SAULT STE. MARIE, ON — It is small consolation for Canadians recently suffering the effects of a polar vortex, but frigid weather has given scientists a chance to learn more about the destructive emerald ash borer.
The invasive species was first detected in isolated locations in Thunder Bay in 2016, and has since been found in other areas of the city.
The city's management plan includes treating some of the urban forest canopy, but it also involves removing about 4600 others.
Researchers with the Canadian Forestry Service in Sault Ste. Marie want to know more about how extreme cold affects the emerald ash borer and what impact it might have on the pest's ability to spread.
They're studying beetles captured in Winnipeg, where the pest's presence was confirmed last year.
"We want to know if it has a different cold tolerance from what we know about EABs in southern Ontario," says research scientist Chris MacQuarrie.
"We're also interested in the cold tolerance of the larval stage of the emerald ash borer, because most of what we know now is about the pupal stage," MacQuarrie told Tbnewswatch in an interview this week.
He explained that in some locations, the insect goes through the winter in the larval stage, while in other locations it's in the pupal stage.
How the EAB responds to frigid weather will help scientists better predict the likelihood of its spread in areas where it is currently absent.
According to MacQuarrie, more northerly populations of the emerald ash borer take two years to complete their life cycle, meaning that more of them spend the winter as larvae. In southern Ontario and the U.S., where the EAB has been studied more extensively, most of the colonies take only a year to go through the life cycle, so they spend the winter as pupae.
Information that scientists currently have about the EAB, therefore, doesn't necessarily apply to the situation in colder climates.
MacQuarrie said researchers should be able to use the new data they gather in computer models to better predict the insect's mortality rate during cold weather spells.
"It helps us figure out what the risk is to places where we don't think EAB is yet. If and when we find it, this gives information to managers about how fast a population might grow, and you know how long you have to do something about it and decide on the best tactics."
Previous research has shown that temperatures in the mid-minus 30 range can destroy a large percentage of an emerald ash borer infestation without eradicating it.
