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The ecology and control of Culicoides : potential vectors of bluetongue and African horse sickness in Northern Ireland

Culicoides midges are important haematophagous insects. Their principal significance is as vectors of> 75 diseases worldwide. Surveillance over a four-year period using Onderstepoort UV-light traps, found that Culicoides Obsolelus and Pulicaris groups dominated the species assemblage in Northern Ireland, at 74.8% and 20.7% of the total catch, respectively. Should a Culicoides vectored disease be introduced into Northern Ireland during the vector active period (early April to mid December), there are ample potential vectors to enable disease transmission. Principal Component Analysis of habitats surrunding trap locations confirmed that Culicoides abundance was positively correlated to characteristics of a livestock-rearing farm, whilst negatively correlated to arable and non-vegetated land. There was no significant difference between numbers pf Obsoletus Culicoides trapped outdoors or within cattle housing. However, fewer Pulicaris group Culicoides were captured in indoor compared to outdoor traps. Obsoletus group Culicoides breed mostly in cattle dung, whilst most Pulicaris group emerged from sheep dung. Cattle slurry and on-farm middens were also identified as suitable breeding sites for Obsoletus group Culicoides, although emergence from these substrates was sporadic. Culicoides alighting on farm livestock were mostly Obsoletus and Pulicaris groups, representing 92.0% and 7.7% of all Culicoides captured, respectively. Pulicaris group Culicoides had an intrinsic attraction to sheep when compared with cattle on a per liveweight basis. However, there was no evidence to suggest that Obsoletus group Culicoides fed preferentially on cattle over sheep, suggesting that this group is prone to opportunistic host seeking behaviour. Visual cues played a significant role in the host seeking behaviour of Obsoletus group Culicoides, with white and clear traps more attractive than yellow or blue.

Identiferoai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:676610
Date January 2014
CreatorsThompson, Geoffrey Michael
PublisherQueen's University Belfast
Source SetsEthos UK
Detected LanguageEnglish
TypeElectronic Thesis or Dissertation

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