DEMONSTRATION OF DE-NOVO PHEROMONE BIOSYNTHESIS IN IPS-DUPLICATUS (COLEOPTERA, SCOLYTIDAE) - INHIBITION OF IPSDIENOL AND E-MYRCENOL PRODUCTION BY COMPACTIN

The biosynthesis of ipsdienol and E-myrcenol was studied in the bark b eetle Ips duplicatus by using the enzyme inhibitor compactin. The inhi bitor specifically blocks the action of the enzyme hydroxymethylglutar yl-coenzyme A reductase, that operates early in terpene biosynthesis p rior to the formation of mevalonate. Compactin was injected in the bee tle's abdomen using a thin tapered glass needle; controls were injecte d with saline blank. The release of ipsdienol and E-myrcenol was reduc ed by 70 and 40% respectively in I. duplicatus beetles injected with c ompactin over a period of 17-25 h after injection. Thus, ipsdienol and E-myrcenol can be synthesized de novo and not only by the hydroxylati on of exogenous myrcene, from the resin of the attacked host trees. To test the possibility that the inhibitor causes a non-specific metabol ic depression of the beetles, I. typographus was subjected similarly a nd monitored for the hydroxylation of (-)-alpha-pinene, forming cis-ve rbenol. The production of cis-verbenol is not affected by compactin.