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A few tweaks to farm landscape management can improve life for beneficial insects

It’s estimated that insects such as bees are responsible for pollinating almost 20 per cent of Canada’s crop, but that’s not the only reason for protecting their habitat. It’s also a breeding ground for beneficial insects that prey on cereal, oilseed and pulse crops. A recently completed study shows that simply “tweaking” agronomic practices can incorporate pollinator-friendly features on the farm.

“About 30 per cent of the farm area needs to be under natural cover to support pollinator populations,” says Melanie Dubois, an Agriculture and Agri-Food Canada riparian and biodiversity biologist in Brandon, Man. “But that doesn’t necessarily mean you need to take 30 per cent of your operation out of production.”

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Dubois says it does mean looking at any areas that can support bees — such as shelterbelts, filter strips, flowering hedgerows, yards, field margins and ditches — and asking how these areas can be managed to support pollinators.

This can include planting native flowers and resisting the urge to mow areas that are home to flowering plants.

“Sometimes it’s just a matter of looking at what you’re already doing and how you can tweak it,” she says. “These are working landscapes and we have to make sure the practices that we’re recommending are sustainable.”

Pollinator habitat is an increasingly buzzworthy topic in Canada. In 2016, General Mills, the Xerces Society and the United States Department of Agriculture launched a campaign to restore or establish 100,000 acres of pollinator-friendly habitat across the U.S. and Canada, focusing on Manitoba oat producers.

In 2017 Syngenta and the Soil Conservation Council of Canada introduced Operation Pollinator, a program that provides seed and technical and financial support to producers looking to improve pollinator habitat.

Operation Pollinator is a Syngenta program focused on research and partnerships to promote the health and well-being of bees and other pollinators given their essential role in agriculture and nature.
photo: Syngenta Canada

Dubois just wrapped up a three-year study focused on pollinator habitat at the Brandon Research and Development Centre.

She says there’s some cross-pollination between projects — for example, Dubois matched General Mills/Xerces with Manitoba producers and conservation districts for their habitat campaign, and her project used Xerces’ habitat-testing and assessment tool — but the work is only beginning in Manitoba.

As results roll in, researchers are making some surprising discoveries. For example, Environment Canada’s oft-cited 2015 Wild Species publication reported that Manitoba is home to 236 bee species, says Jason Gibbs, a University of Manitoba research biologist who collaborated with Dubois on her study.

But based on newer data, Dubois and Gibbs say that number is closer to 360.

“That’s opening our eyes to the scale of the diversity and to which species are present and which ones we need to protect, which are rare and which are common, and how the species vary by land use types,” says Gibbs. “There’s a lot more bee diversity in Canada than anyone had understood.”

Study results

Dubois’s study was conducted on 36 sites within an hour and a half drive from Brandon. The researchers attempted to recreate native bees’ preferred habitats in field boundaries by planting perennial native flowering plants that don’t interfere with bees’ appetites for pollinator-dependent crops such as canola.

The team also conducted habitat assessments, which included an inventory of plant types and size and distribution of food and nesting locations near the trapping sites, and they sampled bee populations in fields adjacent to canola crops.

Over the life of the project, Dubois and her collaborators caught just under 30,000 bees. Most were sent to Steve Javorek, an AAFC biologist in Nova Scotia, for DNA barcoding, a method that uses a genetic sequence from a tissue sample to identify and “barcode” unique species.

Critically, Dubois’s team also evaluated farm management practices for their impact on pollinator habitat.

Dubois says that when researchers talk about bees, they’re mainly talking about native bees versus honeybees, “which are like livestock and are intensively managed,” she says.

Researchers collecting insects in a ditch alongside a canola field. Other areas such as shelterbelts, filter strips, flowering hedgerows, yards and field margins can be managed to support pollinators.
photo: Melanie Dubois, AAFC

But native bees, which perform most pollination in Manitoba, are wildly diverse, with different lifestyles and nesting and vegetation needs.

“About 80 per cent of our bees are ground nesters and they need undisturbed well-drained bare soil. Looking at the extent of agriculture in Manitoba, you can see why that’s critical for bees. Every time the ground is tilled it destroys those nests,” she says.

Nesting habitat is one side of the coin for bee survival; food is the other. Some bees are specialists, relying on a limited number of native plants for food. Others are generalists and can feed on a range of plants.

Bees require different shapes of flowers — flat flowers versus cone types, for example — as well as a range of colours. They also require flowering plants through the season.

“The key thing for pollinators is that they need food for the entire flying season, from April through October,” says Dubois. “Spring is a challenging time. We did assessments in spring, summer and fall to see if there was food available all year-round, and what type of food was available — are there the species our native plants are looking for?”

Dubois’s team used lists of plant species required by Manitoba bees created by Diana Bizecki Robson, curator of botany at the Manitoba Museum. Using these lists, Dubois’s team zeroed in on “high-value” native plants to use in the study. But sourcing seed for these plants is a huge challenge without commercial demand, which means some specialist bees are simply out of luck.

“As habitat declines in quality and amount, we’re losing plant species, and when we go out and sample and we don’t find particular bees, it’s not surprising. We’re selecting for larger bees and native plants are losing their main pollinators. Once you lose a pollinator, that’s just another stress on our native systems,” she says.

Management

Dubois says farmers looking to improve pollinator habitat on the farm need to focus on getting flowers into any areas that can support bees, from hedgerows to yard sites.

“If you have just brome, that’s doing nothing for your bees,” she says. “How can you increase the amount of flowers?”

She points to Xerces and General Mills’ tally of innovative ways to incorporate flowers into field boundaries as well as into the field itself via the use of cover crops such as flowering legumes.

“There are all kinds of ways to get those plants in there. You don’t have to think in terms of managing the site with burning to recreate past prairie conditions or putting in 100 per cent native plants,” says Dubois. “You just have to ask, ‘Can I throw some extra flower species in there? Can I avoid mowing? Or maybe I’m mowing at the wrong time?’ Think simply.”

If it’s necessary to mow an area, Dubois says, leave an adjacent section untouched so bees can move to those flowers.

University of Manitoba researcher Gibbs adds that producers should minimize broad-spectrum insecticide use as much as possible. “If you have to spray it, spray it when the crop isn’t in flower, or at night when the bees are back in their nests,” he says.

He also suggests leaving unproductive or treed areas, wet patches or other areas not yet being used for agriculture untouched wherever possible. “There might be unforeseen consequences to removing these,” he says. “As agriculture gets more industrial, the spaces between flower patches become increasingly distant. We need to make sure we don’t lose habitat we still have.”

“Common beliefs that planting native plants in crop margins increases the risk of invasive weed species or insect pests are being debunked,” Dubois says. “New research isn’t seeing elevated weeds in those fields, and it isn’t seeing that bee refugia act as refugia for insect pests,” she says. “On the contrary, they can increase beneficial insect populations in the field as well as protecting pollinators.”

In the next phase of her work, Dubois will partner with AAFC’s Living Labs initiative to take a closer look at the ecological impacts of management practices and how beneficial practices such as adding grassed waterways for erosion control can improve pollinator habitat.

She says protecting pollinators simply means paying heed to the needs of the smallest animals on the farm.

“You have to make sure that if you’re growing a crop that needs bees, they’re around when you need them. And at some point you are going to need them. It’s thinking of them as a resource you need to protect and enhance,” she says.

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Julienne Isaacs

Julienne Isaacs is a Winnipeg-based freelance writer and editor. Contact her at [email protected]

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