Beetling About in Kelowna

When people think about pine beetle infestation, they usually think of vast tracts of dead forest. But pine beetles don’t limit their activities to rural areas, as Kelowna residents can testify. The city was hit with an infestation of the insect for the first time last summer. For UBC Okanagan researchers, this presented an opportunity to learn how the beetle moves and spreads through an urban area.

Bob Lalonde and Rebecca Tyson combined their expertise in biology and mathematics respectively to gather data and build a mathematical model that can identify dispersal patterns. “We are
trying to determine how the bark beetle enters the city, what direction they come from and how they move in the city,” says Lalonde. “In addition, we plan to study the beetles themselves and look at factors such as how much energy is being burned in their flight path.”

With two summer students, the researchers placed 44 pheromone traps around the city and its outskirts. They were left for two months and checked every week. Depending on location and the prevalence of natural predators (the work should also shed light on how quickly beetle predators follow their prey into new areas) the traps contained anywhere from zero to 200 beetles. Other variables used to create the dispersal model include concentration of pine trees, beetle biology and weather conditions.

“Mathematical modeling often reveals interesting behaviors that aren’t anticipated,” says Tyson, an assistant professor of mathematics, statistics and physics. “We are using beetle biology, spatial data and math in this research, which may help us gain insight into the risk of infection for pine trees in certain areas of the city. This could result in possible solutions or preventative measures.”

The team plans more data collection this summer. This time, the data may help reveal the number of beetles originating from the city rather than entering it. “There is still a lot of data to be collected and analyzed,” says Tyson. One thing we can say with confidence is that, based on early results, it looks as though bark beetles enter a city from the outskirts inward, as opposed to dropping randomly from above, as some people had originally suggested.”

UBC Alumni’s Trek magazine Issue 23, Spring 2009 p 11