Fight of the Bumblebee

The honeybee hives at the University of Guelph, in south-central Ontario, used to sit in the middle of the campus, surrounded by tall hedges that forced the drones to fly up and out of harm’s way. “Back then, nobody fussed about bees,” says Paul Kelly, the fifty-four-year-old apiarist who oversees the 300 or so hives the university maintains on and off campus. Today, the main apiary is down the road, where it has been managed out of an unassuming brick bungalow since the 1960s. In the bee yards at the front and back, the multicoloured hives are stacked higgledy-piggledy but with purpose: if Kelly lined them up in rows, it would confuse the foragers, who might then return to the wrong hive. “They can’t count,” he explains, his blue eyes twinkling. His brisk pace slows down considerably as he nears the yard.

A beekeeper’s main task, he says, is to prevent swarming. If a queen decides to abandon the hive, half of the colony will follow her, leaving the other half behind to repopulate it; until they do, the hive is far less productive. “You’ve gotta be tuned in to where they’re at,” he explains, carefully laying his hand on top of the bees as they crawl across a frame he has pulled out to inspect. He has me do the same. They feel surprisingly warm and furry under my palm, and the experience is strangely calming, not unlike patting a dog or a cat. “You have to watch what’s going on,” he says. And you need to keep the bees happy: if they feel cramped or uncomfortable, or if the queen is getting on in years, they are more likely to swarm.

Another task, which grows in importance with each passing year, and which, arguably, should be the apiarist’s first concern, is keeping at bay the twenty-nine documented pathogens that plague honeybees. Guelph operates one of the largest honeybee research programs in Canada, under the direction of Ernesto Guzman, a professor of apiculture at the School of Environmental Sciences. In Guelph’s laboratories, experts study the genetics and behaviour of Kelly’s bees, trying to understand the causes of honeybee mortality, and to breed species that can resist the stress of parasites. “The mites are terrible this year,” says Kelly, pointing to a rusty brown mite that has attached itself to the back of one of the hundreds of bees on the frame. A few cells over, a newborn emerges, dewy eyed and fluffy. “I’m worried that we’ll lose a lot of colonies this winter,” he adds.

Mites have plagued Canada’s honeybees since the late 1980s. The 1970s had been good years for beekeepers. World honey prices had increased from fifteen to fifty cents a pound, and as the business became more lucrative the number of beehives in Canada rose dramatically. At the time, hives could be imported from the US, allowing beekeepers to build up colonies quickly. Then, in 1987, the border was closed, in an effort to keep out tracheal and varroa mites, which had already been found in American hives. But even that couldn’t stop the pests. No one knows for sure how infected bees reached New Brunswick in 1989. They may have made their own way here, or, as Guzman suggests, a beekeeper could have smuggled them in; a queen in a small plastic test tube is easy enough to carry across the border undetected.

Guzman, who grew up in a small town in Oaxaca, Mexico, and used to keep bees on his apartment roof in Mexico City, believes Varroa destructor is the leading cause of honeybee mortality in Canada. He has produced a study of 400 hives to support this hypothesis, though he allows that other factors may weaken the bees’ immune systems and make them more susceptible to mites and the viruses they carry.

At first, beekeepers managed to control infestations with synthetic miticides, but over time the parasites developed a resistance to them. As an alternative, Kelly employs less aggressive, more organic treatments, such as thymol, derived from an essential oil of thyme. However, controlling pathogens continues to prove challenging. “You’re trying to kill one bug that lives on another bug that lives in a box of food,” is how Kelly puts it. Guzman, whose lab can decode a bee’s 237 in a matter of hours, suggests that one solution is to develop more resistant bees. So Guelph keeps hives on Georgina and Thorah Islands on Lake Simcoe, where bees can be bred in isolation to reduce the chances of accidental mating with wild or competing honeybee colonies. (In one way, the closed border has been a boon: Canadian apiarists have succeeded in breeding kinder, gentler races that are easier to work with.)

In the years following the varroa mite’s arrival, Canadian beekeepers had to adjust to higher mortality rates. Soon 15 percent was routine. Then, between 2006 and 2012, that doubled: four out of the past six years have seen winter losses just above or below 30 percent. While apiarists here are not experiencing colony collapse disorder — which is characterized by bees abandoning their hives rather than dying in them — they sometimes face mortality rates comparable with those in the US.

