Cold weather likely did little to harm ticks

An adult female, non-engorged, Ixodes scapularis, or black legged tick. If you’re wondering whether recent frigid temperatures might have killed some of the tick population, you’re out of luck, according to Mount Allison University biology professor and tick expert Dr. Vett Lloyd. (Contributed)
As if the wacky weather merry-go-round hasn’t ticked you off enough, it appears the deep freeze/warm weather cycle has done nothing to mitigate the creepy crawly population, either.

Double-digits in the minus column do little to bug ticks, according to an expert with Mount Allison University’s tick and Lyme disease research centre, especially if there’s an insulating snow cover.

Without snow, some of the adult arthropods might have bit the dust if they got cold enough for a long enough time, but there’s no real reprieve from mother nature, said Dr. Vett Lloyd, a biologist in the university’s tick lab.

“It’s an interesting interplay between the snow and the cold,” Lloyd said in a telephone interview. “So, in New Brunswick and, it looks like, Maine, we had our snowfall before it got cold, so the ticks are just going to be happy as anything in the leaf litter under the snow. Nova Scotia’s an interesting question — and the same is true of P.E.I. (There’s) less snow for you guys, so the ticks at the surface might have frozen. The trick is, though, how cold it has to be and for how long to kill a tick.”

According to Environment Canada’s online historic weather data, between Dec. 27 and Jan. 3, temperatures at the Halifax Stanfield International Airport held consistently below -10C and ranged down to lows of -16C before warming up to above the freezing mark again on Jan. 4.

“So, to kill the eggs, you’ve actually got to get it down to minus 30-some degrees,” Lloyd said.

“That’s pretty cold. And the eggs, they’re not laid right on the surface, they’re usually down a little bit, just in the leaf litter. So the eggs are perfectly fine, unfortunately for us. The adults freeze much sooner. They’ve got kind of an antifreeze in their body. But they’ll be good to -10, -15. But the air temperature is always colder than what it is under the leaf litter, so maybe we lost some adults but the next generation’s going to be OK.”

One adult female tick can lay between 2,000 to 5,000 eggs and while the mortality rate of a batch of larval ticks can be 80 to 89 per cent, when you start with thousands, that still leaves a lot.

“They’ll (only) do one generation of offspring, so that’s a bit of good news,” Lloyd said. “The female dies after she’s laid eggs. It’s a one-shot deal.”

It gets even worse, though. When the temperatures rise above freezing, the little buggers can come out looking for blood, again. Even in January. So if you were out in the prime tick areas, you should check for unwelcome hitchhikers.

“Whenever we get these little thaws, we suddenly get an upsurge in people finding ticks on their dogs or cats or, unfortunately, on themselves,” Lloyd said on Friday. “I did it this morning, it was a lovely day, (I) went out for a walk and all of a sudden realized, yeah, I need to be checking myself for ticks again.

“It may be January but the ticks don’t know that.”

She said New Brunswick and P.E.I. will see ticks 10 out of the 12 months of the year.

“We certainly get them straight through to December and they usually pick up in about March. (In) Nova Scotia, your season would be a bit longer. It’s that much warmer. They’ll probably be starting up in February.

“So, for people with dogs, it’s a good idea to keep the tick repellents and the tick medication going year-round and for the people who work outside, keep checking yourself for ticks.”

Nova Scotia has “a good diversity of ticks,” Lloyd said, including the black legged ticks that can carry Lyme disease.

“There have always been ticks here, they have not always been the black legged ticks. Those have always been introduced from the States on migrating birds when they come north in the spring, but when the climate was cooler, they’d mostly die off in the winter and with climate change, now they’re not dying off. They’ve settled in and they’re quite happy here.”

It seems the little suckers have a varied diet when it comes to who and what they’ll latch onto.

“Ticks, particularly the black legged ticks, are not specialists, (although) some of the other ones are,” the researcher said. “So, if you’ve got blood, you’ll work just fine for them.”

And it doesn’t have to be summer, either.

Source: http://thechronicleherald.ca/novascotia/1536665-cold-weather-likely-did-little-to-harm-ticks

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