Antennally mediated negative feedback regulation of pheromone production in the pine engraver beetle, Ips pini
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Bark beetles use monoterpenoid aggregation pheromones to coordinate host colonization and mating. These chemical signals are produced de novo in midgut cells via the mevalonate pathway, and pheromone production may be regulated by a negative feedback system mediated through the antennae. In this study, we explored the effect of antennectomy on pheromone production and transcript levels of key mevalonate pathway genes in juvenile hormone III-treated male pine engraver beetles, Ips pini (Say). Antennectomized males produced significantly greater amounts of pheromone than podectomized males and those with intact antennae. Likewise, mRNA levels of three mevalonate pathway genes important in pheromone biosynthesis were measured by quantitative real-time PCR and found to be induced to a greater extent with antennectomy, suggesting a transcriptional regulation of pheromone production.
KeywordsIps pini Pheromones Antennectomy Juvenile hormone Mevalonate pathway
We thank members of the GJB and CT laboratories for assistance in collecting beetles; the Whittell Forest Management Board, and US Forest Service, South Tahoe District for permission to collect beetle-infested logs; and the Nevada Genomics Center for assistance with qRT-PCR. This work was funded by the USDA-NRI (grant no. 2001-35301-11035) and Nevada Agriculture Experiment Station, publication no. 0339. These experiments comply with the current laws of the USA.
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