Wild bees can boost your crop yields
There’s an estimated 300 species of wild bees in Alberta, and they can’t be beat as pollinators
Wild bees buzzing around your field can give you a bigger bang for your buck than honeybees or leafcutter bees.
That’s because they actually do a better job of pollinating, said #bee specialist Ralph Cartar.
“Our whole world is built around managed bees and using honeybees as best we can, but in fact, the most reliable thing is native bees — they have a huge impact on yield,” the University of Calgary biology professor told FarmTech attendees
“Leafcutters are great individual pollinators. Honeybees are not as good, but you can make up for it by having more (of them). Collectively, neither is as good as wild bees.”
Honeybees are not great movers of pollen because they are not very hairy and so not as much pollen sticks to them. But the challenge with wild bees is getting the high density that you can get by putting out a group of hives.
Still, the wild guys are so effective at gathering pollen, they can have a big effect on yield. Studies done on canola in Sweden found yield increases of up to 18 per cent when wild pollinators were around.
And the wild freelancers are needed more than ever, said Cartar.
“Worldwide, there are more crops being grown that require pollination, and the ones that require insect pollination are increasing at a higher rate.”
However, the population of honeybees isn’t increasing as fast. So on a global basis, honeybees are doing 20 per cent of crop pollination and wild bees the remainder.
The buzz in Alberta
So what’s the story here?
There are 300 bee species native to Alberta, but little is known about them. A specialist in bumblebees, Cartar gave a rundown on some of the main types, including plasterer bees (small insects that produce and secrete a substance that smooths walls of cells in a nest), sweat bees (a diverse group that actually feed on the salt and liquids in sweat), mining bees (which make holes in the ground to nest), and long-tongued bees (adept at sucking nectar from deep flowers). There are also mason bees, that like leafcutters, nest in tubes, straws or holes.
Unfortunately, no one in Alberta is monitoring what is happening with wild bee species.
“No one knows if the populations are increasing or decreasing. We barely know what’s there,” said Cartar. “But people who do know what is there can tell you that we live in the centre of a diversity of bees.”
In fact, the Prairies rank with the Okanagan and southern Ontario in having the greatest density of wild bees.
The British and the Dutch do monitor wild bee populations and both countries have seen declining numbers, likely due to habitat loss. The same is true for North America bumblebees, although there’s no specific data for Canada.
However, that doesn’t mean that the situation is universally bad.
“Since I came here almost 25 years ago, we’ve lost one or two species that used to be really common,” said Cartar, originally from Vancouver.
“But it doesn’t mean that there aren’t a lot of bumblebees on the flowers. They are just different species. It’s bad to lose species and to lose that diversity, but it doesn’t mean that bumblebees as a whole are going extinct.”
Studies in Europe have shown livestock density, pesticide use, and loss of habitat can affect the diversity and abundance of wild bees, as can the introduction of alien species like bumblebees or honeybees. But pathogens are a likely culprit, and climate change is also having an impact. One of Cartar’s colleagues found the range of bumblebees is shifting due to changes in temperature.
“The range of the south is shifting up as the range of the north stays the same,” said Cartar. “The regions are squishing. The south is being lost, but the north is not being gained.”
Helping wild bees
Leaving natural habitat around fields boosts wild bee numbers.
Studies done in Lethbridge found populations increase when there’s more flowers and nesting sites, and a strong positive correlation between native pasture land and wild bee numbers.
Cartar recommends keeping an eye out for wild bees and then determining where they’re nesting.
“If you are trying to explain the abundance of critters in your field, look around 300 metres,” he said. “If you are looking at diversity, you need to look at 750 metres. Don’t look three kilometres away. Look at what’s in your field and what’s next to your field.
The edges of roads and lanes make for good habitat, along with fence boundaries, shelterbelts, and pivot corners (the corners of fields that pivot irrigation doesn’t reach).
“These are all important for pollinators, so look at these places and try to encourage that,” said Cartar.
Two free publications — Farming for Bees and Native Pollinators and Agriculture in Canada are available from a number of websites and can be found by Googling their titles.