title: Can insecticide-treated netting provide protection for Equids from Culicoides biting midges in the United Kingdom?
abstract: BACKGROUND
  Biting midges of the genus Culicoides Latreille, 1809 (Diptera: Ceratopogonidae) cause a significant biting nuisance to equines and are responsible for the biological transmission of African horse sickness virus (AHSV). While currently restricted in distribution to sub-Saharan Africa, AHSV has a history of emergence into southern Europe and causes one of the most lethal diseases of horses and other species of Equidae. In the event of an outbreak of AHSV, the use of insecticide treated nets (ITNs) to screen equine accomodation is recommended by competent authorities including the Office International des Épizooties (OIE) in order to reduce vector-host contact.
  
  
  METHODS
  Seven commercially avaliable pyrethroid insecticides and three repellent compounds, all of which are licensed for amateur use, were assessed in modified World Health Organization (WHO) cone bioassay trials in the laboratory using a colony line of Culicoides nubeculosus (Meigen), 1830. Two field trials were subsequently conducted to test the efficiency of treated net screens in preventing entry of Culicoides.
  
  
  RESULTS
  A formulation of cypermethrin (0.15 % w/w) and pyrethrins (0.2 % w/w) (Tri-Tec 14®, LS Sales (Farnham) Ltd, Bloxham, UK) applied to black polyvinyl-coated polyester insect screen (1.6 mm aperture; 1.6 mm thickness) inflicted 100 % mortality on batches of C. nubeculosus following a three minute exposure in the WHO cone bioassays at 1, 7 and 14 days post-treatment. Tri-Tec 14® outperformed all other treatments tested and was subsequently selected for use in field trials. The first trial demonstrated that treated screens placed around an ultraviolet light-suction trap entirely prevented Culicoides being collected, despite their collection in identical traps with untreated screening or no screening. The second field trial examined entry of Culicoides into stables containing horses and found that while the insecticide treated screens reduced entry substantially, there was still a small risk of exposure to biting.
  
  
  CONCLUSIONS
  Screened stables can be utilised as part of an integrated control program in the event of an AHSV outbreak in order to reduce vector-host contact and may also be applicable to protection of horses from Culicoides during transport.
authors.affiliation: University of Surrey, Guildford, Surrey, GU2 7XH, UK. tadriman@btinternet.com.|Vector-borne Viral Diseases Programme, The Pirbright Institute, Ash Road, Pirbright, Surrey, GU24 0NF, UK. tadriman@btinternet.com.
authors.forename: Tiffany
authors.initials: T
authors.lastname: Baker
authors.affiliation: Vector-borne Viral Diseases Programme, The Pirbright Institute, Ash Road, Pirbright, Surrey, GU24 0NF, UK. simon.carpenter@pirbright.ac.uk.
authors.forename: Simon
authors.initials: S
authors.lastname: Carpenter
authors.affiliation: Vector-borne Viral Diseases Programme, The Pirbright Institute, Ash Road, Pirbright, Surrey, GU24 0NF, UK. simon.gubbins@pirbright.ac.uk.
authors.forename: Simon
authors.initials: S
authors.lastname: Gubbins
authors.affiliation: Animal Health Trust, Lanwades Park, Kentford, Newmarket, Suffolk, CB8 7UU, UK. richard.newton@aht.org.uk.
authors.forename: Richard
authors.initials: R
authors.lastname: Newton
authors.affiliation: Department of Veterinary Medicine, University of Cambridge, Madingley Road, Cambridge, CB3 0ES, UK. Gianni.Loiacono@phe.gov.uk.
authors.forename: Giovanni
authors.initials: G
authors.lastname: Lo Iacono
authors.affiliation: Department of Veterinary Medicine, University of Cambridge, Madingley Road, Cambridge, CB3 0ES, UK. jlnw2@cam.ac.uk.
authors.forename: James
authors.initials: J
authors.lastname: Wood
authors.affiliation: Vector-borne Viral Diseases Programme, The Pirbright Institute, Ash Road, Pirbright, Surrey, GU24 0NF, UK. lara.harrup@pirbright.ac.uk.
authors.forename: Lara Ellen
authors.initials: LE
authors.lastname: Harrup
mesh_terms: D000355:African Horse Sickness / Q000517:prevention & control*; D000356:African Horse Sickness Virus / Q000502:physiology*; D000818:Animals; D002519:Ceratopogonidae / Q000187:drug effects* / Q000821:virology; D004196:Disease Outbreaks / Q000517:prevention & control / Q000662:veterinary*; D005260:Female; D006736:Horses; D057148:Insecticide-Treated Bednets / Q000662:veterinary*; D007306:Insecticides / Q000494:pharmacology*; D008297:Male; D011722:Pyrethrins / Q000494:pharmacology*; D006113:United Kingdom / Q000453:epidemiology
chemical_list: D007306:Insecticides; D011722:Pyrethrins; C017160:cypermethrin