title: How do species, population and active ingredient influence insecticide susceptibility in Culicoides biting midges (Diptera: Ceratopogonidae) of veterinary importance?
abstract: BACKGROUND
  Culicoides biting midges are biological vectors of internationally important arboviruses of livestock and equines. Insecticides are often employed against Culicoides as a part of vector control measures, but systematic assessments of their efficacy have rarely been attempted. The objective of the present study is to determine baseline susceptibility of multiple Culicoides vector species and populations in Europe and Africa to the most commonly used insecticide active ingredients. Six active ingredients are tested: three that are based on synthetic pyrethroids (alpha-cypermethrin, deltamethrin and permethrin) and three on organophosphates (phoxim, diazinon and chlorpyrifos-methyl).
  
  
  METHODS
  Susceptibility tests were conducted on 29,064 field-collected individuals of Culicoides obsoletus Meigen, Culicoides imicola Kieffer and a laboratory-reared Culicoides nubeculosus Meigen strain using a modified World Health Organization assay. Populations of Culicoides were tested from seven locations in four different countries (France, Spain, Senegal and South Africa) and at least four concentrations of laboratory grade active ingredients were assessed for each population.
  
  
  RESULTS
  The study revealed that insecticide susceptibility varied at both a species and population level, but that broad conclusions could be drawn regarding the efficacy of active ingredients. Synthetic pyrethroid insecticides were found to inflict greater mortality than organophosphate active ingredients and the colony strain of C. nubeculosus was significantly more susceptible than field populations. Among the synthetic pyrethroids, deltamethrin was found to be the most toxic active ingredient for all species and populations.
  
  
  CONCLUSIONS
  The data presented represent the first parallel and systematic assessment of Culicoides insecticide susceptibility across several countries. As such, they are an important baseline reference to monitor the susceptibility status of Culicoides to current insecticides and also to assess the toxicity of new active ingredients with practical implications for vector control strategies.
authors: EID Méditerranée, 34184, Montpellier, France. rvenail@yahoo.com.
authors: Roger
authors: R
authors: Venail
authors: Cirad, UMR15 CMAEE; INRA, UMR1309 CMAEE, 34398, Montpellier, France. jonathanlhoir@hotmail.com.
authors: Jonathan
authors: J
authors: Lhoir
authors: Institut sénégalais de recherches agricoles (ISRA), BP 1386, Dakar, Senegal. moussafall08@yahoo.fr.
authors: Moussa
authors: M
authors: Fall
authors: Laboratory of Zoology, University of the Balearic Islands (UIB), Km 7.5, Palma de Mallorca, Spain. ricardo.delrio@uib.es.
authors: Ricardo
authors: R
authors: del Río
authors: Centre de Recerca en Sanitat Animal (CReSA), UAB-IRTA, Campus de la Universitat Autònoma de Barcelona, 08193, Bellaterra, Barcelona, Spain. sandra.talavera@cresa.uab.cat.
authors: Sandra
authors: S
authors: Talavera
authors: Agricultural Research Council - ARC- Onderstepoort Veterinary Institute, Private Bag X5, Onderstepoort, 0110, Republic of South Africa. labuschagnek@arc.agric.za.
authors: Karien
authors: K
authors: Labuschagne
authors: Laboratory of Zoology, University of the Balearic Islands (UIB), Km 7.5, Palma de Mallorca, Spain. ma.miranda@uib.es.
authors: Miguel
authors: M
authors: Miranda
authors: Centre de Recerca en Sanitat Animal (CReSA), UAB-IRTA, Campus de la Universitat Autònoma de Barcelona, 08193, Bellaterra, Barcelona, Spain. nitu.pages@cresa.uab.cat.
authors: Nonito
authors: N
authors: Pagès
authors: Agricultural Research Council - ARC- Onderstepoort Veterinary Institute, Private Bag X5, Onderstepoort, 0110, Republic of South Africa. VenterG@arc.agric.za.
authors: Gert
authors: G
authors: Venter
authors: Cirad, UMR15 CMAEE; INRA, UMR1309 CMAEE, 34398, Montpellier, France. ignace.rakotoarivony@cirad.fr.
authors: Ignace
authors: I
authors: Rakotoarivony
authors: Cirad, UMR15 CMAEE; INRA, UMR1309 CMAEE, 34398, Montpellier, France. xavier.allene@cirad.fr.
authors: Xavier
authors: X
authors: Allène
authors: EID Méditerranée, 34184, Montpellier, France. bethsabee.scheid@gmail.com.
authors: Bethsabée
authors: B
authors: Scheid
authors: Cirad, UMR15 CMAEE; INRA, UMR1309 CMAEE, 34398, Montpellier, France. laetitia.gardes@cirad.fr.
authors: Laëtitia
authors: L
authors: Gardès
authors: Cirad, UMR15 CMAEE; INRA, UMR1309 CMAEE, 34398, Montpellier, France. geoffrey.gimonneau@cirad.fr.|Institut sénégalais de recherches agricoles (ISRA), BP 1386, Dakar, Senegal. geoffrey.gimonneau@cirad.fr.
authors: Geoffrey
authors: G
authors: Gimonneau
authors: Cirad, UMR15 CMAEE; INRA, UMR1309 CMAEE, 34398, Montpellier, France. renaud.lancelot@cirad.fr.
authors: Renaud
authors: R
authors: Lancelot
authors: Cirad, UMR15 CMAEE; INRA, UMR1309 CMAEE, 34398, Montpellier, France. claire.garros@cirad.fr.
authors: Claire
authors: C
authors: Garros
authors: Cirad, UMR15 CMAEE; INRA, UMR1309 CMAEE, 34398, Montpellier, France. catherine.cetre-sossah@cirad.fr.
authors: Catherine
authors: C
authors: Cêtre-Sossah
authors: Cirad, UMR15 CMAEE; INRA, UMR1309 CMAEE, 34398, Montpellier, France. thomas.balenghien@cirad.fr.
authors: Thomas
authors: T
authors: Balenghien
authors: The Pirbright Institute, Vector-borne Viral Disease Programme, Woking, GU24 0NF, UK. simon.carpenter@pirbright.ac.uk.
authors: Simon
authors: S
authors: Carpenter
authors: Cirad, UMR15 CMAEE; INRA, UMR1309 CMAEE, 34398, Montpellier, France. thierry.baldet@cirad.fr.
authors: Thierry
authors: T
authors: Baldet
mesh_terms: D000349:Africa; D000818:Animals; D001681:Biological Assay; D002519:Ceratopogonidae / Q000145:classification* / Q000187:drug effects*; D005060:Europe; D007303:Insect Vectors / Q000145:classification / Q000187:drug effects; D007306:Insecticides / Q000494:pharmacology*; D010755:Organophosphates / Q000494:pharmacology; D021261:Parasitic Sensitivity Tests; D011722:Pyrethrins / Q000494:pharmacology; D016019:Survival Analysis
chemical_list: D007306:Insecticides; D010755:Organophosphates; D011722:Pyrethrins