Will extreme cold slow ash borer? Don’t count on it.

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Sylvie Filion


Sylvie Filion

The emerald ash borer has been in the news since 2002, when it was first   discovered in the ash trees of Southeast Michigan. Since then it has destroyed 150 to 200 million trees in North America; it was discovered in Shawville late last year. The insect lives just under the bark and can survive through the cold weather by producing glycerol, a kind of antifreeze. Over its 15,000-years of evolution the emerald ash borer has developed great tolerance to extreme colds.
Brent Sinclair, biology professor at Western University, explains that the insect’s larva has a waxy covering preventing ice crystals from penetrating them. The insect then produces glycerol which has the same characteristics as the  antifreeze we use in vehicles, except that it is non-toxic. The emerald ash borer is therefore protected against extreme cold.
Robert Venette, co-author of an American Forestry Department study, has recently discovered that this protection may not be fool-proof. The study indicates that as  temperatures become extreme, the glycerol loses some effectiveness. “If the insect freezes, if ice gets into its body, it will die,” says Venette. According to this expert, the emerald ash borer tends to die quicker when temperatures are between – 28.9 and – 34.4 ⁰C. “A slight change in temperature can result in record death rates,” he adds.
On the other hand, Anthony Daniel, a Montreal biologist, is more inclined towards the theory of high tolerance to extreme cold; he says the emerald ash borer          survives in northern Russia.
“The emerald ash borer larva not only have the waxy covering and the glycerol to protect them, the insect also synthesizes small amounts of poly  peptides present in the blood; these are proteins that adhere to the ice    particles and prevent   crystallization,” explains Daniel. “Studies were done in recent years showing that the emerald ash bore survived extreme cold, even when temperatures warmed up and then went down again.”
The insect seems to be here to stay, although     scientists have not given up the battle against them.