Urgent action is needed to stop the decline of wild bees, and B.C. cities and their residents could pitch in by protecting and planting more bee-friendly flowers.
That’s one of the recommendations of SFU biologists Elizabeth Elle and Julie Wray in a report to Metro Vancouver that outlines the threats to bees.
“The main reason that wild pollinators are declining is loss of habitat,” Elle said in a recent presentation to Metro directors. “They’re losing their food and they’re losing their nests.”
Bees need nectar-producing flowers and while commercial blueberry fields are one source, it’s a monoculture crop that blooms for only a few weeks, leaving vast areas devoid of food the rest of the time.
Wild bees aren’t transported from field to field in boxes like imported pollinator honeybees and they require flowers that bloom at various times all year long.
More of that kind of habitat could be created by cities in parks and even by households and businesses in yards and other urban areas, Elle said.
She noted Metro Vancouver has already been planting diverse wildflowers and other native plants that bloom throughout the year in some regional parks.
Researchers have measured a 25 per cent increase in both the abundance and diversity of pollinators at those sites, she said.
Wild species nest in the ground, in trees or other areas and that habitat is also being lost to urban development or other ecosystem disruption.
Read the full report below and see pages 12-13 for a list of bee-friendly plants
Elle noted invasive species are a particular problem.
The Himalayan blackberry, she noted, can cover large areas where other flowers are effectively forced out and no nectar is available for most of the year.
Solitary bees only survive four to six weeks, so that species won’t survive in an area if food isn’t available when they come out.
Much public attention has focused on the threat to bees from farm pesticides, including neonicotinoids – there have been repeated calls to ban the neuro-toxic insecticides that have been found to kill beneficial insects.
Elle said the chemicals are linked to colony decline and even when they don’t kill bees outright they can hurt their ability to survive and thrive.
“Just smelling a fungicide reduces the ability of a bumble bee to find food and to collect it quickly and bring it back home,” she said. “What this means is they’re not provisioning a colony very quickly and the colony is not growing – just by smelling agro-chemicals.”
Some municipalities still allow cosmetic pesticide use, she noted, but said most exposure comes from farms.
Exposure to one pesticide can worsen the effects of another one on bees, she added, while imported European honeybees used to pollinate crops can be a source of diseases that spread to wild species and the managed bees also crowd out wild species.
Leafcutter bees are one of the many wild species found in B.C. that nest in areas like tree cavities.
She pointed to climate change as another source of trouble.
In high alpine areas, she said, wild flowers like the glacier lily are flowering earlier than they used to because the snowpack melts faster.
“Their main pollinator is a type of bumble bee that just isn’t active yet when the plants are blooming,” she said, adding that has limited the reproduction of the lillies, which no longer grow to the same extent.
The bottom line, Elle said, is bees are under pressure on multiple fronts.
“People want to know ‘What’s the one thing we can do?’ But it’s not a simple problem. It’s not just one thing that we can fix.”
However, Elle said even reducing one threat is likely to help bees and slow the declines.
More than 100 of the 450 bee species identified in B.C. live in the Lower Mainland but Elle believes many of them could go extinct and some may already be gone.
The local poster child for bee decline is the Western bumble bee.
They used to be commonly seen on blueberry farms in the 1980s but became very scarce about 10 years ago, Elle said. They haven’t been spotted on a farm in four years.
Metro Vancouver is expected to update its Ecological Health Action Plan this year with additional recommendations on conserving pollinators.