Worldwide Niche and Future Potential Distribution of Culicoides imicola, a Major Vector of Bluetongue and African Horse Sickness Viruses

Abstract

We modelled the ecoclimatic niche of Culicoides imicola, a major arthropod vector of midge-borne viral pathogens affecting ruminants and equids, at fine scale and on a global extent, so as to provide insight into current and future risks of disease epizootics, and increase current knowledge of the species' ecology. Based on the known distribution and ecology of C. imicola, the species' response to monthly climatic conditions was characterised using CLIMEX with 10′ spatial resolution climatic datasets. The species' climatic niche was projected worldwide and under future climatic scenarios. The validated model highlights the role of irrigation in supporting the occurrence of C. imicola in arid regions. In Europe, the modelled potential distribution of C. imicola extended further West than its reported distribution, raising questions regarding ongoing process of colonization and non-climatic habitat factors. The CLIMEX model highlighted similar ecological niches for C. imicola and the Australasian C. brevitarsis raising questions on biogeography and biosecurity. Under the climate change scenarios considered, its' modelled potential distribution could expand northward in the Northern hemisphere, whereas in Africa its range may contract in the future. The biosecurity risks from bluetongue and African horse sickness viruses need to be re-evaluated in regions where the vector's niche is suitable. Under a warmer climate, the risk of vector-borne epizootic pathogens such as bluetongue and African horse sickness viruses are likely to increase as the climate suitability for C. imicola shifts poleward, especially in Western Europe.

Biotic and abiotic factors shape the microbiota of wild‐caught populations of the arbovirus vectorCulicoides imicola

“…In particular, Culicoides imicola Kieffer has been associated with the transmission of BTV in small ruminants and African horse sickness virus, which affects equids such as horses, mules, and donkeys (Purse et al, 2005). C. imicola's distribution was restricted to Africa and occasionally found in European Mediterranean countries (Purse et al, 2005;Venter et al, 1994), but it has been hypothesized that climate change in the last decades has extended their prevalence to other regions of the world (Acevedo et al, 2010;Guichard et al, 2014;Jacquet et al, 2015). How C. imicola has adapted to spread so quickly in different areas of Europe, Asia and Africa is not fully understood (Guichard et al, 2014;Jacquet et al, 2015).…”

African Horse Sickness Caused by Genome Reassortment and Reversion to Virulence of Live, Attenuated Vaccine Viruses, South Africa, 2004–2014

“…The virus is transmitted to horses by biting midges in the genus Culicoides ( 2 ). Although AHS currently occurs only in sub-Saharan Africa, various species of Culicoides midges occur throughout the entire inhabited world, warranting concern that AHSV could spread into areas that are currently free of the virus ( 1 , 3 – 5 ). Furthermore, the global range of related Culicoides -transmitted orbiviruses, such as bluetongue virus, has expanded recently, probably in part as a result of climate change ( 6 ).…”

The challenges posed by equine arboviruses

“…The distribution of the main vector of AHSV (Culicoides imicola) extends from South Africa to Southern Europe and across the Middle East to South East Asia and Southern China [62]. African horse sickness virus was introduced into Spain in 1987 when a group of zebra were brought by ship from Namibia and were quarantined outdoors near Madrid.…”