Most researchers agree on the first ten causes of bee mortality, if not how to rank them. Guzman’s lab focuses on five: varroa mites, tracheal mites, the nosema virus, overwintering, and colony population. Of these, he says varroa can be linked to 85 percent of mortalities. The nosema virus is a contributing factor but does not kill a hive’s inhabitants. Everything else, he says, points to poor management practices. “Beekeepers blame everything but themselves,” he says with some exasperation. Even mites have a lesser impact under good stewardship.

Perhaps the bees are dying because the methods we use to produce our food are unsustainable. Beekeepers have become more aggressive about removing honey and pollen and prematurely dividing colonies — practices that can compromise a hive’s well-being. More bees are being trucked over longer distances to perform pollination services, preferably at night, because they can overheat and die during the day. Synthetic brood pheromones are sometimes used to increase production by tricking the bees to do more foraging, and, increasingly, bees are being forced to feed on monocultural diets from single crops. “The economic reality is that beekeepers have to manage intensively,” says Kelly — perhaps not always in the best interests of the bees and the many species, us included, that depend on them.

In the late 1960s, Peter Kevan, the grandfather of pollinator science in Canada, watched a well- meaning government phase out the toxic pesticide DDT in New Brunswick. Instead, forestry crews were given a biodegradable organophosphate, fenitrothion, to control spruce budworm, spraying it across huge swaths of coniferous forest. It seemed like a good idea at the time, but it turned out that fenitrothion (which is closely related to the nerve gases used in World War I) was even more toxic for the wild bees and bumble- bees on which the province’s blueberry crops depended, and crop yields collapsed. The timing of the spraying, at the height of blueberry flowering, was especially unfortunate. The use of fenitrothion was later abandoned, although it took up to eight years for some native bee populations to recover, and berry yields continued to drop until growers brought in honeybees to make up the pollination deficit.

In 2012, Kevan wondered if history was about to repeat itself. Within the environmental sciences, one of the more controversial families of pesticides is the neonicotinoids, which are similar in chemical structure to nicotine and used to coat corn seeds. They have been applied to crops in North America since the early 1990s, even though the US Environmental Protection Agency has shown them to be highly toxic to bees. Last spring was unseasonably dry in Ontario, and during planting the wind blew clouds of neonicotinoid-treated seed coatings over southern Ontario cornfields. Bees — both managed honeybees and wild species — began dying, and in June a delegation of Ontario beekeepers went to Ottawa to lobby for a ban. While this was the first neonicotinoid-related calamity in Canada, similar cases have been documented in Germany, Italy, and the US.

Even if neonicotinoids are as dangerous to bees as Kevan believes, pesticides contribute to a larger problem: habitat degradation. While the initial clearing of forests probably benefitted many species, the juggernaut of sprawl and intensive farming have made life ever more difficult for most of them. As new technologies come to market, farmers are finding ways to make every bit of land yield more crops — and to eradicate the flower- ing weeds that may compete with them but might also sustain native bees. Habitat loss is one of the reasons we have become so dependent on the mobile pollination services of honeybees. The rule of thumb is that the more a habitat is managed or devoted to one crop, the less diverse the surrounding bee populations. Down east, for example, scientists have observed that wild bees can only pollinate blueberries if the fields are small. In fields of more than a few hundred square metres, bumblebees and other wild pollinators will not penetrate deeply into the monoculture. It is too far to fly for an efficient forager. Wild pollinators that do establish nests in the middle of large fields fare poorly; while they can gorge on nectar during blooming, they starve once the blossoms die off. Honeybees do much better in these circumstances, flying up to three kilometres to forage, and relying on beekeepers to move them to new feeding grounds.

“In the past, when people had small mixed-use farms, wild bees did well and could provide adequate pollination,” says Cory Sheffield, an alumnus of Laurence Packer’s lab at York University who now works at the Royal Saskatchewan Museum. He visited the Annapolis Valley in Nova Scotia to compare bee diversity in apple orchards in highly managed monocultures with those in natural and semi-natural habitats, and for a baseline he also collected bee samples in a wild setting. He found that farmers could more than double their crops if they left small strips of flowers for the bees to forage in after the apple blossoms had disappeared. Other conservation biologists have demonstrated similar results. The irony is hard to ignore: agriculture, the very industry that depends most on pollination, might be the prime suspect in the demise of our pollinators.

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