Scotland's dreaded midges carrying previously unknown viruses
Scotland’s biting midge population carries previously-unknown viruses, according to research by the University of Glasgow.
The scientists who studied midgies collected within the Loch Lomond and Trossachs National Park, used high throughput sequencing to study, for the first time, the total collection of viruses in the biting midge (Culicoides impunctatus).
Researchers discovered several new viruses in the ‘virome’ - acids in a viral community - of the midges, including an alphanodavirus, two rhabdo-like viruses and a chuvirus.
These viruses are mainly found in insects and other invertebrates, but some members of the alphanodaviruses naturally infect pigs and herons, sometimes causing death.
However, there is currently no evidence that these viruses pose a threat to humans.
Despite their prevalence in Scotland, midges – small biting flies which are a predominantly a nuisance to humans – are currently understudied. Yet midges are carriers of arboviruses (viral infections transmitted to humans from a group of insects) and were responsible for the emergence and spread of Schmallenberg virus (SBV) in Europe in 2011, and are likely to be involved in the emergence of other arboviruses in Europe.
There are at least 41 different species of biting midge described in the UK, of which 37 are present in Scotland.
Lead author Sejal Modha said: “The technology we used allowed us to look at the viruses carried by midges in a way that can’t be done in the lab, expanding our knowledge of the insect viruses in a way that could be very useful in future.
“What we found is important because biting midges can be carriers of arboviruses; and although midges are not currently a public health concern in Scotland – and we stress there is nothing for the public to be concerned about – our research gives us a better understanding of midges and the viruses they may carry, helping us prepare for any possible future emerging risks through improved surveillance and knowledge.”
Co-author Joseph Hughes added: “What we found is the tip of the iceberg in terms of discovering new viruses. With an estimated 5.5 million insect species on Earth, there are likely to be several million more insect viruses to be discovered. What we are seeing globally, due to several factors including climate change, is the movement of virus vectors – or carriers – to new regions.
“Our research is important because the emergence of SBV in Europe, which is transmitted by biting midges, and the incursion of multiple strains of bluetongue virus into Europe, means we need to understand more about the diversity of viruses carried by biting midges. By increasing our understanding, we can hopefully be better prepared for viruses that may emerge in the midge population in future.”
The study, published in Viruses. is funded by the Medical Research Council.