Urban beekeeping can’t save the bees, new research finds: Why backyard beekeepers should take note

Toronto`s official bee, the metallic green sweat bee — Agapostemon virescens — is one of the bees that could be threatened by the influx of honeybees in urban settings. (City of Toronto)

To bee or not to bee — that is the question that many urban beekeepers are asking themselves in the wake of new research suggesting their hives might be hurting wild bee diversity.

Jode Roberts first got into beekeeping around two decades ago, and has been operating honeybee hives on his rooftop in Toronto for the last few years.

But this spring, he won’t be beekeeping.

“I’m giving up the hives on my roof,” he told CTVNews.ca in a phone interview. “Beekeeping is not bad, but it has been shown to be bad for bees at the levels that are found in Montreal and lots of urban neighbourhoods.

“Right now we need to take stock, see where the hives are, and manage beekeeping in a way that isn't negatively affecting wild bees.”

His decision is in part because of a new study by researchers at Concordia University who found that as honeybee hives run by urban beekeepers exploded in popularity, the number of different wild bee species in the Montreal area fell over the same time period.

In the study, published earlier this year in the peer-reviewed journal PeerJ Life and Environment, researchers outline how the number of honey hives in the Montreal area skyrocketed from fewer than 250 in 2013 to nearly 3,000 in 2020.

That’s a 1,200 per cent increase over less than a decade.

Researchers believe the increasing number of hives connected to urban beekeeping is leading to some wild bees being choked out of their territories due to over competition for flowers and plants, as well as increased pathogen transmission.

“When I started beekeeping 20 years ago, it was not a popular thing,” Roberts, who is also the manager of the David Suzuki Foundation’s Rewilding Communities program, said. “It was a curiosity to bring up at dinner parties. Whereas in the last decade, particularly, there's been this dramatic increase in interest in keeping honeybees. And now we're getting to the point where we can now document the impact on the rest of the wild bees.”

Researchers collected data at 15 sites across the island of Montreal, including urban green spaces known to attract pollinators, such as community gardens, cemeteries and two large nature parks. They measured the number of bees by trapping some and noting down others visually, and assessed how many pollinators the different plants in each region would be able to serve before other pollinators would have to search elsewhere.

They found 3,926 wild bees belonging to 120 species — a decrease in wild bee diversity compared to the 163 wild bee species found in Montreal in 2013.

“We found that the sites with the largest increase in honeybee populations across sites and years also had the fewest wild bee species,” Gail MacInnis, a former Concordia postdoctoral researcher and the study’s lead author, said in an April press release.

Even one extra honeybee hive introduces thousands of bees to an environment.

“One honeybee hive, over the course of the summer, can have up to 40 or 50,000 honeybees in it,” Roberts said. “The best analogy I have is when a honeybee hive goes in your neighbour's backyard or on a rooftop nearby, it's like a Skydome filled with honeybees. And now we know they are directly competing (with) and outcompeting a lot of wild bees.”

IS IT SAVE THE BEES, OR SAVE THIS ONE BEE?

It’s a common conservation cry: save the bees. But this movement has been almost wholly focused on one type of bee, the same kind which is the centre of the urban beekeeping movement.

Urban beekeepers construct and maintain the health of bee hives within an urban setting, with the vast majority of beekeepers operating hives for the European honeybee, also known as the western honeybee.

Its scientific name is Apis mellifera L., and it’s by far the most common species of honeybee worldwide, responsible for the sweet treat we can buy at farmer’s markets and grocery stores. While their native range is limited to Europe, western Asia and Africa, human activity has brought the western honeybee to all corners of the globe.

In the process, the bees native to Canada may be getting a less than sweet deal out of it, research suggests.

“The honeybees have received a lot of attention,” Roberts said, adding that part of this is because human beekeepers are more likely to notice declines in honeybee populations and raise alarm bells. “There's this vast ecosystem of wild bees that people don't really know exist.”

For instance, Toronto actually has an official bee — but because it has a bright green head and body, most people wouldn’t recognize it as a bee at first sight.

Many of the wild bee species are much smaller than the western honeybee, and have smaller foraging areas, making it harder for them to rebound if their territory is lost to a larger bee.

“If you plant a couple skydomes full of bees within the range of those tiny little wild bees, there's going to be long lineups at the floral buffet for those wild bees,” Roberts said, adding that while honeybees have human caretakers to provide a new queen if the colony is dying out, wild bees don’t have the same option.

While it’s difficult to pinpoint the exact ripple effect of one species of bee dying out, Roberts said, there are certain plants that need specific pollinators.

“We don't know exactly what's going to happen if you remove one or 100 species of bee from an urban area,” he said, noting that he isn’t a scientist. “But we do know there's some bee and plant-specific relationships that are important that honeybees can't be a replacement for.”

For instance, the right type of bee to pollinate tomatoes is a bumblebee, due to its ability to physically buzz hard enough to dislodge pollen — something the honeybee can’t do.

“When you remove one piece of the web or the puzzle, then there's unintended consequences,” Roberts said.

In the Montreal area alone, there have been more than 150 species of wild bees serving as pollinators for thousands of years to help keep local plants flourishing.

The majority of the decline in wild bee diversity is caused by larger factors, researchers acknowledged, such as pesticide use and human land development like expanding urbanization. But within cities, there are areas where wild bees thrive due to pesticide-free bylaws and deliberate biodiversity projects in urban gardens, and the biggest threat those bees currently face appears to be the human desire to make honey in our backyards.

SHOULD WE SAY ‘BUZZ OFF’ TO BEEKEEPING?

Researchers stressed that urban beekeeping itself isn’t all negative, and that it’s about balancing hive numbers to keep things sustainable.

They recommend a precautionary density of around three hives per square kilometre in urban centres, which would mean that Montreal’s hive density is currently twice as high as it should be.

“Beekeeping provides an agricultural product that is valuable to people in the form of honey. My concern is that urban beekeeping is often falsely marketed as a solution to biodiversity loss,” Carly Ziter, assistant professor in the Department of Biology at Concordia and co-author of the study, said in the release. “Just as we wouldn’t advocate keeping backyard chickens to save the birds, we shouldn’t look to beekeeping to save the bees. It’s important that our actions match our goals or motivations.”

Roberts may be giving up beekeeping in the hopes of encouraging other urban beekeepers to think carefully about the threat to wild bees, but he understands that it’s “fun and awesome,” adding that keeping bees has brought a lot to his life.

“Honeybees are awesome little critters and do amazing things, it's just mind boggling,” he said, adding that he’s seen more and more neighbours take up beekeeping, often with the well-intentioned goal of helping bee populations.

“We just need to take a step back at this point, not vilify urban beekeepers, but we definitely don't need more urban beekeepers.”

HOW TO ENCOURAGE WILD BEE POPULATIONS

If you want to help wild bees flourish, one big step is to say goodbye to the manicured lawn — or at least carve out a space where natural wildflowers grow and the lawn mower isn’t constantly chugging through.

Most wild bee species nest in the ground or within cavities such as stems, tree trunks or rotting wood.

“It's easy to be a wild beekeeper if you just leave more nature in its place in your yard or neighbourhood,” Roberts said.

“We can all be wild beekeepers, we just keep more native wildflowers and shrubs and trees things flowering through throughout the seasons.”