Abstract
An olfactometer was developed to analyze the olfactory response of the Japanese horntail, Urocerus japonicus, adult to volatile constituents of trees. The olfactometer consists of T-shaped branched tubes made from polymethyl methacrylate and polyvinyl chloride, and of chambers to place samples. To the evaluate a suitability of the olfactometer, α-pinene was used as a standard attractant, because it was known to attract female horntails in the field. Females were significantly attracted to α-pinene in the olfactometer significantly, supporting that the olfactometer satisfied requirements to analyze an olfactory response of the horntails to volatiles. The assay revealed that volatile constituents from a fresh bolt of Japanese cedar Cryptomeria japonica, which is a host plant of the Japanese horntail, also attracted females. However, males were not attracted to either α-pinene or volatile constituents from the fresh cedar, indicating that olfactory responses to volatiles are different between males and females. These results suggest that the olfactometer developed here is useful for investigating olfactory responses of the horntails to tree volatiles.
