Bumblebees living in urban areas outbreed those in the countryside, a new study has revealed. Colonies in agricultural areas produced significantly fewer reproductive offspring.
City-dwelling bumblebees fare better than their countryside cousins, with the important pollinators facing multiple threats such as land-use change and pressure from parasites and disease.
The findings come despite the fact that urban regions are usually considered to be less wildlife friendly.
“We wanted to understand if this was a case of bees simply moving into urban areas or whether urban bee colonies are more successful, and able to produce more offspring,” explained lead researcher Ash Samuelson, a PhD student from Royal Holloway, in a statement.
To examine the phenomenon, the researchers reared colonies of wild bumblebees and placed them into 38 gardens and farms in areas including inner city London and farmland in Berkshire. The bees were then monitored for ten weeks.
The researchers found that the bumblebee colonies placed in agricultural areas produced significantly fewer reproductive offspring than those in village or city sites, meaning they would be less able to pass their genes on to the next generation.
Ash explained: “Although it seems counterintuitive that the ‘unnatural’ environment of a city is beneficial to bees, we have to remember that modern agricultural areas are also very far from the habitats in which these bees evolved.
“The fact that bees performed poorly in farmland reflects the increasingly apparent realisation that intensive agriculture has negative impacts for wildlife.”
The abundance of flowers throughout most of the year in gardens and parks may help explain why the bees thrive, while the loss of wildflowers in agricultural areas may mean bees have fewer resources. Furthermore, the use of pesticides in agricultural land could have a negative impact on the health of colonies.
“Our results suggest that bees are able to use cities as a refuge within the barren agricultural landscape, and policy-makers should focus on improving farmland for bees by supplementing floral resources and managing pesticide use,” Ash concluded.
Photo credit: Jeffery DelViscio/ CC BY-ND 2.0