Widespread British pollinator losses

Bee on a flower

Many pollinating insects are on the decline but the ashy mining bee has thrived in recent years

27 March 2019 by Simon Williams

Insects that play an important role in pollination are disappearing from areas of Great Britain.

Research, led by the Centre for Ecology & Hydrology (CEH), measured the presence of 353 wild bee and hoverfly species across the country. They found that from 1980 to 2013 one third of species experienced declines in terms of areas in which they were found, while one tenth increased. On average, the geographic range of bee and hoverfly species declined by a quarter. This is equivalent to a loss of 11 species from each square kilometre.

A positive but unexpected finding was the increase in bee species responsible for pollinating flowering crops, such as oilseed rape. This could be in response to the increase of mass-flowering crops grown during the study period and government-subsidised schemes that encourage farmers to plant more of the wildflowers they feed on.

Overall losses were more notable for pollinator species found in northern Britain. Climate change may be to blame, with species that prefer cooler temperatures reducing their geographical spread in response to less climatically suitable landscapes.

Dr Gary Powney from CEH, who led the research, said:

We used cutting-edge statistical methods to analyse a vast number of species observations, revealing widespread differences in distribution change across pollinating insects. There is no one single cause for these differences, but habitat loss is a likely key driver of the declines.

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. 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.

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. 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.

Dr Claire Carvell at CEH, a co-author of the study, points out there are multiple environmental pressures leading to changing patterns of occurrence in bees and hoverflies. She said:

There is an urgent need for more robust data on the patterns and causes of pollinator declines. 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.

In addition to recording species sightings, more standardised monitoring of pollinator numbers is required at a national level and a new UK Pollinator Monitoring Scheme has been set up to do just this.

Over 700,000 records were analysed for this study. Most were collected as part of the Bees, Wasps & Ants Recording Society (BWARS) and the UK Hoverfly Recording Scheme, in more than 19,000 1km by 1km squares across Great Britain. It's thought to be the first study of its kind, since there have been no previous large-scale, long-term, species-specific estimates of distribution change for pollinating insects in Britain.

Mike Edwards of BWARS said:

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. 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.

Members of the public can find out more about getting involved in recording insect pollinators on the UK Pollinator Monitoring Scheme website - external link.

Here are some examples of bee species who have either declined or survived over the years:

Losers:

  • Red-shanked carder bee - declined by 42%. Formerly a widespread bumblebee species found in much of England and Wales, and part of Scotland.
  • Smooth-gastered furrow bee - declined by 40%. Widely found in southern Britain, where it tends to be found visiting blackthorn flowers in the spring.
  • Large shaggy bee - declined by 54%. Found in coastal regions in Southern England and Wales, where it can be found nesting along the edges of footpaths.

Winners:

  • Ashy mining bee - fivefold increase. Currently a widespread species found in large parts of England and Wales. An important crop pollinator, particularly for oilseed rape.
  • Ivy bee - 16% increase per year since arrival in 2001. Colonised mainland Britain in 2001, where it was recorded in Dorset. Since then it has been spreading rapidly.
  • Lobe-spurred furrow bee - fivefold increase. Formerly a rare species, and now considered an important crop pollinator in England.

The Centre for Ecology & Hydrology (CEH) receives funding from NERC and is a world-class research organisation focusing on land and freshwater ecosystems and their interaction with the atmosphere.

'Widespread losses of pollinating insects in Britain' - Gary D Powney, Claire Carvell, Mike Edwards, Roger KA Morris, Helen E Roy, Ben A Woodcock, Nick JB Isaac, 2019, Nature Communications.