Culicoides species composition and abundance on Irish cattle farms: implications for arboviral disease transmission

Áine B. Collins,Michael L. Doherty,Damien J. Barrett,Marion E. England,John F. Mee

doi:10.1186/s13071-018-3010-6

Áine B. Collins, Michael L. Doherty + Show 3 more

Open Access

https://doi.org/10.1186/s13071-018-3010-6

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Abstract

BackgroundFollowing the emergence of Schmallenberg virus (SBV) in Ireland in 2012, a sentinel herd surveillance program was established in the south of Ireland with the primary aim of investigating the species composition and abundance of Culicoides on livestock farms in the region.MethodsUltraviolet-light trapping for Culicoides was carried out on 10 sentinel farms. Each site was sampled fortnightly over 16 weeks (21st July to 5th November 2014). One Onderstepoort Veterinary Institute UV light trap was run overnight at each site and catches were transferred immediately into 70% ethanol. Culicoides were morphologically identified to species level. Collection site habitats were characterised using the Phase 1 habitat survey technique (Joint Nature Conservation Committee).ResultsA total of 23,929 individual Culicoides from 20 species was identified, including one species identified in Ireland for the first time, Culicoides cameroni. The most abundant species identified were Culicoides obsoletus/Culicoides scoticus (38%), Culicoides dewulfi (36%), Culicoides pulicaris (9%), Culicoides chiopterus (5%) and Culicoides punctatus (5%), comprising 93% of all Culicoides specimens identified. Collection site habitats were dominated by improved grassland and a combination of broadleaf woodland and native woodland species.ConclusionsThe most abundant species of Culicoides identified were the putative vectors of bluetongue virus (BTV) and SBV in northern Europe. Their presence and abundance demonstrates the potential for future transmission of arboviruses among livestock in this region.

Highlights

Following the emergence of Schmallenberg virus (SBV) in Ireland in 2012, a sentinel herd surveillance program was established in the south of Ireland with the primary aim of investigating the species composition and abundance of Culicoides on livestock farms in the region
The most abundant Culicoides species identified in the present study (C. obsoletus/C. scoticus, C. chiopterus, C. dewulfi, C. pulicaris and C. punctatus) are the putative vectors of bluetongue virus (BTV) and SBV in northern Europe
In the context of BTV, SBV and other exotic arboviruses, continued monitoring of the dynamics of Culicoides biting midges on farms in Ireland is recommended, considering the apparent change in the Culicoides species composition and abundance in the south of Ireland since 2009 and the on-going threat of a possible incursion of BTV-infected Culicoides from Europe

Summary

Introduction

Following the emergence of Schmallenberg virus (SBV) in Ireland in 2012, a sentinel herd surveillance program was established in the south of Ireland with the primary aim of investigating the species composition and abundance of Culicoides on livestock farms in the region. Culicoides biting midges have been implicated in the transmission of over 50 arboviruses worldwide [1] including bluetongue virus (BTV; Orbivirus, Reoviridae), Schmallenberg virus (SBV; Orthobunyavirus, Peribunyaviridae) and African. Since 1998, there have been regular outbreaks of bluetongue disease in many parts of southern Europe with the Afro-Asiatic species, Culicoides imicola, implicated. BTV-8 re-emerged in France in 2015 [7] and outbreaks of bluetongue disease continue to occur in domestic livestock in France [8].

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