Insects such as wild bees and hoverflies are dying out in many parts of the the UK, and it could pose a threat to food we eat, researchers have found.
Between 1980 and 2013, a third of more than 300 species studied experienced population declines, while a smaller number (11%) became more abundant.
Scientists believe that the loss of biodiversity could pose problems in coming years.
Dr Gary Powney, from the Centre for Ecology and Hydrology in Wallingford, Oxfordshire, said:
‘While the increase in key crop pollinators is good news, they are still a relatively small group of species.
‘Therefore, with species having declined overall, it would be risky to rely on this group to support the long-term food security for our country.
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‘If anything happens to them in the future, there will be fewer other species to step up and fulfil the essential role of crop pollination.’
The value of pollinating insects to the UK economy has been estimated at £690 million per year.
While around 34% of pollination is carried out by honeybees, a scarcity of hives means crop farmers are highly reliant on their wild cousins and other insects, especially hoverflies.
The research is based on analysis of more than 715,000 observational records collected by volunteers between 1980 and 2013.
A total of 353 bee and hoverfly species, all known pollinators, were included in the study which focused on around 19,000 ‘cells’ each covering a square kilometre of countryside.