New research led by The Pirbright Institute and Queens University Belfast reveals that biting midges, the insects responsible for transmitting bluetongue virus, can survive much colder temperatures than previously thought, which may have implications for the overwintering of the virus.
Midges can transmit several economically devastating livestock diseases, including bluetongue virus, African horse sickness virus and Schallenberg virus.
The research, conducted in Pirbright’s Insectary, is published in the Journal of Medical Entomology, and is the first study to quantify cold tolerance across every life stage of Culicoides biting midges.
The study tested midges at all stages of their life cycle, from eggs to larvae, pupae and adults, under short and prolonged cold exposure. The results show that the eggs survived temperatures as low as -18 °C, the lowest temperature achievable with the experimental system, and may tolerate even colder conditions.
Dr Marion England, who leads the Vector Ecology group at The Pirbright Institute, where the study was conducted said:
“Identifying which life stages are most cold tolerant helps to explain how midges overwinter in northern Europe. We are currently experiencing an ongoing outbreak of bluetongue virus in the UK and this research provides insights into the survival potential of adult midges through the winter, with implications for virus overwintering.
“This research provides essential biological evidence to improve predictions of vector-borne disease and to strengthen climate-related disease risk models. The findings will help guide UK and European surveillance efforts and support government agencies and veterinary services in planning for future disease threats.”
Lead author of the study, Lucy Devlin, a PhD researcher from the School of Biological Sciences and Institute for Global Food Security at Queen’s, added:
“Our findings help explain how these midges can survive even in the coldest of months, and at temperatures lower than previously assumed.
“Our research is particularly timely as it follows the re-emergence of bluetongue across northern Europe in recent years, and its first recorded outbreak in Northern Ireland in late 2025, the first on the entire island.”
The virus primarily affects sheep, cattle, goats and camelids, with outbreaks resulting in livestock movement restrictions, trade disruption, animal welfare concerns, additional pressures on veterinary and animal health services, and economic losses to farmers.
This research, which was funded by the Department of Agriculture, Environment and Rural Affairs (DAERA), Northern Ireland, and Biotechnology and Biological Sciences Research Council (BBSRC), was a collaboration between Queen’s, The Pirbright Institute and the Agri-Food and Biosciences Institute (AFBI).
Read the paper:
Lucy M Devlin, Ross N Cuthbert, Melanie Nicholls, Archie K Murchie, Connor G G Bamford, Jaimie T A Dick, Eric R Morgan, Son T Mai, Marion England: Substantial cold tolerance in all life stages of Culicoides nubeculosus (Diptera: Ceratopogonidae)
Journal of Medical Entomology, Volume 63, Issue 1, January 2026, tjag020, https://doi.org/10.1093/jme/tjag020