title: Local dispersal of palaearctic Culicoides biting midges estimated by mark-release-recapture.
abstract: BACKGROUND
  Farm to farm movement of Culicoides midges is believed to play a critical role in the spread of bluetongue (BT), Schmallenberg and other midge-borne diseases. To help understand and predict the spread of diseases carried by midges, there is a need to determine their dispersal patterns, and to identify factors contributing to the direction taken and distance travelled.
  
  
  METHODS
  The dispersal of Obsoletus Group members was studied on 19 farms around Bala, north Wales. Field-collected Culicoides were trapped in a black-light (OVI) trap and self-marked in the collecting vessel, using micronized fluorescent dust. Culicoides were released at a central farm and OVI traps set on 18 surrounding farms, at distances of 1 to 4 km. The study was repeated using six colours of fluorescent dust over an 18 day period.
  
  
  RESULTS
  An estimated 61,062 (95% CI = 56,298-65,830) marked Culicoides were released during the study and 12 (0.02%) Culicoides were recaptured. Of the females recaptured, six were C. obsoletus/scoticus, two C. dewulfi, two C. pulicaris and one C. festivipennis. The male was C. obsoletus. Recaptures occurred 1-2.5 km from the release site, with greatest numbers at 2.5 km. Most recaptures were 2 nights post-release; none were more than 3 nights post-release. Two females were recovered at 1.5 km on the night of release and one male at 1 km two nights post-release. The mean distance travelled (MDT) for males was 1 km, females was 2.21 km, and all recaptured Culicoides was 2.15 km. Recaptures were made both downwind and upwind of the prevailing wind direction during the trapping periods, highlighting possible passive and active dispersal of Culicoides between farms.
  
  
  CONCLUSIONS
  This is the first study to demonstrate farm to farm movement of the main Palaearctic BT vector species, the Obsoletus Group. Such movement has disease control implications in terms of the vectoral movement of disease between farms. The results suggest that Culicoides control measures applied at an infected farm (trapping or killing Culicoides) will reduce risk of spread to neighbouring farms by lessening the number of Culicoides dispersing from that farm, as well as reducing transmission at the source farm itself.
authors.affiliation: Institute of Infection and Global Health, Liverpool University Climate and Infectious Diseases of Animals (LUCINDA) Group, University of Liverpool, Leahurst Campus, Neston, Cheshire, UK. g.kluiters@liverpool.ac.uk.
authors.forename: Georgette
authors.initials: G
authors.lastname: Kluiters
authors.affiliation: Institute of Infection and Global Health, Liverpool University Climate and Infectious Diseases of Animals (LUCINDA) Group, University of Liverpool, Leahurst Campus, Neston, Cheshire, UK. H.Swales@liverpool.ac.uk.
authors.forename: Harry
authors.initials: H
authors.lastname: Swales
authors.affiliation: Institute of Infection and Global Health, Liverpool University Climate and Infectious Diseases of Animals (LUCINDA) Group, University of Liverpool, Leahurst Campus, Neston, Cheshire, UK. matthew.baylis@liverpool.ac.uk.|National Institute for Health Research, Health Protection Research Unit in Emerging and Zoonotic Infections, University of Liverpool, Neston, UK. matthew.baylis@liverpool.ac.uk.
authors.forename: Matthew
authors.initials: M
authors.lastname: Baylis
mesh_terms: D063147:Animal Distribution; D000818:Animals; D001819:Bluetongue / Q000453:epidemiology* / Q000821:virology; D002519:Ceratopogonidae / Q000502:physiology* / Q000821:virology; D004391:Dust; D005260:Female; D005456:Fluorescent Dyes; D007303:Insect Vectors / Q000502:physiology* / Q000821:virology; D008297:Male; D014852:Wales / Q000453:epidemiology
chemical_list: D004391:Dust; D005456:Fluorescent Dyes