title: Multiple insecticide resistances in the disease vector Culex p. quinquefasciatus from Western Indian Ocean.
abstract: Several mosquito-borne diseases affect the Western Indian Ocean islands. Culex pipiens quinquefasciatus is one of these vectors and transmits filariasis, Rift Valley and West Nile viruses and the Japanese encephalitis. To limit the impact of these diseases on public health, considerable vector control efforts have been implemented since the 50s, mainly through the use of neurotoxic insecticides belonging to Organochlorines (OC), Organophosphates (OP) and pyrethroids (PYR) families. However, mosquito control failures have been reported on site, and they were probably due to the selection of resistant individuals in response to insecticide exposure. In this study, we used different approaches to establish a first regional assessment of the levels and mechanisms of resistance to various insecticides. Bioassays were used to evaluate resistance to various insecticides, enzyme activity was measured to assess the presence of metabolic resistances through elevated detoxification, and molecular identification of known resistance alleles was investigated to determine the frequency of target-site mutations. These complementary approaches showed that resistance to the most used insecticides families (OC, OP and PYR) is widespread at a regional scale. However, the distribution of the different resistance genes is quite heterogeneous among the islands, some being found at high frequencies everywhere, others being frequent in some islands and absent in others. Moreover, two resistance alleles displayed clinal distributions in Mayotte and La Réunion, probably as a result of a heterogeneous selection due to local treatment practices. These widespread and diverse resistance mechanisms reduce the capacity of resistance management through classical strategies (e.g. insecticide rotation). In case of a disease outbreak, it could undermine the efforts of the vector control services, as only few compounds could be used. It thus becomes urgent to find alternatives to control populations of Cx. p. quinquefasciatus in the Indian Ocean.
authors.affiliation: Institut de recherche pour le développement, Unité Mixte de Recherche MIVEGEC (IRD 224-CNRS 5290-UM1-UM2), Montpellier, France.
authors.forename: Nicolas
authors.initials: N
authors.lastname: Pocquet
authors.forename: Pascal
authors.initials: P
authors.lastname: Milesi
authors.forename: Patrick
authors.initials: P
authors.lastname: Makoundou
authors.forename: Sandra
authors.initials: S
authors.lastname: Unal
authors.forename: Betty
authors.initials: B
authors.lastname: Zumbo
authors.forename: Célestine
authors.initials: C
authors.lastname: Atyame
authors.forename: Frédéric
authors.initials: F
authors.lastname: Darriet
authors.forename: Jean-Sébastien
authors.initials: JS
authors.lastname: Dehecq
authors.forename: Julien
authors.initials: J
authors.lastname: Thiria
authors.forename: Ambicadutt
authors.initials: A
authors.lastname: Bheecarry
authors.forename: Diana P
authors.initials: DP
authors.lastname: Iyaloo
authors.forename: Mylène
authors.initials: M
authors.lastname: Weill
authors.forename: Fabrice
authors.initials: F
authors.lastname: Chandre
authors.forename: Pierrick
authors.initials: P
authors.lastname: Labbé
mesh_terms: D000818:Animals; D003465:Culex / Q000187:drug effects* / Q000201:enzymology / Q000235:genetics; D004199:Disease Vectors; D017344:Genes, Insect / Q000235:genetics*; D006801:Humans; D019156:Indian Ocean; D007303:Insect Vectors / Q000235:genetics*; D007305:Insecticide Resistance / Q000235:genetics*; D007306:Insecticides / Q000494:pharmacology*; D009032:Mosquito Control
chemical_list: D007306:Insecticides