title: Evidence of a multiple insecticide resistance in the malaria vector Anopheles funestus in South West Nigeria.
abstract: BACKGROUND
  Knowing the extent and spread of insecticide resistance in malaria vectors is vital to successfully manage insecticide resistance in Africa. This information in the main malaria vector, Anopheles funestus sensu stricto, is completely lacking in the most populous country in Africa, Nigeria. This study reports the insecticide susceptibility status and the molecular basis of resistance of An. funestus as well as its involvement in malaria transmission in Akaka-Remo, a farm settlement village in southwest Nigeria.
  
  
  RESULTS
  Plasmodium infection analysis using TaqMan protocol coupled with a nested PCR revealed an infection rate of 8% in An. funestus s.s. from Akaka-Remo. WHO susceptibility tests showed this species has developed multiple resistance to insecticides in the study area. Anopheles funestus s.s. population in Akaka-Remo is highly resistant to organochlorines: dieldrin (8%) and DDT (10%). Resistance was also observed against pyrethroids: permethrin (68%) and deltamethrin (87%), and the carbamate bendiocarb (84%). Mortality rate with DDT slightly increased (from 10 to 30%, n = 45) after PBO pre-exposure indicating that cytochrome P450s play little role in DDT resistance while high mortalities were recorded after PBO pre-exposure with permethrin (from 68 to 100%, n = 70) and dieldrin (from 8 to 100%, n = 48) suggesting the implication of P450s in the observed permethrin and dieldrin resistance. High frequencies of resistant allele, 119F in F0(77%) and F1(80% in resistant and 72% in susceptible) populations with an odd ratio of 1.56 (P = 0.1859) show that L119F-GSTe2 mutation is almost fixed in the population. Genotyping of the A296S-RDL mutation in both F0and F1samples shows an association with dieldrin resistance with an odd ratio of 81 (P < 0.0001) (allelic frequency (R) = 76% for F0; for F1, 90 and 10% were observed in resistant and susceptible populations, respectively) as this mutation is not yet fixed in the population.
  
  
  CONCLUSIONS
  The study reports multiple insecticide resistance in An. funestus from Akaka Remo. It is, therefore, necessary to pay more attention to this major malaria vector for effective malaria control in Nigeria.
authors.affiliation: International Institute of Tropical Agriculture, 08 BP 0932, Cotonou, Benin. r.djouaka@cgiar.org.
authors.forename: Rousseau J
authors.identifier: http://orcid.org/0000-0002-0780-9131
authors.initials: RJ
authors.lastname: Djouaka
authors.affiliation: International Institute of Tropical Agriculture, 08 BP 0932, Cotonou, Benin.|Cell Biology and Genetics Unit, Department of Zoology, University of Ibadan, Ibadan, Oyo State, Nigeria.
authors.forename: Seun M
authors.initials: SM
authors.lastname: Atoyebi
authors.affiliation: International Institute of Tropical Agriculture, 08 BP 0932, Cotonou, Benin.|University of Abomey Calavi, BP 526, Cotonou, Benin.
authors.forename: Genevieve M
authors.initials: GM
authors.lastname: Tchigossou
authors.affiliation: Liverpool School of Tropical Medicine, Pembroke Place, Liverpool, L3 5QA, UK.
authors.forename: Jacob M
authors.initials: JM
authors.lastname: Riveron
authors.affiliation: Liverpool School of Tropical Medicine, Pembroke Place, Liverpool, L3 5QA, UK.
authors.forename: Helen
authors.initials: H
authors.lastname: Irving
authors.affiliation: International Institute of Tropical Agriculture, 08 BP 0932, Cotonou, Benin.|University of Abomey Calavi, BP 526, Cotonou, Benin.
authors.forename: Romaric
authors.initials: R
authors.lastname: Akoton
authors.affiliation: International Institute of Tropical Agriculture, 08 BP 0932, Cotonou, Benin.
authors.forename: Michael O
authors.initials: MO
authors.lastname: Kusimo
authors.affiliation: Cell Biology and Genetics Unit, Department of Zoology, University of Ibadan, Ibadan, Oyo State, Nigeria.
authors.forename: Adekunle A
authors.initials: AA
authors.lastname: Bakare
authors.affiliation: Liverpool School of Tropical Medicine, Pembroke Place, Liverpool, L3 5QA, UK.
authors.forename: Charles S
authors.initials: CS
authors.lastname: Wondji
mesh_terms: D000818:Animals; D000852:Anopheles / Q000187:drug effects* / Q000469:parasitology*; D001681:Biological Assay; D004026:Dieldrin / Q000494:pharmacology; D005260:Female; D005787:Gene Frequency; D005838:Genotype; D019476:Insect Proteins / Q000235:genetics; D007305:Insecticide Resistance; D007306:Insecticides / Q000494:pharmacology*; D008297:Male; D000072138:Mosquito Vectors / Q000187:drug effects*; D009154:Mutation; D009549:Nigeria; D026023:Permethrin / Q000494:pharmacology; D048448:Phenylcarbamates / Q000494:pharmacology; D010961:Plasmodium / Q000302:isolation & purification*; D016133:Polymerase Chain Reaction; D012424:Rural Population; D016019:Survival Analysis
chemical_list: D019476:Insect Proteins; D007306:Insecticides; D048448:Phenylcarbamates; D026023:Permethrin; D004026:Dieldrin; C007725:bendiocarb
keywords: Anopheles funestus; Insecticide resistance; Malaria control; Nigeria; Resistance mechanisms