Researchers discover key gene involved in bark beetle pheromone production

June 28, 2005

Findings may lead to new methods to control beetles, which have decimated Lake Tahoe and Western forests
University of Nevada, Reno scientists have ended a decade-long controversy over the process by which bark beetles make pheromones: they manufacture their own monoterpenes - the fragrant substances plants produce and which are often used in perfumes. It had been thought that insects and other animals were incapable of making these substances.

"The goal of our research is ultimately to control pheromone production," said Gary Blomquist, professor and chair of biochemistry and molecular biology, who co-authored with several members of his department an article that will be published this week(June 27 - July 1) in the Proceedings of the National Academy of Sciences (PNAS).

Bark beetles plague pine forests, especially when the trees are stressed. The Lake Tahoe basin lost 30 percent of its pines to bark beetle infestation during the 1986-1994 drought, according to Blomquist.

There are several hundred species of bark beetles, which are in the insect family Scolytidae. These beetles are difficult to control via insecticides because they live almost all of their lives, from eggs to adults, burrowed under thick bark where they are protected. Only for a few hours do they fly from one tree to another to join other bark beetles, mate and start a new life cycle.

But other bark beetles know where to locate mates because they are responding to an "aggregation" pheromone. If this pheromone could be disrupted, the beetles wouldn't be able to organize a "mass attack" to successfully colonize a tree, and they would die.

University researchers have characterized the key gene in the beetles' monoterpene biosynthesis, which will allow further research into ways to disrupt the production of aggregation pheromone.

In addition to Blomquist, Anna Gilg, Jeremy Bearfield, Claus Tittiger and William Welch co-authored the article, "Isolation and functional expression of an animal geranyl diphosphate synthase and its role in bark beetle pheromone biosynthesis."

University of Nevada, Reno

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