Bees Offer Protection Against Crop Diseases and Pests

Flying army carries friendly microbes

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A bee visits a flower.

A bee visits a flower.

We already use bees to help pollinate crop plants while foraging for nectar and pollen. Now University of Guelph scientists and international colleagues are looking to harness pollinators to help farmers protect their crops from pests and disease.

The researchers have shown that bees can deliver “good” microbes – fungi, bacteria and viruses – to protect plants against insect pests and diseases caused by fungi and bacteria. Called pollinator biocontrol vector technology (PBVT), the concept is intended as a green alternative to pesticides and fungicides.

Explaining the basis of biocontrol, Peter Kevan says, “Bees are already carrying pollen and they could be carrying microbes” intended to thwart harmful insects, mites and plant pathogens.

Now professor emeritus in the School of Environmental Sciences (SES), he has worked with researchers at Guelph and elsewhere in Canada, Brazil and Mexico on bee biovectors. They aim to use bees to carry biological control agents to protect crop plants from berries and canola to tomatoes and peppers.

Kevan is director of the Canadian Pollination Initiative (CANPOLIN), a five-year strategic network funded by the Natural Sciences and Engineering Research Council (NSERC) to study pollination in Canada.

Their work with biovectors has led to the first commercial applications being used in the field and in greenhouse crops from the Maritimes to British Columbia.

Broadening the scope, Kevan has now teamed up with Vernon Thomas, professor emeritus in the Department of Integrative Biology, and international researchers to look into biovectors for controlling pests and disease in the worldwide coffee crop.

They’re also working with Les Shipp, a senior research scientist and expert in greenhouse integrated pest management at the Greenhouse and Processing Crops Research Centre run by Agri-Food and Agriculture Canada in Harrow, Ont.

Guelph researchers have tested the technology since the early 1990s, when Kevan first teamed up with Prof. John Sutton, since retired from SES.

In 2003, the researchers showed that bumblebees could be used to control insects, especially the tarnished plant bug, by ferrying the Beauveria fungus. Referring to that organism, Shipp says, “We got the first fungal agent registered in Canada for pest control using bee vectoring. It’s registered now for pest control in greenhouses.”

Along with Guelph grad students, Shipp conducted those tests on peppers and tomatoes in the Harrow greenhouses in the early 2000s.

A Guelph grad, he has been at Harrow since 1987. He and Kevan were part of the NSERC Biocontrol Network to tackle pests and diseases in greenhouses and nurseries.

Kevan and Sutton approached him to work on the project involving greenhouse crops and bumblebees.

Along with grad students and research associates, they have looked at such factors as formulation and optimum concentration. That includes ensuring that the control agent targets pests without harming the pollinator.

Their tests have shown that the technology works against other pests, including aphids, whiteflies and thrips. They have studied the use of both Beauveria and the soil bacterium Bacillus thuringiensis delivered by bumblebees to peppers, tomatoes, strawberries, blueberries and sunflowers.

They have shown that two fungal agents – Beauveria and Clonostachys rosea – can be delivered by bees at the same time to control both insects and disease.

Shipp has also shown that bee biovectoring can complement the use of other biocontrol agents used in commercial greenhouses, such as predatory mites and parasitic wasps that prey on whiteflies and thrips.

He says the technology has moved beyond research into commercial production. “It’s being used. It’s a new technology and, like anything new, it takes time. We have growers using it in Ontario.”

Lots of growers are interested in bee biovectoring, but it’s still early days for the technology, says Kevan. It’s important to get more products registered for use – an aspect that the researchers are still working on.

Bee vectoring can be as effective as chemical spraying, although chemicals tend to work faster than microbial agents, so it’s important to get the bees working early in the growing season. Bees are also vulnerable to weather and may be susceptible to other factors that inhibit foraging or flying outdoors.

Kevan says bee vectoring is no “silver bullet” but is best used alongside other control measures within a holistic pest management program.

The team’s research led to the formation of a company based in Brampton, Ont., called Bee Vectoring Technology Inc. to develop dispensers and biocontrol agents used in hives for dispersal.

This year, Shipp plans to run commercial trials with a baculovirus – a viral agent – and with other potential fungal control agents.

Their work on pollinators for crop protection appeared in an article in International Innovation published late last year by Research Media Ltd.

In a new application, Kevan is now working with Thomas on potential uses of bee biocontrol for coffee. A wildlife ecologist and self-described “closet botanist,” Thomas has long worked in public policy and legislation involving poisoning hazards to wildfowl from lead shot.

Working with Brazilian and Mexican collaborators, the Guelph researchers hope to persuade the world’s coffee growers to consider biovector technology to improve production and to combat threats, such as the coffee berry borer and fungi responsible for various diseases.

“The majority of coffee-producing nations rank pests and disease as their leading problems,” says Thomas.

The group has established ties with the International Coffee Organization (ICO) – what Thomas calls “the OPEC for coffee.” Last year, they co-organized two workshops during an ICO meeting in Brazil.

Funding has come from the International Union of Biological Sciences for pilot studies of PBVT in coffee.

Thomas says the technology should appeal to growers, especially smallholders. “This technology is simple and readily deployable, and has the added benefits of better crops through pollination and honey harvests from beehives.”

At the same time, large coffee companies in North America and elsewhere are seeking ways to reduce environmental impacts while improving socioeconomic prospects for producers.

“Globally, coffee is the second most-traded commodity after crude oil. It represents a vast crop that is in need of new production approaches.”