SUNDRE – While the persistent, multi-year presence of a destructive pest known as spruce budworm has been noted by Alberta Forestry and Parks, an entomologist for the provincial government said the localized impact is not yet considered an epidemic.
“We mapped some minor infestations that are on private land south of the Sundre area,” said Forest Health Specialist Caroline Whitehouse.
“That kind of extends along that narrow band of spruce between the public forest and private land all the way west of Diamond Valley,” Whitehouse recently said during a video interview.
“And then it does peak into the Kananaskis forest area a little bit, but it’s really quite minor in that region,” she told the Albertan.
“From what we’re seeing from our aerial overview surveys – that’s the primary way that we are doing monitoring for spruce budworm – we’re not seeing what we would call an epidemic at this point,” she said.
“When people see things on kind of a local level, that may give them cause for concern to certain degree,” she said, adding the ministry takes a broader scale look at the larger landscape when considering the health of Alberta’s forests.
“We’ll have populations that maybe bubble up in one area, they are a higher density for a couple of years, and then they reduce and then it bubbles up in another area.”
Asked whether there are any regions in the province where there might be an epidemic unfolding, she said the department’s data from 2024 does not indicate as much.
“We’re basically looking at the percent of defoliation on average of the trees in the stand,” she said.
“What would be an epidemic is if you have these really high levels of defoliation concentrated in an area year after year after year that are sort of self-perpetuating,” she said.
But the department – which as a provincial ministry is primarily responsible for monitoring public forests as opposed to private land – endeavours to be receptive to issues brought to its attention, she said.
“We are listening to municipalities and public concern, and we’re following up on our aerial overview survey,” she said, adding aerial monitoring efforts have been expanded in recent years.
“Given the situation that’s been happening since 2018, we have expanded the area that we are serving to kind of help inform our municipal partners as to what is going on at a larger scale,” she said.
“We’re definitely willing to provide guidance to our municipal partners.”
Whitehouse spoke with the Albertan in light of concerns expressed by a local horticulturalist who considers the insect’s ongoing resurgence a “serious infestation.”
Steve Bouchet, owner of Everblue Nursery who first established a plantation near Sundre in 1996, said he is less worried about his own tree farm where he can deploy mitigation strategies to attack the aggressive pest but harbours concern about damage trees in the greater area could suffer.
“That’s probably the biggest kind of fear,” Bouchet said, adding his concerns are two-fold.
The first is from an aesthetic point of view in the sense of the impact on the area’s natural beauty, which provides a crucial draw for tourism.
“But number two, it’s also a forest fire risk. It adds a lot of fuel to forest fires,” he said, referring to what happens when trees eventually die following several years of recurring outbreaks.
“We’re on year five of the cycle,” he said.
“The budworm eats the new growth of the tree, and then it silks down the tree all the way to the bottom and it continues eating aggressively,” he said, adding trees expend a lot of energy every year putting on new growth that just ends up getting ravaged by the bug.
“It gets to a point where the tree runs out of energy to put on new buds and new growth,” he said. “It eventually just kills all the trees; they starve to death and then they dry up.”
An infestation generally stops when there’s little to no foliage left as there’s no more food for the budworm to feast on, he said.
“It’s categorized as a serious pest by the Government of Canada,” he said. “This isn’t a minor thing to deal with.”
So while Bouchet said he has the means to take care of his trees, he worries about the region’s older growth forests being more susceptible.
He said there does not seem to be much will from Mountain View County to take preventative steps. Recognizing there is a cost involved in spraying, he added failure to act could also present long-term repercussions.
“Jasper burned because it was a perfect storm for a fire. And that fire was due to the pine beetle that killed all the pine in the area,” he said, adding dry conditions and the danger of drought only exacerbate the situation.
Bouchet admitted having known very little about spruce budworm when he first came to the area and said he wasn’t even particularly concerned the first couple of years he noticed the bug begin to appear.
“I didn’t take it too serious,” he said. “Last year, all around the farm, the trees were red because they were eaten alive. That made me open up my eyes.”
Expressing gratitude for a reply to his concerns from Mountain View County Coun. Tiffany Nixon, Bouchet said he feels the county should have communicated and coordinated with its counterparts in Rocky View.
