REGULATION AND BIOSYNTHESIS OF PHEROMONE COMPONENTS IN THE DOUBLE SPINED BARK BEETLE IPS DUPLICATUS (COLEOPTERA, SCOLYTIDAE)

The double spined bark beetle, Ips duplicatus, uses ipsdienol and E-myrcenol in a 5:1 ratio for its aggregation pheromone (Byers et al., 1990; Schlyter et al., 1992), The biosynthesis and regulation of these pheromone components were studied by using both an enzyme inhibitor, compactin, that blocks the terpene biosynthesis, and a juvenile hormone analogue, methoprene, which stimulates pheromone production, The beetles were also exposed to myrcene, a proposed precursor of the pheromone components, present in the host tree of the beetles, Norway spruce [Picea abies (L.) Karst.]. To study the regulation of pheromone synthesis we used the juvenile hormone analogue, methoprene and Hez-PBAN (Helicoverpa tea pheromone biosynthesis activating neuropeptide). Methoprene (25 mu g/beetle) stimulated pheromone production in the beetles to levels typical for a natural attack on their host tree, This production was accompanied by high levels of 2-phenylethanol, found only in small amounts in wild beetles, We found no evidence that Hez-PBAN stimulates pheromone production in I. duplicatus, neither did it modulate the production of 2-phenylethanol, Both ipsdienol and E-myrcenol were found to be produced de novo and not from myrcene, a hypothesized precursor present in the host tree resin.