DE-NOVO BIOSYNTHESIS OF THE AGGREGATION PHEROMONE COMPONENTS IPSENOL AND IPSDIENOL BY THE PINE BARK BEETLES IPS PARACONFUSUS LANIER AND IPSPINI (SAY) (COLEOPTERA-SCOLYTIDAE)

The California five-spined ips, Ips paraconfusus Lanier, produces the myrcene-derived acyclic monoterpene alcohols ipsenol (2-methyl-6-methy lene-7-octen-4-ol) and ipsdienol (2-methyl-6-methylene-2,7-octadien-4- ol) as components of its aggregation pheromone, The pine engraver beet le, Ips pini (Say), produces only ipsdienol. Previous studies have sho wn that myrcene, a monoterpene in the pines colonized by these beetles , is a direct precursor to these pheromone components, In vivo radiola beling studies reported here showed that male I, paraconfusus incorpor ated [1-C-14]acetate into ipsenol, ipsdienol, and amitinol (trans-2-me thyl-6-methylene-3,7-octadien-2-ol), while male I. pini incorporated [ 1-C-14]acetate into ipsdienol and amitinol, Females of these species p roduced neither labeled nor unlabeled pheromone components. The purifi ed radiolabeled monoterpene alcohols from males were identified by com parison of their HPLC and GC retention times with those of unlabeled s tandards, HPLC-purified fractions containing the individual radiolabel ed components were analyzed by CC-MS and were shown to include only th e pure alcohols, To further confirm that ipsdienol and ipsenol were ra diolabeled, diastereomeric ester derivatives of the isolated alcohols were synthesized and analyzed by HPLC and GC-MS, After derivatization of the radiolabeled alcohols, the HPLC analysis demonstrated expected shifts in retention times with conservation of naturally occurring ste reochemistry, The results provide direct evidence for de novo biosynth esis of ipsenol, ipsdienol and amitinol by bark beetles.