For over a decade, bee populations have been declining dramatically all over the world. There are likely a number of compounding causes, including pesticide use, viruses and global warming. But another major factor is a loss of habitat and a decline in wildflowers, particularly species preferred by bees.
Wilderness often loses ground to agricultural uses, but a new study from the University of Essex shows that farms can boost wild bee populations by saving room for flowers. The paper was published this week in the scientific journal “Molecular Ecology.”
In 2005, England introduced incentives to farmers to plant more bee-friendly flowers on their land. Similar incentives also exist in the E.U. These agri-environmental schemes have been shown to attract bees a provide them with a good source of food, but the new paper shows for the first time that they are also associated with increased populations.
“A consistent problem in assessing the response of bumblebees to agri-environment schemes has been that it is unclear whether a high observed abundance of bumblebees was merely an attraction of workers to sown forage patches or a genuine population level increase,” write the authors. So, they set out to determine the number of wild bee colonies on the different types of farms, which they say is a good measure of the overall population of bees.
Using this measure, the researchers compared nine farms that have areas planted with flowers for bees with nine farms that don’t have special pollinator-targeted planting over the course of two years. In addition to observing and counting the bees, the researchers collected non-lethal DNA samples to determine how many bee colonies visited the different types of farms.
The researchers found that the colony density of the four most common types of bees was significantly higher at farms with flower-rich patches. They also observed a greater number of individual bees. That’s good news for the crops and wild plants that rely on bees for pollination. It’s also good for the people that eat those crops and enjoy those wildflowers.
However, the researchers did not find that the farm intervention is significantly helping the rarer species of bees that may need support the most, like the large garden bumblebee (Bombus ruderatus). One possible explanation is that these species may have smaller foraging ranges, and the farms with flower patches may be too few and far between to benefit them. It’s possible the rarer bees may need more targeted planting if our goal is to prevent them from disappearing. Since the 1940s, two species of bumblebees have gone extinct in the UK.
Nonetheless, it’s encouraging to see that with the right policy incentives, farms can be a part of the solution to the global bee decline.