title: Anopheles coluzzii larval habitat and insecticide resistance in the island area of Manoka, Cameroon.
abstract: The effectiveness of Long-Lasting Insecticidal Nets and Indoor Residual Spraying in malaria vector control is threatened by vector resistance to insecticides. Knowledge of mosquito habitats and patterns of insecticide resistance would facilitate the development of appropriate vector control strategies. Therefore, we investigated An. coluzzii larval habitats and resistance to insecticides in the Manoka rural island area compared with the Youpwe suburban inland area, in Douala VI and II districts respectively.
  
  
  
  Anopheline larvae and pupae were collected from open water bodies in December 2013 and April 2014 and reared until adult emergence. Two to four day old emerging females were morphologically identified as belonging to the An. gambiae complex and used for WHO susceptibility tests with 4 % DDT, 0.75 % permethrin, and 0.05 % deltamethrin, with or without piperonyl butoxide (PBO) synergist. Control and surviving specimens were identified down to the species using a PCR-RFLP method. Survivors were genotyped for kdr L1014 mutations using Hot Oligonucleotide Ligation Assay.
  
  
  
  In both study sites, ponds, residual puddles, boats, and drains were identified as the major An. gambiae s.l. larval habitats. A total of 1397 females, including 784 specimens from Manoka and 613 from Youpwe, were used for resistance testing. The two mosquito populations displayed resistance to DDT, permethrin and deltamethrin, with variable mortality rates from 1 % to 90 %. The knock-down times were also significantly increased (at least 2.8 fold). Pre-exposure of mosquitoes to PBO did not impact on their mortality to DDT, conversely the mortality rates to permethrin and deltamethrin were significantly increased (7.56 ≤ X(2) ≤ 48.63, df = 1, p < 0.01), suggesting involvement of P450 oxidases in pyrethroid resistance. A subsample of 400 An. gambiae s.l. specimens including 280 control and 120 survivors from bioassays were all found to be An. coluzzii species. Only the kdr 1014 F mutation was found in survivors, with 88.5 % (N = 76) and 75 % (N = 44) frequencies in Youpwe and Manoka respectively.
  
  
  
  This is the first report of An. coluzzii resistance to insecticides in an insular area in Cameroon. Since permanent larval habitats have been identified, larval source management strategies may be trialed in this area as complementary vector control interventions.
authors.affiliation: Institut de Recherche de Yaoundé (IRY), Organisation de Coordination pour la lutte contre les Endémies en Afrique Centrale (OCEAC), B.P. 288, Yaoundé, Cameroun. josyet2@gmail.com.|Biological Sciences Unit, Faculty of Medicine and Pharmaceutical Sciences, University of Douala, P.O.Box 2701, Douala, Cameroon. josyet2@gmail.com.
authors.forename: Josiane
authors.initials: J
authors.lastname: Etang
authors.affiliation: Laboratory of Animal Biology and Physiology, Faculty of Science, University of Douala, P.O.Box 24157, Douala, Cameroon.
authors.forename: Arthur
authors.initials: A
authors.lastname: Mbida Mbida
authors.affiliation: Laboratory of Animal Biology and Physiology, Faculty of Science, University of Douala, P.O.Box 24157, Douala, Cameroon.
authors.forename: Patrick
authors.initials: P
authors.lastname: Ntonga Akono
authors.affiliation: Laboratory of Animal Biology and Physiology, Faculty of Science, University of Douala, P.O.Box 24157, Douala, Cameroon.
authors.forename: Jerome
authors.initials: J
authors.lastname: Binyang
authors.affiliation: Biological Sciences Unit, Faculty of Medicine and Pharmaceutical Sciences, University of Douala, P.O.Box 2701, Douala, Cameroon.|Pôle d'Excellence en Epidémiologie du Paludisme, Service d'Epidémiologie et de Santé Publique, Centre Pasteur du Cameroun, B.P. 1274, Yaoundé, Cameroun.
authors.forename: Carole Else
authors.initials: CE
authors.lastname: Eboumbou Moukoko
authors.affiliation: Laboratory of Animal Biology and Physiology, Faculty of Science, University of Douala, P.O.Box 24157, Douala, Cameroon.
authors.forename: Leopold Gustave
authors.initials: LG
authors.lastname: Lehman
authors.affiliation: Institut de Recherche de Yaoundé (IRY), Organisation de Coordination pour la lutte contre les Endémies en Afrique Centrale (OCEAC), B.P. 288, Yaoundé, Cameroun.
authors.forename: Parfait
authors.initials: P
authors.lastname: Awono-Ambene
authors.affiliation: Laboratory of Animal Biology and Physiology, Faculty of Science, University of Douala, P.O.Box 24157, Douala, Cameroon.
authors.forename: Abdou
authors.initials: A
authors.lastname: Talipouo
authors.affiliation: Institut de Recherche de Yaoundé (IRY), Organisation de Coordination pour la lutte contre les Endémies en Afrique Centrale (OCEAC), B.P. 288, Yaoundé, Cameroun.|Laboratory of Animal Biology and Physiology, Faculty of Science, University of Douala, P.O.Box 24157, Douala, Cameroon.
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Ekoko Eyisab
authors.affiliation: Laboratory of Animal Biology and Physiology, Faculty of Science, University of Douala, P.O.Box 24157, Douala, Cameroon.
authors.forename: Darus
authors.initials: D
authors.lastname: Tagne
authors.affiliation: Laboratory of Animal Biology and Physiology, Faculty of Science, University of Douala, P.O.Box 24157, Douala, Cameroon.
authors.forename: Romeo
authors.initials: R
authors.lastname: Tchoffo
authors.affiliation: World Health Organization, Regional office for Africa, P.O.Box 6, Cité Djoué, Brazzaville, Congo.
authors.forename: Lucien
authors.initials: L
authors.lastname: Manga
authors.affiliation: Laboratory of General Biology, University of Yaounde I, P.O.Box 812, Yaounde, Cameroon.
authors.forename: Remy
authors.initials: R
authors.lastname: Mimpfoundi
mesh_terms: D000818:Animals; D000852:Anopheles / Q000187:drug effects* / Q000235:genetics*; D002163:Cameroon; D017753:Ecosystem; D005260:Female; D005787:Gene Frequency; D005838:Genotype; D007305:Insecticide Resistance / Q000187:drug effects* / Q000235:genetics; D007306:Insecticides / Q000494:pharmacology*; D062312:Islands; D007814:Larva / Q000187:drug effects; D009154:Mutation; D009570:Nitriles / Q000494:pharmacology; D026023:Permethrin / Q000494:pharmacology; D012150:Polymorphism, Restriction Fragment Length; D011679:Pupa / Q000187:drug effects; D011722:Pyrethrins / Q000494:pharmacology
chemical_list: D007306:Insecticides; D009570:Nitriles; D011722:Pyrethrins; C017180:decamethrin; D026023:Permethrin
keywords: Africa; Cameroon; Ecology; Insecticide resistance; Integrated vector management; Island; Malaria; Mosquitoes