title: Evidence of multiple insecticide resistance mechanisms in Anopheles gambiae populations in Bangui, Central African Republic.
abstract: Knowledge of insecticide resistance status in the main malaria vectors is an essential component of effective malaria vector control. This study presents the first evaluation of the status of insecticide resistance in Anopheles gambiae populations from Bangui, the Central African Republic.
  
  
  
  Anopheles mosquitoes were reared from larvae collected in seven districts of Bangui between September to November 2014. The World Health Organisation's bioassay susceptibility tests to lambda-cyhalothrin (0.05%), deltamethrin (0.05%), DDT (4%), malathion (5%), fenitrothion (1%) and bendiocarb (0.1%) were performed on adult females. Species and molecular forms as well as the presence of L1014F kdr and Ace-1Rmutations were assessed by PCR. Additional tests were conducted to assess metabolic resistance status.
  
  
  
  After 1 h exposure, a significant difference of knockdown effect was observed between districts in all insecticides tested except deltamethrin and malathion. The mortality rate (MR) of pyrethroids group ranging from 27% (CI: 19-37.5) in Petevo to 86% (CI: 77.6-92.1) in Gbanikola; while for DDT, MR ranged from 5% (CI: 1.6-11.3) in Centre-ville to 39% (CI: 29.4-49.3) in Ouango. For the organophosphate group a MR of 100% was observed in all districts except Gbanikola where a MR of 96% (CI: 90-98.9) was recorded. The mortality induced by bendiocarb was very heterogeneous, ranging from 75% (CI: 62.8-82.8) in Yapele to 99% (CI: 84.5-100) in Centre-ville. A high level of kdr-w (L1014F) frequency was observed in all districts ranging from 93 to 100%; however, no kdr-e (L1014S) and Ace-1Rmutation were found in all tested mosquitoes. Data of biochemical analysis showed significant overexpression activities of cytochrome P450, GST and esterases in Gbanikola and Yapele (χ2= 31.85, df = 2, P < 0.001). By contrast, esterases activities using α and β-naphthyl acetate were significantly low in mosquitoes from PK10 and Ouango in comparison to Kisumu strain (χ2= 17.34, df = 2, P < 0.005).
  
  
  
  Evidence of resistance to DDT and pyrethroids as well as precocious emergence of resistance to carbamates were detected among A. gambiae mosquitoes from Bangui, including target-site mutations and metabolic mechanisms. The co-existence of these resistance mechanisms in A. gambiae may be a serious obstacle for the future success of malaria control programmes in this region.
authors.affiliation: G4 Malaria Group, Institut Pasteur of Bangui, BP 926, Bangui, Central African Republic.|Faculté des Sciences et Techniques, Université d'Abomey Calavi, Cotonou, Benin.|Centre de Recherche Entomologique de Cotonou (CREC), Cotonou, 06 BP 2604, Benin.
authors.forename: Marina Lidwine
authors.initials: ML
authors.lastname: Olé Sangba
authors.affiliation: Centre de Recherche Entomologique de Cotonou (CREC), Cotonou, 06 BP 2604, Benin.
authors.forename: Aboubakar
authors.initials: A
authors.lastname: Sidick
authors.affiliation: Centre de Recherche Entomologique de Cotonou (CREC), Cotonou, 06 BP 2604, Benin.|Ecole Nationale des Sciences et Techniques Agricole de Djougou (ENSTA), Université des Sciences Arts et Techniques de Natitingou (USATN), Natitingou, Benin.
authors.forename: Renaud
authors.initials: R
authors.lastname: Govoetchan
authors.affiliation: University of Colorado Denver Anschutz Medical Campus, 13001 E 17th Pl, Aurora, CO, 80045, USA.
authors.forename: Christian
authors.initials: C
authors.lastname: Dide-Agossou
authors.affiliation: Centre de Recherche Entomologique de Cotonou (CREC), Cotonou, 06 BP 2604, Benin.|Ecole de Gestion et d'Exploitation des Systèmes d'Elevage (EGESE), Université d'Agriculture de Kétou (UAK), Kétou, Benin.
authors.forename: Razaki A
authors.initials: RA
authors.lastname: Ossè
authors.affiliation: Faculté des Sciences et Techniques, Université d'Abomey Calavi, Cotonou, Benin.|Centre de Recherche Entomologique de Cotonou (CREC), Cotonou, 06 BP 2604, Benin.
authors.forename: Martin
authors.initials: M
authors.lastname: Akogbeto
authors.affiliation: G4 Malaria Group, Institut Pasteur of Bangui, BP 926, Bangui, Central African Republic. ousmane.ndiath@gmail.com.|G4 Malaria Group, Institut Pasteur of Madagascar BP 1274, Ambatofotsikely Avaradoha 101, Antananarivo, Madagascar. ousmane.ndiath@gmail.com.
authors.forename: Mamadou Ousmane
authors.initials: MO
authors.lastname: Ndiath
mesh_terms: D000818:Animals; D000852:Anopheles / Q000187:drug effects* / Q000235:genetics*; D001681:Biological Assay; D002488:Central African Republic; D007305:Insecticide Resistance; D007306:Insecticides / Q000494:pharmacology; D016133:Polymerase Chain Reaction
chemical_list: D007306:Insecticides
keywords: Anopheles gambiae; Bangui; Central African Republic; Insecticide resistance; Malaria