Pine Beetles: Out of the Forest, Into the City

Bob Lalonde and Rebecca Tyson are trapping mountain pine beetles to better understand how they move through urban areas - photo by Jody Jacob
Bob Lalonde and Rebecca Tyson are
trapping mountain pine beetles to better understand how
they move through urban areas – photo by Jody Jacob

UBC Reports | Vol. 54 | No. 11 | Nov.
6, 2008

By Jody Jacob

Mountain pine beetles are sweeping through British Columbia’s
vast forests with highly destructive results, but their mass
attacks don’t stop at the edge of town.

Working in one of B.C.’s latest beetle battlegrounds
— the city of Kelowna — UBC Okanagan biologist Bob
Lalonde and mathematician Rebecca Tyson are combining their
expertise to track how the mountain pine beetle spreads through
an urban landscape during a mass infestation. Although extensive
research has been done on the mountain pine beetle in a forest
setting, there is very little information on how they work
their way through a city, says Lalonde, Associate Professor
of Biology and Physical Geography.

“Essentially, we have an empty playing field to conduct
our research,” says Lalonde. “This summer, a
mammoth infestation of mountain pine beetles arrived in the
City of Kelowna, creating an interesting opportunity to pursue
the beetle’s movements in an urban landscape from the
beginning of an infestation. As you can imagine, many people,
organizations and municipalities are interested in the project.”

In May, Lalonde and Tyson, with the help of two summer students,
strategically placed 44 pheromone traps — which attract
and capture beetles — around the outskirts of Kelowna,
as well as in the centre of the city.

“Basically we are trying to determine how the bark
beetle enters the city, what direction they are entering
the city from and how they move while in an urban environment,” 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.”

Checked every week until their removal in mid-August, the
pheromone traps contained anywhere from zero to 200 mountain
pine beetles, depending on location, as well as pine beetle
predators, providing data that can help determine how quickly
predators follow the bark beetles into the city.

The next step in the research is to analyze samples and
data collected over the summer and use the information to
create a mathematical model that identifies dispersal patterns
of the beetle. A number of variables will be considered,
such as location of the traps, number of beetles trapped,
number and concentration of pine trees in the general area,
biology of the beetles, and weather conditions.

“Mathematical modeling often reveals interesting behaviors
that aren’t anticipated,” says Tyson, Assistant
Professor of  Mathematics, Statistics and Physics. “We
are using beetle biology, spatial data and math in an attempt
to understand in greater detail how the beetle is moving
through an urban landscape, 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

Although the mountain pine beetle infestation reached the
city of Kelowna this summer, it will take a few months before
the severity of the damage to the city’s trees is known.
Lalonde and Tyson are working with the City of Kelowna to
identify the areas most affected, and will use that information
as a variable in the mathematical model. Next year, they
plan another summer of data collection, which may focus on
determining how many beetles are originating from areas within
Kelowna as a result of this year’s infestation, as
opposed to how many are still moving into the city.

“We are really just at the beginning stages of the
project,” says Tyson. “There is still a lot
of data to be collected and analyzed. One thing we can say
with confidence though 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.”