[0704] , The predatory beetle, Trogossita japonica (Coleoptera: Trogossita), feeds on wood boring insects in the forests. The Japanese pine sawyer, Monochamus alternatus, (Coleoptera: Cerambycidae), that transmits the pine wood nematode, Bursaphelenchus xylophilus, the pathogen of the pine wilt disease of Japanese red pines (Pinus densiflora) and black pines (Pinus thunbergii) is one of its prey species. M. alternatus utilizes monoterpenoids, especially alpha–pinene, which are emanated from nematode-infected pine trees, to orientate towards the host trees for oviposition. For T. japonica, it is advantageous to adopt a similar tactic as M. alternatus to locate the oviposition site, since the larvae of T. japonica feeds on the immature stages of M. alternatus in pine forests. We, therefore, analyzed the olfactory response of T. japonica to certain monoterpenoids in an open Y-track olfactometer and also compared the responses between field-collected (experienced) beetles and artificially reared (inexperienced) beetles. Both experienced and inexperienced beetles showed strong responses to alpha-pinene, beta-pinene and a combination of alpha-pinene and EtOH. However, the time taken to locate an odor source by experienced beetles was much shorter than the inexperienced beetles. To delineate the role of pre-exposure to the prey-host tree odor complex by the predator, we further analyzed the responses of the artificially reared beetle, which have had an experience of feeding a prey with pine logs. This had a positive effect on the beetles and the pre-exposure to the pine volatiles certainly enhanced their attraction to the odors. These predators are faster in orienting towards the volatiles, as evident by the lesser time taken to locate an odor source than the inexperienced beetles, thus, demonstrating that the experience modifies the odor location in T. japonica.

Index terms: Terpenoids, Trogossita japonica, pine, predator, alpha-pinene.

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