Forest

Gary Blomquist and Claus Tittiger

Gary Blomquist

Gary Blomquist and a graduate assistant
removing a portion of a beetled-killed tree
to extract the pine bark beetles.

Pheromone biosynthesis in pine bark beetles
Bark beetles are the most destructive pests of sawtimber and pulpwood in the northern hemisphere. Attacks on North American forests lead to billions of cubic feet of timber loss every year. Bark beetle killed trees are a major factor in increasing the fuel load contributing to the devastating wild fires experienced in our national forests and urban-forest interfaces. 

The bark beetle problem is likely to get worse with the predicted climate changes.  With droughts and balmier winters, bark beetles have proliferated, expanding their geographical range, killing and turning to kindling millions of trees in North America. In Little Valley, the mountain pine beetle, the Jeffrey pine beetle and the pine engraver beetle are a threat to lodgepole and Jeffrey pine.

The long-term goal of our research is to develop new and effective pest management tactics based on insect pheromone systems. Bark beetles are physically protected beneath the bark of the trees that they colonize and kill for most of their lives, except for the short, pheromone- mediated flight from brood trees to new trees under attack, making disruption of pheromone communication an attractive target for insect control. To fully exploit pheromone-mediated bark beetle behavior from a management standpoint, a thorough understanding of the origin, expression and activity of these chemical signals in the target species is important. Of particular interest is how the critical enantiomeric blend of pheromone is achieved. Fundamental research on the biogenesis of bark beetle pheromone production may lead to the development of new treatments that will enhance the productivity of our nation's forests.

The work from the Blomquist and Tittiger laboratories has resulted in a paradigm shift in our understanding of pheromone production in bark beetles.  Before our work, it was widely believed that most of the bark beetle pheromones were derived from host tree precursors, and the beetle only minimally modified monoterpene precursors to produce pheromone components. Our work demonstrates that bark beetles produce most of their pheromone precursors de novo from acetate and biosynthesize many of the pheromones in midgut tissue. Using a genomics approach, we have identified many of the key reactions in pheromone biosynthesis in bark beetles.

Beetle-killed Jeffrey pine trees

Beetle-killed Jeffrey pine trees

Pine bark beetles under the bark of a Jeffrey pine tree

Pitch tubes on the bark of a Jeffrey pine

Pitch tubes on the bark of a Jeffrey pine, evidence that beetles have entered the tree and are feeding on the phloem under the bark.