title: Malaria vectors resistance to insecticides in Benin: current trends and mechanisms involved.
abstract: BACKGROUND
  Insecticides are widely used to control malaria vectors and have significantly contributed to the reduction of malaria-caused mortality. In addition, the same classes of insecticides were widely introduced and used in agriculture in Benin since 1980s. These factors probably contributed to the selection of insecticide resistance in malaria vector populations reported in several localities in Benin. This insecticide resistance represents a threat to vector control tool and should be monitored. The present study reveals observed insecticide resistance trends in Benin to help for a better management of insecticide resistance.
  
  
  METHODS
  Mosquito larvae were collected in eight sites and reared in laboratory. Bioassays were conducted on the adult mosquitoes upon the four types of insecticide currently used in public health in Benin. Knock-down resistance, insensitive acetylcholinesterase-1 resistance, and metabolic resistance analysis were performed in the mosquito populations based on molecular and biochemical analysis. The data were mapped using Geographical Information Systems (GIS) with Arcgis software.
  
  
  RESULTS
  Mortalities observed with Deltamethrin (pyrethroid class) were less than 90% in 5 locations, between 90-97% in 2 locations, and over 98% in one location. Bendiocarb (carbamate class) showed mortalities ranged 90-97% in 2 locations and were over 98% in the others locations. A complete susceptibility to Pirimiphos methyl and Fenitrothion (organophosphate class) was observed in all locations with 98-100% mortalities. Knock-down resistance frequencies were high (0.78-0.96) and similar between Anopheles coluzzii, Anopheles gambiae, Anopheles arabiensis, and Anopheles melas. Insensitive acetylcholinesterase-1 was rare (0.002-0.1) and only detected in Anopheles gambiae in concomitance with Knock-down resistance mutation. The maps showed a large distribution of Deltamethrin resistance, Knock-down mutation and metabolic resistance throughout the country, a suspected resistance to Bendiocarb and detection of insensitive acetylcholinesterase-1 from northern Benin, and a wide distribution of susceptible vectors to Pirimiphos methyl and Fenitrothion.
  
  
  CONCLUSIONS
  This study showed a widespread resistance of malaria vectors to pyrethroid previously located in southern Benin, an early emergence of carbamates resistance from northern Benin and a full susceptibility to organophosphates. Several resistance mechanisms were detected in vectors with a potential cross resistance to pyrethroids through Knock-down and metabolic resistance mechanisms.
authors.affiliation: Centre de Recherche Entomologique de Cotonou (CREC), Cotonou, Benin. amerusangel@yahoo.fr.|Faculté des Sciences et Techniques de l'Université d'Abomey-Calavi, Abomey-Calavi, Benin. amerusangel@yahoo.fr.
authors.forename: Virgile
authors.initials: V
authors.lastname: Gnanguenon
authors.affiliation: Centre de Recherche Entomologique de Cotonou (CREC), Cotonou, Benin. rofargossa@yahoo.fr.|Faculté des Sciences et Techniques de l'Université d'Abomey-Calavi, Abomey-Calavi, Benin. rofargossa@yahoo.fr.
authors.forename: Fiacre R
authors.initials: FR
authors.lastname: Agossa
authors.affiliation: Centre de Recherche Entomologique de Cotonou (CREC), Cotonou, Benin. kefilathbadirou@yahoo.fr.|Faculté des Sciences et Techniques de l'Université d'Abomey-Calavi, Abomey-Calavi, Benin. kefilathbadirou@yahoo.fr.
authors.forename: Kefilath
authors.initials: K
authors.lastname: Badirou
authors.affiliation: Centre de Recherche Entomologique de Cotonou (CREC), Cotonou, Benin. renaud292@yahoo.fr.|Faculté des Sciences et Techniques de l'Université d'Abomey-Calavi, Abomey-Calavi, Benin. renaud292@yahoo.fr.
authors.forename: Renaud
authors.initials: R
authors.lastname: Govoetchan
authors.affiliation: Centre de Recherche Entomologique de Cotonou (CREC), Cotonou, Benin. rodrigue.anagonou@yahoo.fr.|Faculté des Sciences et Techniques de l'Université d'Abomey-Calavi, Abomey-Calavi, Benin. rodrigue.anagonou@yahoo.fr.
authors.forename: Rodrigue
authors.initials: R
authors.lastname: Anagonou
authors.affiliation: Centre de Recherche Entomologique de Cotonou (CREC), Cotonou, Benin. fredook15@yahoo.fr.
authors.forename: Fredéric
authors.initials: F
authors.lastname: Oke-Agbo
authors.affiliation: Centre de Recherche Entomologique de Cotonou (CREC), Cotonou, Benin. roseric_2000@yahoo.fr.
authors.forename: Roseric
authors.initials: R
authors.lastname: Azondekon
authors.affiliation: Centre de Recherche Entomologique de Cotonou (CREC), Cotonou, Benin. ramloving@yahoo.fr.|Faculté des Sciences et Techniques de l'Université d'Abomey-Calavi, Abomey-Calavi, Benin. ramloving@yahoo.fr.
authors.forename: Ramziath
authors.initials: R
authors.lastname: AgbanrinYoussouf
authors.affiliation: Centre de Recherche Entomologique de Cotonou (CREC), Cotonou, Benin. ermyon2012@yahoo.fr.|Faculté des Sciences et Techniques de l'Université d'Abomey-Calavi, Abomey-Calavi, Benin. ermyon2012@yahoo.fr.
authors.forename: Roseline
authors.initials: R
authors.lastname: Attolou
authors.affiliation: Programme National de Lutte contre le Paludisme, Cotonou, Benin. filemont@yahoo.fr.
authors.forename: Filemon T
authors.initials: FT
authors.lastname: Tokponnon
authors.affiliation: Centre de Recherche Entomologique de Cotonou (CREC), Cotonou, Benin. rockypremier@yahoo.fr.|Faculté des Sciences et Techniques de l'Université d'Abomey-Calavi, Abomey-Calavi, Benin. rockypremier@yahoo.fr.
authors.forename: Rock
authors.initials: R
authors.lastname: Aïkpon
authors.affiliation: Centre de Recherche Entomologique de Cotonou (CREC), Cotonou, Benin. ossraz@yahoo.fr.|Université d'Agriculture de Kétou, Kétou, Benin. ossraz@yahoo.fr.
authors.forename: Razaki
authors.initials: R
authors.lastname: Ossè
authors.affiliation: Centre de Recherche Entomologique de Cotonou (CREC), Cotonou, Benin. akogbetom@yahoo.fr.|Faculté des Sciences et Techniques de l'Université d'Abomey-Calavi, Abomey-Calavi, Benin. akogbetom@yahoo.fr.
authors.forename: Martin C
authors.initials: MC
authors.lastname: Akogbeto
mesh_terms: D000818:Animals; D000852:Anopheles / Q000187:drug effects*; D001541:Benin; D001681:Biological Assay; D005843:Geography; D007303:Insect Vectors / Q000187:drug effects*; D007305:Insecticide Resistance; D007306:Insecticides / Q000494:pharmacology*; D007814:Larva / Q000187:drug effects; D016019:Survival Analysis
chemical_list: D007306:Insecticides