Study finds wild bees boost crop yields

Wild bees and other pollinating insects can make quite a difference when it comes to crop yields, according to a new study.

“Our message is not that honeybees are bad — it’s that we could do better if, in addition, we were encouraging more activity by wild insects,” said Lawrence Harder, a professor of biological sciences at the University of Calgary.

Harder is one of 50 authors of a paper published this month in the journal Science, which looked at 41 different crops in 19 different countries, including low-bush blueberries in P.E.I.

Crops that are animal pollinated — such as cucumbers, tomatoes, blueberries, and coffee — get better yields when more than just honeybees are pollinating the flowers, Harder said.

“The point here is not that honeybees aren’t doing a good job, it’s more that basically in most of these fields they’re already maxed out in terms of the service honeybees are providing,” he said.

The pollination technique of wild bees also appears to make a difference. Honeybees usually move from flower to flower on the same bush, whereas wild bees move between bushes, which means more plants are pollinated with pollen from their neighbours. The study also looked at the impact of other wild insects, such as butterflies and some types of flies and beetles, but found wild bees have the biggest impact on yields.

If you want to encourage wild bees, Harder recommends growing natural or semi-natural vegetation with wild flowers along roadsides so they have something to eat when crops aren’t in flower.

“Canola’s a cornucopia when it’s in flower for bees, but when it’s not in flower it’s a wasteland,” he noted.

Other measures include not disturbing nests with tillage and using fewer pesticides that kill wild bees.

Honeybees are crucial for pollinating hybrid canola being produced for seed, and last year Alberta beekeepers transported 70,000 hives of honeybees to the southern part of the province to pollinate that crop, said provincial apiculturist Medhat Nasr.

“If we don’t have these kind of pollinators, the yield of hybrid canola seed production would go down by 90 per cent,” he said.

But mixing in wild bees is best, he said, because there’s a “synergy” between their work. If a variety of different bee species visits the same flower, it increases the odds of pollination occurring, he said.

But the wild population has been going down, Nasr said.

“It’s declining because there’s not enough wild flower forage sources for them around,” he said.

Alberta Agriculture has been encouraging the public and municipalities to develop more natural habitats for these insects, he added.

“Instead of growing just grass, why not grow some flowers which will bloom at different times of year that will make food sources available to honeybees as well as wild bees?” he said.

There’s better news on the honeybee front, despite the ravages of colony collapse disorder. The provincial honeybee population dipped to 220,000 hives in 2007, but rebounded to 282,000 hives last year, he said.

“We are working towards solving the problem,” he said. “We have a successful example in honeybees and I’m sure it’s going to be successful also for wild pollinators.”

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