Midge population dynamics for virus control
Bluetongue virus (BTV) can have devastating effects for the livestock industry. It causes severe losses financially and is a distressing condition for the animal concerned. Control of the disease is complex and the European project BLUETONGUE VACCINATION concentrated its resources on the development of an efficacious vaccine for the virus. Another angle of research came from partners at the Onderstepoort Veterinary Institute in South Africa. They investigated breeding sites and changes in population number for the primary vector, Culicoides imicola (C. imicola). They found that moisture content and the speed with which a location dries up were the two main factors responsible for abundance of the insect. However, another significant factor was that the midge appeared to be nomadic and could occupy temporary breeding sites. Populations could therefore readily transfer to more suitable areas when a site became too dry. The midge is most prevalent in hot humid conditions in the summer months. The team therefore initiated the establishment of a laboratory colony. This would mean that vector-host relationships could be studied all year round. Wild adult midges were collected and successfully induced to blood feed in the laboratory. Furthermore, their larvae survived together with the resulting adult progeny. A more in-depth understanding of the pathology of this disease is possible then if a sustainable laboratory population is set up. Research will therefore be able to continue in countries during the winter period or when the midge is absent for any reason.
