Pheromones

Pheromones are chemicals released by one individual to communicate with another individual of the same species. Spruce beetles release a “mass attack” pheromone to signal to other spruce beetles in the area that good host material is nearby. They can also release an anti-aggregation pheromone called "MCH" when there are enough beetles and no more room in the host, almost a “no vacancy” warning. Synthetic formulations of the anti-aggregation pheromone have been developed and studied for use as a repellent against spruce beetles. Results have been mixed on the efficacy of these products in Alaska, and issues with protection tend to be related to the rate of release and zone of protection for individual trees or wide-area protection. Improvements to dispensers are ongoing as are efforts to test their effectiveness in Alaska.

Solarization, Tarping

Solarization, or covering wood piles with plastic to trap heat, has not been proven successful in Alaska because it does not get hot enough to create enough heat within the pile to kill the beetles. This is another area where more work could be done in Alaska to refine the recommendations. Initial tests were completed on the Kenai Peninsula in the 1990’s. As temperature trends change, reviewing this work and testing in other parts of the state could provide additional information about this strategy as an option.

fire wood pile covered in tarp. Joseph OBrien, USDA Forest Service, Bugwood.org Solarization is not effective in Alaska, the pile does not get hot enough.

(Joseph OBrien, USDA Forest Service, Bugwood.org)