Bees are a wondrous gift of nature. Many of us have marveled as these fascinating creatures forage intently in our gardens. As they flit from flower to flower, filling the air with their soothingly monotonous drone, they take on an ever-larger cargo of pollen. Bumblebees, especially, with their oversized bodies and tiny wings, seem to defy all known laws of aerodynamics.
While the sad state of dwindling honeybee populations worldwide has now been well documented, much less attention has been paid to their ungainly cousins, the bumblebees. They too are declining at an alarming rate and have been for at least a decade. But only recently have details of their predicament begun to emerge.
Bumblebees - an overview
There are about 250 bumblebee species worldwide, and about 50 are found in North America. While honeybees are imported from elsewhere and are cared for by beekeepers, bumblebees are native to their home ranges and live in the wild. In some cases, bumblebees are even better pollinators than honeybees. They need less light and warmth to gather pollen and use a technique called buzz pollination which dislodges the pollen more efficiently. They grasp flower stems in their jaws while beating their wings, performing a unique dance. They are docile and sting only rarely and in self-defense.
The evidence of decline
In a 2007 report called “The Status of Pollinators in North America,” the prestigious National Academy of Sciences was among the agencies sounding the alarm. Though the report that didn’t get much media attention at the time, the academy stated that “long-term population trends for several wild bee species (notably bumblebees), are demonstrably downward.” The agency added that both local and global populations of bumblebees are declining, with some species being declared endangered, or worse, extinct.
Sheila Colla, a Ph.D candidate in biology at York University in Toronto, has done extensive field studies of bumblebees in both Canada and the U.S. From 2004 to 2006, Colla was part of a team searching for the species B. affinnis, once commonly found from southern Ontario and down into the U.S. To their dismay, Colla and her team found one bee. No, not one species. Not one sub-species, but just a single bee foraging on a sunflower in a provincial park in Ontario. In the U.S., things were worse – they didn’t find any.
British scientists have drawn similarly gloomy findings. Paul Williams of the Department of Entomology at London’s Natural History Museum and Juliet Osborne of the Department of Invertebrate Ecology at Rothamsted Research Station in Hertfordshire have found bumblebee species in decline in Europe, North America and Asia. In Eastern Europe and Russia the news is almost as bad as it can be. Williams and Osborne describe those areas as having “the largest concentration of species categorized as endangered, or worse.”
The non-profit Xerces Society has been working for more than 30 years to save bumblebees through habitat preservation in the U.S. About a decade ago, they noticed that three different bumblebee varieties (western, rusty-patched and yellow-banded) were dwindling in western Canada and the U.S. The rusty-patched variety was once commonly distributed throughout the east and upper U.S. midwest but has steeply declined in recent years.
And it’s feared that another variety called Franklin’s bumblebee may now actually be extinct after Robinn Thorp, a Xerces entomologist at the University of California, found only one of these worker bees near the Pacific Crest Trail in Oregon. That was three years ago. When Thorp first started tracking the pollinators during the 1960s, their numbers were “robust.”
From the field to your mouth
Bees are important contributors to life on earth. Honeybees pollinate up to one third of human food crops. But bumblebees, which account for another 15 per cent of bees, can’t be overlooked for the critical role they play either. Taken together these creatures are responsible for practically one out of every two spoonfuls of food we put in our mouths.
And bees are worth big money. French and German scientists place the worldwide economic value of insect pollination at U.S. $217 billion. The Canadian Pollinator Initiative (CANPOLIN) estimates that insects pollinate around $1 billion worth of agricultural crops each year in this country.
Based at the University of Guelph, CANPOLIN looks at all aspects of pollination, including the health and conservation of pollinators themselves. It notes: “This decline poses a serious threat to natural ecosystems and crop production.”
Sheila Colla describes bumblebees as key to the production of tomatoes, cucumbers and sweet peppers. Meanwhile, Xerces notes that rusty-patched bees in particular are also an excellent pollinator of wildflowers, cranberries, plums, apples, alfalfa and onions. It should also be noted that countless wildflowers (important food for both bees and other wildlife) will vanish if bees do, raising the bar from serious to potentially catastrophic.
It seems like everything we do…
So, just what is behind this disturbing decline? Well, us. You and me. Williams and Osborne note that “land use changes” have disrupted bees’ natural habitats. That, of course, means human development: logging, urban sprawl, livestock overgrazing and pollution. All of these destroy plants which are bees’ food source.
But that’s not all. Pathogens are hitting some species especially hard. According to Xerces, “the dramatic decline in wild populations of these species coincided with a disease outbreak in populations of commercially-raised bumble bees distributed for greenhouse pollination in western North America.” Given this timing, the Society believes that an exotic disease organism that escaped from these greenhouses may be the cause of this widespread loss.
And as in numerous other studies on declining bee populations, agricultural pesticides are implicated. Williams and Osborne state that while it’s still unclear, “pesticides could affect bumblebee populations either directly as insecticides that kill bumblebees or indirectly as herbicides that kill their food plants.” It is likely that incidents of honeybee poisoning from insecticides will also have affected wild bees (studies suggest pesticide toxicity is similar for bumblebees and honeybees). The use of herbicides to kill flowering plants in intensively managed grassland and crops may be an important driver of bumblebee declines on a global scale.
CANPOLIN lists other causes, too, including “malnutrition and climate change.”
Is our food supply being affected yet?
About eight years ago, researchers were noticing that dwindling numbers of insects such as bees, were harming food production. In 2001, Peter G. Kevan of the Department of Environmental Biology at the University of Guelph helped prepare a report entitled, “The Economic Impacts of Pollinator Declines.” It stated, “We conclude that there is ample information to suggest the existence of pollinator declines that have affected, and are affecting, agricultural productivity. Adverse economic effects of pollinator deficits on food prices have extensive ramifications for world food supply, security, and trade.”
And Xerces refers to evidence that some insect-pollinated plants in England and the Netherlands, where multiple bumblebee (and other bee) species have gone extinct, are declining. The National Academy of Science says rare plant species could become increasingly vulnerable. In Manitoba, there are anecdotal reports of a decline in some vegetable crops such as pumpkins, although there has been no analysis into the cause.
What’s to come?
The Soil Association of Scotland believes it might be able to help. The Association, which promotes organic farming says “the lack of pesticides in organic production, provides a haven for the bee. Wild spaces at field margins and in hedgerows, provide a diversity of flowers and habitats for bees to nest and shelter. Organic farming supports both bio-diversity and the bee.”
There’s no evidence that our relentless assault on the planet will let up any time soon. Nor is there a lot of hope that the fate of other pollinators will prove any different. According to CANPOLIN, 28 species of butterflies and moths are also known to be at risk in Canada. One thing is certain, the final chapter in this story is far from written yet.
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