A study uncovers insights into bark beetle pheromones that could improve efforts to predict the unfolding of outbreaks. Mountain pine beetles (Dendroctonus ponderosae) have infested more than 25 million hectares of western North American pine forests, posing an epidemic threat to forest ecosystems. Female beetles burrow into the barks of pine trees to mate and lay eggs, and developing larvae gradually gut the trees. Previous studies have found that when female beetles attack a new tree, they convert the pine defense compound α-pinene into the aggregation pheromone trans-verbenol, which serves as a cue for the colonization of pine trees. Joerg Bohlmann and colleagues report that male and female beetles accumulate variants of the aggregation pheromone--verbenyl oleate and verbenyl palmitate--during their larval and pupal stages. Whereas females retain the variants when they emerge from brood trees, males lose them as they mature. Exposure to juvenile hormone III triggered a decrease in verbenyl oleate and concomitant release of trans-verbenol from adult females but not from adult males; in contrast, both males and females released trans-verbenol when exposed to α-pinene. The ability of females to produce the aggregation pheromone in the absence of α-pinene suggests that female beetles may harbor a previously undiscovered metabolic reserve of the pheromone that functions as a detoxification system coopted for pine colonization. According to the authors, uncovering the biochemical mechanisms of pheromone release in mountain pine beetles may aid efforts to improve the prediction of outbreaks.
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Article #17-22380: "Monoterpenyl esters in juvenile mountain pine beetle and sex-specific release of the aggregation pheromone trans-verbenol," by Christine C Chiu, Christopher I Keeling, and Joerg Bohlmann.
MEDIA CONTACT: Joerg Bohlmann, University of British Columbia, Vancouver, CANADA; tel: 604-822-0282; e-mail: < bohlmann@msl.ubc.ca >
Proceedings of the National Academy of Sciences