University of Alberta researchers are closing in on finding an effective bait to get ahead of the destructive spread of mountain pine beetle, which is now killing not only lodgepole pine forests, but jack pine.

Nadir Erbilgin, Associate Professor and Canada Research Chair in Forest Entomology in the University of Alberta Department of Renewable Resources, has been investigating pheromones emitted by the pest in North America's lodgepole and jack pine forests.

The compounds are providing insight into how the beetles swarm in destructive numbers in the Canadian boreal forest. The mountain pine beetle has killed lodgepole pine forests in the Western United States, British Columbia, the Northwest Territories, Alberta and could spread east to the Maritimes.

A new U of A study led by Erbilgin and appearing in New Phytologist investigated the tree chemical compounds that play critical roles in the beetle's pheromone production and attraction in both their established lodgepole pine host and in the newer jack pine host.

The research revealed that the beetles emit the same pheromones from both tree species, but found that the females in the jack pine tree emitted more trans-verbenol, a pheromone that initiates the beetle aggregation on host trees. Females lead the first attacks on trees, while sending out pheromone signals for more beetles to join the aggregation.

"Without this initial chemical signalling, the beetles couldn't aggregate on the same tree," Erbilgin noted.

Beetle attacks also induce a release of a volatile tree chemical, 3-carene. Field tests conducted by Erbilgin and his team showed that when 3-carene was added to a mixture mimicking the aggregation pheromone, beetle capture in traps increased.

Understanding the role of pheromones in beetle invasion also allows for quicker monitoring of the insect's activities in jack pine forests, Erbilgin said. "This eliminates the one to two-year gap in diagnosing beetle-killed stands, which don't show up until the dead foliage turns red."

The U of A team's work is focused on fine-tuning baits currently being used in jack pine forests, in an effort to get ahead of beetle infestations. "Right now we don't know how efficient currently available commercial baits will be in catching beetles in jack pine forest, as they were developed to catch the beetle in lodgepole pine forests."

The hope is to have an effective bait developed for use within the next few years.