USA.
authors.forename: Helen P
authors.initials: HP
authors.lastname: Jamet
authors.affiliation: Vector Biology Research Program, U.S. Naval Medical Research Unit No 3, Cairo, Egypt.
authors.forename: Joseph W
authors.initials: JW
authors.lastname: Diclaro
mesh_terms: D057914:Agricultural Irrigation; D000818:Animals; D000852:Anopheles / Q000187:drug effects*; D001681:Biological Assay; D003634:DDT / Q000494:pharmacology; D005787:Gene Frequency; D017344:Genes, Insect; D005869:Ghana; D007305:Insecticide Resistance; D007306:Insecticides / Q000494:pharmacology*; D007814:Larva / Q000187:drug effects; D016133:Polymerase Chain Reaction; D011722:Pyrethrins / Q000494:pharmacology
chemical_list: D007306:Insecticides; D011722:Pyrethrins; D003634:DDT
keywords: An. coluzzii; An. gambiae s.s; Insecticide resistance; Irrigation; Malaria