“They had the same problem in Redwood Meadows,” he said.
There is an organic pesticide available known as BKT that, compared with chemical sprays, is environmentally sound and effective against the spruce budworm. But there is a limited window of opportunity to act, as the larvae hatch in mid-May, which is when the bug is susceptible to the treatment, he said.
“This is a thing where you have to be preventative,” he said. “If you’re not, you’ll pay the price. And I really hope I’m wrong, by the way.”
When contacted for comment, general manager at West Fraser – Sundre Forest Products Jason Foote said the company has been keeping an eye on another pest of potential concern.
“It’s spruce beetle,” he said. “That’s a different pest altogether.”
Not to be confused with the mountain pine beetle, the spruce beetle has been observed in locations adjacent to the area of the company’s forest management agreement (FMA).
“We’re aware of it,” he said, adding there was no immediate concern.
Mountain pine as well as spruce and even Douglas-fir beetles are naturally-occurring pests that are “always there somewhere,” he said.
“We don’t have any big outbreaks yet, but we’re watching it,” he said about the spruce beetle.
“If it does start to move into our FMA, we’ll have to change plans a little bit.”
The budworm, on the other hand, has yet to present, he said.
“We’re not seeing that in our FMA,” he said. “We have no immediate concerns on (spruce budworm).”
Mitigation strategies must be measured
While there was an uptick in spruce budworm populations observed in 2018 with a bigger increase in 2021, especially in the Bragg Creek area, Forestry and Parks primarily outlines options.
“In 2021 when we had that issue in Bragg Creek, it was really up to the community to make their own decision about whether or not they wanted to take control measures,” said Whithouse.
“We provided our best advice with regards to the assessment of the situation. And then, they made their choice,” she said, adding the decision was made to undertake a spray program.
Although the effectiveness of that effort was not immediately quantified, populations were lower in the following years, she said.
There are a couple of main mitigation methods available to treat spruce budworm. One is a broad-spectrum chemical insecticide that impacts all insects and by extension other species including birds with the potential of toxic exposure to people and even pets. There can also be a backfiring unintended consequence.
“There’s been some research showing that when you do control spruce budworm, sometimes what you do is … reduce the natural enemies and you actually can prolong an outbreak,” she said.
“You really need to assess the situation very carefully, because you have to ensure that the benefit will outweigh the harms.”
But there is a second option that is considered “more quote, unquote natural,” she said, referring to BKT.
The biological agent is designed to exclusively target all caterpillars, which scientifically speaking are categorized as lepidopteran.
“The caterpillars will eat the spores and then ingest those and then it really does a terrible number on their digestive system, and that’s how it kills them,” she said, adding the main drawback is that any other caterpillar species also ends up in the crosshairs.
As well, regardless of what kind of spray is used, the timing must be precise “because not all life stages are as susceptible to it as others,” she said.
“And they’re expensive,” she added.
Whitehouse was also asked whether milder winters have enabled the bug’s population to proliferate.
“When we think about winter temperatures, we kind of relate back to that information about mountain pine beetle where overwinter mortality is really attributed to these really cold temperatures, so therefore warmer winters enable survival,” she said.
“But not all insects are equal in this way,” she said, adding some caterpillar species like spruce budworm go through a life stage that does not benefit from warm spells.
“They’re actually much more adapted to colder winters.”
Recent research conducted on some populations in eastern Canada considered the impact of temperature fluctuations throughout the winter.
“These fluctuations reduce the survival to adulthood overall,” she said, adding temperature swings actually seem to “negatively impact population growth.”
Responding to a question about what increasing numbers might then be attributed to, she said the spruce budworm is a natively occurring forest pest known as an eruptive species that goes through natural cycles.
“We’ve had epidemics in northern Alberta, and then obviously we had a bit of that peak of populations in Bragg Creek,” she said.
“And then populations kind of subsequently decline,” she said.
“It could be that they run out of host at higher population levels, they can transfer viruses and diseases between each other, which kind of help to reduce those populations and maybe cause a higher population density to crash,” she said, adding there are also natural enemies that keep their numbers in check.
Although species such as certain birds or even other insects like flies tend to lag behind the population cycle of spruce budworm, “they can get to the point where they can effectively control those populations as well.”
