The Mediterranean pine engraver, Orthotomicus (Ips) erosus (Wollaston) (Coleoptera: Scolytidae), was first detected in May 2004 in North America in the central valley of California. Orthotomicus erosus is a pest of pines in the Mediterranean region, South Africa, and Chile and may also vector pathogenic fungi. In California, O. erosus has been found to naturally colonize and develop in Monterey, aleppo, brutia, Canary Island, Scots and Italian stone pine. In the laboratory we tested the reproductive ability of O. erosus in native pines (ponderosa, jeffrey, sugar, lodgepole, Monterey, jack, red, white, loblolly), exotic pines (Canary island, Aleppo, Scots), and non-pine hosts (Douglas-fir, white fir, incense cedar, white spruce, black spruce, tamarack).

To develop a monitoring bait for O. erosus, we tested various semiochemicals. In experiment 1, racemic ipsidienol and 2-methyl-3-buten-2-ol (MB) were not attractive alone but highly attractive combined together. In experiment 2, a low (0.5 – 1.8 mg/d) to medium (17-60 mg/d) release rate of MB in the presence of racemic ipsdienol elicited the greatest response. In experiment 3, O. erosus responded similarly to low to high release rates (0.11- 5.6 mg/d) of racemic ipsdienol when combined to MB. In experiment 4, O. erosus was highly attracted to a bait with (-)-ipsdienol, while (+)-ipsdienol was interrupting flight response. Experiment 5 confirmed that both MB and (-)-ipsdienol were not attractive alone but attractive synergistically. Experiment 6 showed that the presence of á-pinene of any enantiomeric form appeared to enhance attraction when combined with MB and (-)-ipsdienol.