By: The Working Forest Staff
UNIVERSITY OF ALBERTA — In a new study aimed at assisting efforts to contain the destructive spread of mountain pine beetles, University of Alberta biologists examined their flight techniques and used genetic information to track how they are spreading through the province.
“One of the reasons these beetles have become such a problem is because of the difficulty in controlling them, as their dispersal is very hard to predict,” said the study’s lead author, Victor Shegelski, who conducted the research as part of his PhD studies in the Department of Biological Sciences. “Some beetles disperse using their own flight power below the forest canopy, but others will catch updrafts, and they literally go wherever the wind takes them.”
This mode of travel is how beetles arrived in northern Alberta in the first place, over the Rocky Mountains. The researchers found that many of these beetles are likely also travelling large distances within Alberta, potentially within a single year. Based on genetic evidence, the beetles spreading through central and northern Alberta are coming from two different populations: one that entered Alberta through the Grande Prairie area and the other through Jasper, with the beetles from the Jasper population potentially traveling hundreds of kilometres to the northeast.
Shegelski, now the assistant curator at the U of A’s E.H. Strickland Entomological Museum, explained that to assess beetle flight capabilities for his PhD, researchers placed beetles on “flight mills”—tiny mechanisms similar to spinning treadmills that allow a beetle to fly as fast and as long as it wants to. The researchers then collected DNA samples to track the spread of beetle populations through the province.
Stopping the spread
Mountain pine beetles can be an important contributor to forest health; normally they attack older, weaker trees, making room for new growth in the forest. But when they spread to an area with a large number of older trees, their populations explode—and once populations are big enough, Shegelski explained, they start attacking younger, healthier trees, further perpetuating the cycle.
“Once they switch into this kind of behaviour, it can be very difficult to stop. That’s why it’s critical for us to understand the mechanisms behind their flight and dispersal across the landscape.”
If we continue to increase our understanding of these beetles and continue to focus control where it will be most effective, we can certainly prevent a lot of damage going forward.
(Photo: Dawn Graves)
In the last two years, the researchers have seen some positive signs despite the beetles’ aggressive spread. Colder weather causes many beetles to die while overwintering and cool, wet weather can limit their dispersal, meaning less reproductive success.
“We are seeing signs of them slowing due to the last two cold winters and wet springs and summers. So the story definitely isn’t all doom and gloom,” said Shegelski. “These beetles may also have a hard time using the new pine tree species they encounter as they move eastward.
“Alberta’s control efforts have kept the beetle from becoming an even greater problem than it currently is. If we continue to increase our understanding of these beetles and continue to focus control where it will be most effective, we can certainly prevent a lot of damage going forward.”
The study, “Source and spread dynamics of mountain pine beetle in central Alberta, Canada,“ was published in The Canadian Entomologist.