Volatile components of Japanese cedar cultivars as repellents related to resistance to Cryptomeria bark borer

Abstract

The response of the essential oils and their components to Cryptomeria bark borer has been studied. The oils of inner bark and sapwood of resistant cultivars acted as a repellent to Cryptomeria bark borer rather than as an attractant, whereas those of susceptible cultivars acted as an attractant. α-Terpineol, nerolidol, δ-cadinene, β-eudesmol, terpinolene, and cedrol showed high repellent activity. The relative contents of the former four compounds were larger in resistant cultivars than in sensitive cultivars. It suggests that these four compounds might be one of the causes of resistance to Cryptomeria bark borer. The contents of terpinolene and cedrol were small, and these two compounds may have no or a small influence on resistance. Although some of compounds acted as attractants for Cryptomeria bark borer, it was not attributable to the difference in the bark borer response of Japanese cedar because of the relatively low ratio of these compounds in each essential oil and the small differences in the ratios between resistant and susceptible cultivars.