title: Susceptibility profile and metabolic mechanisms involved in Aedes aegypti and Aedes albopictus resistant to DDT and deltamethrin in the Central African Republic.
abstract: Aedes aegypti and Ae. albopictus are the main epidemic vectors of dengue, chikungunya and Zika viruses worldwide. Their control during epidemics relies mainly on control of larvae and adults with insecticides. Unfortunately, loss of susceptibility of both species to several insecticide classes limits the efficacy of interventions. In Africa, where Aedes-borne viruses are of growing concern, few data are available on resistance to insecticides. To fill this gap, we assessed the susceptibility to insecticides of Ae. aegypti and Ae. albopictus populations in the Central African Republic (CAR) and studied the mechanisms of resistance.
  
  
  
  Immature stages were sampled between June and September 2014 in six locations in Bangui (the capital of CAR) for larval and adult bioassays according to WHO standard procedures. We also characterized DDT- and pyrethroid-resistant mosquitoes molecularly and biochemically, including tests for the activities of nonspecific esterases (α and β), mixed-function oxidases, insensitive acetylcholinesterase and glutathione S-transferases.
  
  
  
  Larval bioassays, carried out to determine the lethal concentrations (LC50and LC95) and resistance ratios (RR50and RR95), suggested that both vector species were susceptible to Bacillus thuringiensis var. israeliensis and to temephos. Bioassays of adults showed susceptibility to propoxur and fenitrothion, except for one Ae. albopictus population that was suspected to be resistant to fenithrothion. None of the Ae. aegypti populations was fully susceptible to DDT. Ae. albopictus presented a similar profile to Ae. aegypti but with a lower mortality rate (41%). Possible resistance to deltamethrin was observed among Ae. aegypti and Ae. albopictus, although some were susceptible. No kdr mutations were detected in either species; however, the activity of detoxifying enzymes was higher in most populations than in the susceptible Ae. aegypti strain, confirming decreased susceptibility to DDT and deltamethrin.
  
  
  
  These findings suggested that regular, continuous monitoring of resistance is necessary in order to select the most effective adulticides for arbovirus control in Bangui.
authors.affiliation: Institut Pasteur de Bangui, PO Box 923, Bangui, Central African Republic. ngoagounic@yahoo.fr.
authors.forename: Carine
authors.identifier: 0000-0002-2010-3758
authors.initials: C
authors.lastname: Ngoagouni
authors.affiliation: Research Unit Liverpool School of Tropical Medicine, Organisation de Coordination pour la lutte contre les Endémies en Afrique Centrale, PO Box 288, Yaoundé, Cameroon.
authors.forename: Basile
authors.initials: B
authors.lastname: Kamgang
authors.affiliation: Laboratoire des Maladies Infectieuses et Vecteurs: Ecologie, Génétique, Evolution et Contrôle, Unité mixte de Recherche 224-5290, Centre National de Recherche Scientifique-Institut de Recherche pour le Développement, Université de Montpellier, Montpellier, France.
authors.forename: Cécile
authors.initials: C
authors.lastname: Brengues
authors.affiliation: Laboratoire des Maladies Infectieuses et Vecteurs: Ecologie, Génétique, Evolution et Contrôle, Unité mixte de Recherche 224-5290, Centre National de Recherche Scientifique-Institut de Recherche pour le Développement, Université de Montpellier, Montpellier, France.
authors.forename: Gildas
authors.initials: G
authors.lastname: Yahouedo
authors.affiliation: Laboratoire des Maladies Infectieuses et Vecteurs: Ecologie, Génétique, Evolution et Contrôle, Unité mixte de Recherche 224-5290, Centre National de Recherche Scientifique-Institut de Recherche pour le Développement, Université de Montpellier, Montpellier, France.
authors.forename: Christophe
authors.initials: C
authors.lastname: Paupy
authors.affiliation: Institut Pasteur de Bangui, PO Box 923, Bangui, Central African Republic.
authors.forename: Emmanuel
authors.initials: E
authors.lastname: Nakouné
authors.affiliation: Institut Pasteur de Bangui, PO Box 923, Bangui, Central African Republic.|Institut Pasteur de la Guyane, BP 6010, 23 Avenue Pasteur, 97306, Cayenne, French Guiana.
authors.forename: Mirdad
authors.initials: M
authors.lastname: Kazanji
authors.affiliation: Laboratoire des Maladies Infectieuses et Vecteurs: Ecologie, Génétique, Evolution et Contrôle, Unité mixte de Recherche 224-5290, Centre National de Recherche Scientifique-Institut de Recherche pour le Développement, Université de Montpellier, Montpellier, France.
authors.forename: Fabrice
authors.initials: F
authors.lastname: Chandre
mesh_terms: D000330:Aedes / Q000187:drug effects*; D000818:Animals; D001681:Biological Assay; D002488:Central African Republic; D003634:DDT / Q000494:pharmacology*; D007305:Insecticide Resistance; D007306:Insecticides / Q000494:pharmacology*; D009570:Nitriles / Q000494:pharmacology*; D011722:Pyrethrins / Q000494:pharmacology*; D016019:Survival Analysis
chemical_list: D007306:Insecticides; D009570:Nitriles; D011722:Pyrethrins; C017180:decamethrin; D003634:DDT
keywords: Aedes aegypti; Aedes albopictus; Arboviruses; Central African Republic; Insecticide resistance; Metabolic resistance; Vectors