The availability of floral resources and habitat were two other significant factors the researchers measured that have an impact on wild bee populations.
A group of researchers from Concordia claim in a recent paper published in the journal PeerJ that the recent decade’s explosive growth in urban beekeeping may be having a detrimental effect on the local wild bee populations.
They speculate that small bees with constrained foraging areas may be particularly vulnerable. The researchers compared information on bee populations they gathered in 2013 from locations on Montreal’s island to information they gathered at the same locations in the summer of 2020.
According to the study’s lead author, Gail MacInnis, a former Concordia postdoctoral researcher, “we found that the sites with the largest increase in urban honeybee population across sites and years also had the fewest wild bee species.”
Co-authors include Carly Ziter, an assistant professor in the Department of Biology, and Etienne Normandin from the Université de Montréal.
The number of honeybee colonies on the island of Montreal has increased more than twelvefold, according to Quebec’s Ministère de l’Agriculture, des Pêcheries et de l’Alimentation (Ministry of Agriculture, Fisheries, and Food). There were fewer than 250 colonies in 2013. By 2020, that number will have increased to almost 3,000.
The researchers point out that honeybees are not native to the area. According to the 2013 study, this kind of bee is thus in competition with almost 180 other species for resources like pollen and nectar. 15 locations known to draw pollinators were visited by the researchers on Montreal’s island. Community gardens, cemeteries, and sizable urban parks were among the locations.
To gather their samples, the researchers followed a standardised procedure using pan trap triplets, colourful bowls made to draw bees. Between late June and early September 2020, each site was sampled five times, yielding a total of 6,200 bees.
The availability of floral resources and habitat were two other significant factors the researchers measured that have an impact on wild bee populations.
120 different species of wild bees were discovered in nearly 4,000 samples. There were roughly 2,200 urban honeybees. In contrast, similar locations saw the collection of 5,200 bees in 2013. These samples included almost entirely wild bees from 163 different species.
In 2020, statistical analyses on wild bee diversity, bee traits and honeybee abundance, wild bee community composition, and pollen depletion were carried out across sites. Analyses that compared the bee communities of 2013 and 2020 were similar. The study discovered a sharp decline in the diversity of wild bee species.
In areas where the honeybee population was relatively lower, honeybee abundance increased but stayed close to 2013 levels. Pollen depletion in white clover flowers was also correlated with honeybee abundance.
According to MacInnis, it is challenging to study bee populations because there is no registry or legislation. She claims that since a single honeybee colony can support up to 50,000 individuals, understanding honeybee colony density is essential.
“If we want to support large bee populations, we must provide food. But because commercially managed bees are more susceptible to disease, we also need to be cautious about population density,” “she claims.
“When there are numerous new beekeepers in the area, this problem may get particularly bad. They might not be as knowledgeable about preventing pathogens like viruses, mites, and other pests.”
“In the form of honey, beekeeping produces an agricultural product that is beneficial to people. Urban beekeeping is frequently misrepresented as a way to stop biodiversity loss, which worries me,” says Ziter.
“We shouldn’t look to beekeeping to save the bees, just as we wouldn’t advocate keeping backyard chickens to save the birds. It’s critical that our intentions and behaviours line up.” “Planting pollinator gardens is a much better option than adding more urban hives if our goal is to increase urban biodiversity.”