An entomologist with Ontario's Ministry of Agriculture is warning farmers to not be lulled into a false sense of security by thinking insects have been killed off by the extremely cold winter.
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Tracey Baute says farmers may be hoping to see less harmful insect activity during the growing season. Don't count on it, says the provincial field crop entomologist.
"Though overall there could be a reduction in pest populations, this is not necessarily true for all of our key pests," Baute said in a post on her website, Baute Bug Blog. "Some of them are quite tolerant to harsh winters and deal with it better than we do."
In her post, Baute said insects have three main strategies to battle the cold:
- Some look for warmer climates. The black cutworm migrates to the southern U.S.
- Others stay put but avoid the freezing temperatures by moving below the frost line in soil or going indoors to overwinter.
- Some simply tolerate freezing temperatures by using antifreeze compounds in their system to prevent cells from freezing and bursting.
"Both wireworms and grubs know enough to move down deep below the frost line," Baute writes. "Though I haven't experienced a year before where there were reports of frost quakes taking place. That tells me that it got quite cold, deeper down than usual."
As overnight temperatures in Toronto dipped to -20 C on Jan. 2, several people reported hearing loud booms, which CBC meteorologist Jay Scotland said was likely the result of a "frost quake."
The boom is caused during a cryoseism, a weather phenomenon called , often referred to as an "ice quake." They happen when water in the ground expands in extreme cold.
Baute said bean leaf beetles, flea beetles and slugs overwinter closer to the soil surface and "may have had a harder time dealing with this winter."
"They likely took more of a hit," Baute wrote.
She said predators of those insects have also likely struggled to survive "since they are also usually close to or above the soil surface for winter."
Farmers still expect 'good kill'
Lyle Hall, president of the Essex County Federation of Agriculture in southern Ontario, is one of those farmers who believes the harsh winter will lead to "a good kill on pests."
"Usually, a good, hard, cold winter like we've had this year will do most of the pest in," he said.
For example, Hall doesn't expect soya aphids to survive.
Harold Wagner, who owns an apple orchard east of Windsor, Ont., also believes a cold winter is a good thing.
"Usually winters like we've had, have a great cleansing effect on the environment," he said.
Extreme cold swept across Ontario this winter.
Windsor, Ontario's southern-most city, shattered its snowfall record this year. It also set record-low temperatures on several days in January. Ottawa, meanwhile, registered its coldest St. Patrick's Day in history and Thunder Bay experienced its coldest winter on record.
Baute said predicting which pests are going to be a concern each year is "a bit of a crap shoot."
"Spring conditions play just as big of a role as to which pests win," she said.