Fears climate is right for disease on wings of deadly insect

The Asian tiger mosquito, Aedes albopictus, has already been reported in France and Belgium and could be migrating north as winters become warmer and wetter.

Scientists are urging ‘wide surveillance’ for the biting insect across countries of central and northern Europe, including in Britain. The insect, which has silvery white bands on its legs and thorax, is expert at adapting to different environmental conditions. Previously found solely in moist, leafy tree holes, colonisation of man-made containers enabled its expansion into urban areas, and it can carry dengue and chikungunya viruses, both of which cause high fevers. The infections usually occur in tropical regions of Africa, Asia and South America.

Now scientists led by Dr Cyril Caminade from the University of Liverpool have used climate models to predict how changing conditions might affect Asian tiger mosquito distribution.

Writing in the Journal of the Royal Society Interface they report that: “Mosquito climate suitability has significantly increased over the southern UK, northern France, the Benelux, parts of Germany, Italy, Sicily and the Balkan countries.”

The research shows that parts of the UK could become hot-spots of Asian tiger mosquito activity between 2030 and 2050.

It has been introduced into Europe from Asia via goods shipments, mainly through used tyres and bamboo.

Climate change is now shifting conditions suitable for the insect from southern Europe to central north-western areas. The mosquito could survive in water butts and vases, and may find winter protection in greenhouses, say the researchers.

The current climate in the UK is considered too cold for dengue transmission, but because this mosquito has been involved in the trasmission of viruses in North America, precautions are necessary.

They wrote: “Effort should be made to conduct surveys for A. albopictus in countries that are described as high risk for its future establishment, and we also highly encourage a wide surveillance for this invasive species at the European level.”

The Health Protection Agency, which collaborated in the research, carries out regular checks including trapping insects and sampling larvae found in goods imported via UK ports including Hull and Goole. The agency also monitors tyre importing companies, many of which receive goods from South America.

“Constant surveillance both of the distribution of our native species and of any new species is necessary,” says entomologist Jolyon Medlock. “The Asian tiger mosquito, which travelled from an Indian Ocean island to Italy, has shown that it can evolve and cope in more a temperate climate. Being an island doesn’t make us completely immune because of the way goods and materials are carried around the world.”

Where there’s an accumulation of still water like a pond or a lidless water butt, there will be mosquitoes (we often call them gnats), says Medlock. Generally they are a low-level nuisance, except when they get out of hand through an event like the 2007 floods in East Yorkshire, which attracted many more mosquitoes to the area. But we can all take a few preventative measures.

“Keep the lid on the water butt, and don’t leave children’s toys and empty containers around in the garden to accumulate leaves and water. Mosquitoes like nothing better,” says the man who knows.

The HPA relies on the public to help collect mosquitoes and find out wher they are.

Mosquitos collected from different places should be placed in separate labelled containers. If more than one mosquito is collected from the same habitat on the same day, they may be sent in one container.

Live mosquitoes should be placed in a container and put in the freezer for 10 minutes to kill them. They should then be sent as soon as possible to the address below, with the completed data form from the HPA website.

Send samples in a small, crush-proof, plastic container (plastic vials can be supplied on request to the address or email below) to: Mosquito Recording Scheme, Medical Entomology and Zoonoses Ecology, Microbial Risk Assessment, Health Protection Agency, Porton Down, Salisbury, SP4 0JG. Email: [email protected] Website www.hpa.org.uk