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The relationship of the β-myrcene content with the susceptibility and/or resistance of Pinus species against the pine wood nematode was investigated. For this purpose, the β-myrcene content of the wood of one-year-old shoots was determined. The resistant trees were found to contain a very small amount of β-myrcene. On the other hand, the β-myrcene content of susceptible trees was comparatively high. This relationship was observed in both inter- and intraspecies and also between young and older trees of the same species, i.e., Pinus densiflora or P. thunbergii. The β-myrcene content can feasibly be used as an indicator for screening resistant Japanese red and black pine trees.

A new convenient assay method for nematode attractants was developed. Using this method, the attracting activity of volatile components in a pine, Pinus densiflora, was examined for the pine wood nematode, Bur saphelenchus xylophilus, which causes serious damage to pine trees in Japan. Among the volatile components, β-myrcene showed the strongest attracting potency. This compound was assumed to play an important role in the transmigration of the nematode from the sawyer to the pine tree and for the movement of the nematode inside the pine wood.