A Semiochemical Shield for Spruce and Douglas Fir Tress from Bark Beetle Attack

ISCA Technologies proposes to develop MCH REPEL, an innovative solution to manage the Douglas fir beetle (DFB) and spruce beetle (SB), two highly destructive pests of Douglas fir and spruce trees, respectively, across the western U.S. and Canada. These beetles cause high levels of tree mortality, especially during the long periods of drought that have taken place in recent decades, which make trees far more susceptible to attacks by these bark beetles and other harmful insects. DFB is the most important pest of Douglas fir trees in North America, and is found throughout its host's range from the northern regions of Mexico to southern Canada. While impacts of DFB may be minimal when forests are relatively healthy, this beetle's population may increase to outbreak levels following disturbances like wildfires or windstorms, producing widespread mortality even among relatively healthy trees. This occurred following the extensive forest fires in Yellowstone National Park and the surrounding forests of Wyoming: by 1990, virtually all fire-damaged trees susceptible to DFB had been attacked and killed by this pest. The second target species of this project, the spruce beetle, is the leading cause of mortality among mature spruces, afflicting spruce species from Alaska to Arizona. It is estimated that 333-500 million board feet of spruce timber is lost to SB each year, and that over 2.3 million acres of spruce forests were infested with the pest before the end of the 20th century. Such extensive tree mortality can deplete timber supplies, adversely affect levels and distributions of stocking, disrupt management planning and operations, and increase the potential for forest fires by adding an abundance of dry timber to available fuels. Current tactics for managing DFB and SB infestations are very limited, primarily consisting of strategic tree removals (thinning), prescribed fires, and preventative single-tree treatments using large quantities of conventional insecticides. The coordination of bark beetles to colonize and mass attack a host tree is almost all semiochemically mediated. We propose to explore this aspect of the chemical ecology of DFB and SB in order to develop more effective, environmentally safe, and widely applicable management tools to protect susceptible trees. Researchers at ISCA Technologies along with collaborators from the USDA Forest Service will utilize the anti-aggregation pheromone, 3-methylcycolhex-2-en-1-one (MCH), and ISCA will create a new, organic, and long-lasting DFB and SB repellent formulation, MCH REPEL. This product will be designed to release biologically relevant doses of MCH over a sustained period of time (ideally, over 5 months) to disrupt the aggregation behavior of DFB and SB, thereby preventing mass attack and providing season-long protection of susceptible trees. If successful, the development of MCH REPEL to manage DFB and SB will create opportunities for expanding the use of semiochemicals like MCH into management programs for other important bark beetle species, increasing the economic and societal benefits resulting from this USDA NIFA SBIR project.