It may be easy to dismiss insects as pesky little buggers, but pollinators are vital to a healthy ecosystem and for global food security. Now, a third of wild bees and hoverfly species in Great Britain are in decline, with a quarter of regions losing wild pollinators once found there in 1980. 

In net terms, each square kilometer in the UK lost an average of 11 wild bee and hoverfly species, with only one in 10 species increasing in range during the 33 years of study. The research is published in the journal Nature Communications.

"Wildflowers and pollinators rely on each other for survival. Losses in either are a major cause for concern when we consider the health and beauty of our natural environment,” said Dr Gary Powney, from the Centre for Ecology & Hydrology, in a statement. 

Insect pollinators contribute to 75 percent of crop species and 35 percent of global crop production, according to the authors. However, threats to their survival come in many forms, including habitat loss, pesticide use, climate change, and increases in alien species. 

The study measured 353 wild bee and hoverfly species across Great Britain from 1980 to 2013. Bee species that pollinate oilseed rape expanded in range, likely due to farmers increasing the wildflowers they feed on with the help of government-subsidized schemes.

"While the increase in key crop pollinators is good news, they are still a relatively small group of species,” said Dr Powney. “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.”

"Non-crop pollinators are also vital for a healthy countryside rich in biodiversity; not only because of their crucial role in pollinating wildflowers, but as a key food resource for other wildlife,” he added.

Those that have declined in range include the red-shanked carder bee and the large shaggy bee by 42 percent and 53 percent, respectively. The lobe-spurred furrow bee and the ashy mining bee have both increased their range by fivefold.

More than 715,000 records were collected from the Bees, Wasps and Ants Recording Society (BWARS) and the UK Hoverfly Recording Scheme for the study.

"All important studies of animal population trends, such as this latest research, rely entirely on the wildlife recorders who go out and record sightings of different species in their area,” said Mike Edwards of BWARS. “Therefore, we would encourage more people to take part in wildlife recording, so we can increase our understanding of how wildlife is responding to environmental change.”

Co-author Dr Claire Carvell added: "While this analysis sends us a warning, the findings support previous studies suggesting that conservation actions, such as wildlife-friendly farming and gardening, can have a lasting, positive impact on wild pollinators in rural and urban landscapes. However, these need further refining to benefit a wider range of species."