C-1-1

CHARACTERIZATION OF PHEROMONE BIOSYNTHESIS IN BARKBEETLES (COLEOPTERA: SCOLYTIDAE) BY RADIOLABELED IN VITRO SYNTHESIS.

Per Ivarsson1,2, Cari Blomquist1, and Gary J.Blomquist1
1University of Nevada Reno, Mail stop 330, Reno, Nevada89557-0014, USA
2Göteborg University, Chemical Ecology, Carl Skottsbergsgata 22, SE-413 20 Göteborg, Sweden


The two most common aggregation pheromone components for Ips spp.bark beetles are the acyclic monoterpene alcohols ipsdienol and ipsenol.These substances have recently been shown to be synthesized de novo.By using an 14C-acetate in vitro assay with bark beetle tissue,we have demonstrated that plausible precursors are ipsdienone and ipsenone.The production of radiolabeled ketone is enhanced by using enzyme inhibitorsthat direct the synthesis away from alternative routes. The pheromone inIps bark beetles is emitted from the hindgut but our results indicatethat the ketone is synthesized in the thorax of the insect and then transportedto the site of reduction (probably the Malpighian tubules or the gut wall)where the ketone is enantioselective reduced to the alcohol. The synthesisof ketone is under hormonal control, but beside juvenile hormone, otherpossible brain hormones does not seem to be involved.