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If you were hoping Nova Scotia’s relatively snowy winter will mean there are fewer ticks this year, experts warn you may be disappointed.
Deep and long-lasting snow can actually be a help, not a hindrance, to these hardy insects, say tick researchers.
“That deep snow cover really is providing a big layer of insulation for them,” said Laura Ferguson, an assistant professor in the biology department at Acadia University. “So they’ve been fairly protected.
“I anticipate that probably, you know, we’ve got such a big population of ticks that a good portion of them have made it through this winter and we’ll see them again pretty soon here.”
CBC meteorologist Ryan Snoddon said while Nova Scotia had some cold snaps in December and the first half of January, our most sustained tick-killing temperatures arrived after there was already snow on the ground to protect them.
There was constant snow on the ground at the Halifax airport from Jan. 18 to March 21, a streak lasting 64 days in total. That’s the longest stretch of snow cover at that location since the winter of 2020.
Ticks seek sheltered places such as underneath leaf litter to hunker down for the winter. They do not need to eat for months at a time, and in fact, their metabolism slows down to such an extent in very cold weather that even if a luscious host — a bare human leg or a dog, for instance — brushed past them, they may be unable to move to benefit from the opportunity.
Ferguson said ticks can survive weeks or months in 0 C to –5 C weather. Consistent temperatures below –10 C without the protection of leaf litter or snow can cause mortality, as can sudden ups and downs in temperature.
If ice forms inside their bodies, it can damage their tissues and kill them.
Jantina Toxopeus is an associate professor in the biology department at St. Francis Xavier University and has been researching how temperature affects ticks.
Toxopeus said they usually freeze at temperatures lower than –15 C, at least in a lab.
However, she said how quickly the temperature drops makes a difference. Much like the proverbial frog in boiling water, they seem to be able to adapt better to slower changes.
“If it’s a shock, if it’s like a real quick temperature change, they seem to struggle,” Toxopeus said. “But then we tried some slower ramps down to –10 C and they were actually OK.”
She said most people think that extreme low temperatures will kill an insect, but ticks “deal with cold pretty well.”
Toxopeus said a few years ago, Nova Scotia had extreme cold temperatures of –27 C, but she didn’t notice any dip in the tick population afterward.
“So yeah, the ticks seem to be doing just fine,” she said.
Ferguson said she doesn’t expect this year’s tick season to be any better or worse than previous years.
“We’ve got a pretty robust, hardy population,” she said. “I imagine it will be more or less the same as it has been for the last several years.”
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