Canola School: A insect pest forecast for the Prairies

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The impact of 2021’s drought and heat across many parts of the Prairies continues to be a key point in conversation as we look towards the 2022 growing season.

Meghan Vankosky, field crop entomologist with Agriculture and Agri-Food Canada (AAFC) based at Saskatoon, Sask., recently spoke at Alberta’s Agronomy Update to discuss the impact the heat and drought had on insect pests of the prairie crops.

Many questions have come in from producers since last summer, says Vankosky, about how this period could affect insect populations. When it comes to canola, specifically, it’s a mixed bag of good news and bad news for crop production. For the purpose of this Canola School episode, we focused on the top insects: flea beetles, grasshoppers, swede midge, and pollen beetles.

The models Vankosky et al. used to form some predictive maps for these insects, are based on the average conditions from the last 30 years. As well, Vankosky says insects take time to respond, so it’s key to keep that in mind when creating forecast maps, as some may respond quickly in one growing season, while others take a few growing seasons to respond. (Story continues below video)

Flea beetles

Across the Prairies we deal with two flea beetle species, the crucifer and the striped flea beetle. Fortunately — they both react different to hot and dry conditions, says Vankosky.

“Crucifer flea beetles do quite well when it’s hotter and drier, and striped flea beetles actually prefer it to be cooler and wetter,” she explains. “So in prolonged drought and hot conditions, we might actually see a decline in that striped flea beetle population, at least in the end of their pest status as a result of that. Whereas crucifer flea beetles are likely to respond in the opposite way, and may become more of a problem in hot and dry conditions,” she adds noting that flea beetles only have one generation per year.

Grasshoppers

When we think of hot and dry, we can’t help but talk about grasshoppers. And as many discovered in 2021 — canola is not immune to grasshopper populations.

“This is a species that does only have one generation per year again. But we know from a multitude of research across the prairies, by a number of different people that in hot, dry years, grasshoppers develop faster so they start laying eggs earlier. And over the course of a couple of years of hot and dry conditions, grasshoppers develop faster so they start laying eggs earlier. And over the course of a couple of years of hot and dry conditions, grasshopper outbreaks can build up very quickly,” she explains. “They do like, or will eat canola. And I think a big part of that is if it’s dry, they’re looking for water and canola is very nice and juicy. So we do see quite considerable damage to canola crops and to certain pulse crops, too.”

It’s also important to note that for 2022, we’re still looking at a patchy outbreak level, but we are trending towards a more regional outbreak if we experience the same conditions, says Vankosky.

Swede midge and pollen beetle

Although the swede midge and pollen beetle are not established pests on the prairies yet, they are present in other parts of Canada and in the East, emphasizes Vankosky. Which is why many entomologists are on the watch for these invasive species, as they could turn out to be quite devastating for canola production.

“Swede midge especially do not respond well to drought conditions or to really hot conditions, which is a great news story for the Prairies. But if things get hotter and drier, that pest potential area really drops to nothing, which is a very good news story, because swede midge have been just devastating to canola production out East,” she explains.

Pollen beetle is another insect that isn’t established in Western Canada, but definitely needs to be looked out for.

“In the current climate, based on that 30 year average, there’s actually quite a large portion of the prairies that could experience damage from pollen beetle infestation, but in a hotter and drier climate, over a couple of years of drought we actually see their region shift northward to where it’s a little bit cooler and wetter,” says Vankosky. “So pollen beetle aren’t responding very positively to hot and dry conditions, but they’re not as sensitive to those hot and dry conditions as the swede midge for example.”

Other Episodes

Canola School (view all)Season 14 (2022) Episode 5

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