Emerald ash borer able to withstand cold up to –40 C, new research indicates
CBC
Scientists in Sault Ste Marie, Ont., have made a discovery about the emerald ash borer that could help assess future risk to the region's — and Canada's — threatened ash trees.
Amanda Roe, a scientist at the Great Lakes Forestry Centre, studied how the ash borer was able to survive extreme cold temperatures and adapt its physiology to severe Canadian winters.
The study, titled "Plasticity," was published in Current Research in Insect Science. Co-authors include Meghan Gray and Chris MacQuarrie from Great Lakes Forestry Centre, and Meghan Duell and Brent Sinclair from Western University in London.
Roe said the researchers isolated beetle larvae to study how they reacted under extreme cold temperatures similar to those in Canada, specifically, icy Winnipeg temperatures.
"These larvae actually can survive really cold temperatures, and they do that by keeping their blood from freezing," Roe said.
"As long as their blood stays liquid, they will survive, and they do that by using antifreeze … they use glycerol."
The larvae Roe tested survived through –40 C, with one beetle surviving into –50 C, before freezing and dying.
"They're significantly more cold tolerant than anything we'd seen before," she said.
The amazing part, Roe said, was the beetles harvested from Winnipeg appear to be adapting to their location, becoming more acclimatized to deep dips in the temperature.
"These bugs from Winnipeg, if they're given a southern Ontario winter, they behave like other bugs from southern Ontario, so they don't get that cold," Roe said.
"But those Winnipeg bugs, if they experience a Winnipeg-like winter, they are the ones that are able to get those really low survival temperatures."
Roe said that means the emerald ash borer can adapt its physiology to the conditions the bug is experiencing.
"They're responding in a flexible way," she said. "It's priming them to be able to survive those more extreme temperatures."
And that's not good news for Canada's ash tree population.