Ecologists at the Centre for Ecology and Hydrology (CEH) have led a study on strategies for controlling midge-borne diseases such as bluetongue and Schmallenberg virus.
Doctors Steven White and Bethan Purse led a team of scientists to devise a scientific model explaining the appearance, disappearance and peak numbers of adult midges in the UK, on the basis of temperature effects on their survival and development.
Working in collaboration with scientists at The Pirbright Institute in Surrey and Rothamsted Research in Hertfordshire, the model integrated lab data linking temperature to demography and was tested out on year-round, daily captures of midges.
Because the model incorporates the biology underlying the seasonal patterns, it could then be used to simulate the impact of applying insecticides to adult midge populations at different times of year.
The results suggest the timings of insecticide treatments could be crucial in midge and disease control.
Spring midge peak
The results suggest treatments in the spring midge peak could inadvertently increase the midge abundance later in the year, due to a “density-dependence release effect” (adult removal leads to a decrease in overcompensatory larval competition, and increases larval survival and subsequent adult abundance).
Conversely, the model predicts timing insecticide treatments over the autumn midge peak has the greatest effect on population suppression.
The scientists, who presented their findings in Parasites and Vectors, said more extensive modelling of Culicoides biting midges in different countries will help create better ways to control them with insecticides, as well as predict instances of potential disease outbreaks.