Bumblebees living in the city have healthier colonies than their rural counterparts, according to researchers at Royal Holloway, University of London. Compared to agricultural colonies, urban bees hosted fewer parasites, produced more offspring, built up bigger food stores, and lived longer. The findings were published today (June 27) in Proceedings of the Royal Society B.
“There are a few species that are really able to exploit the urban environment—pigeons, rats, foxes,” study coauthor Ash Samuelson tells New Scientist. “It seems like bees belong to that group.”
To make the comparison, Samuelson and her colleagues went out into Windsor Great Park, a more than 4,000-hectare park in Surrey in the U.K., and captured nearly 200 wild bumblebee (Bombus terrestris) queens. From these, the researchers successfully raised more than 40 colonies, each with a single queen. ...
Next, they placed one colony at each of 38 sites spread across a variety of urban and rural environments in or near London. Visiting the sites once a week over the following months, the team observed that the colonies living in cities and villages scored substantially higher on multiple markers of colony success.
The team suspects the difference might partly be caused by a reduction in the number of parasite bees invading urban nests—brood parasite B. vestalis, for instance, might be thrown off the scent of bumblebee colonies by air pollution, the researchers suggest in their paper. Other possible factors include a greater number and variety of pollinator-friendly flowers in the city and a relative absence of harmful chemical pesticides.
The University of Plymouth’s Mick Hanley, who was not involved in the work, agrees that there are likely several contributing factors. “We have always suspected that many pollinators, not just bees, are doing better in urban environments,” he tells The Guardian. “But this actually gets at the nub, for one species, as to how and why they might be performing better biologically.”