Antifeeding Active Substances for Insect in Caryopteris divaricata Maxim.

Six antifeeding active diterpenes having a clerodane skeleton, clerodin (I), caryoptin (II), dihydroc?erodin-I (V), dihydrocaryoptin (VI), clerodin hemiacetal (VII), and caryoptin hemi- acetal (VIII), were isolated from Caryopteris divaricata Maxim. Antifeeding activities of six compounds and these derivatives against the 3rd instar larvae of Spodoptera litura F. were tested by the leaf disk method. In addition, the terms of “relative antifeedant” and “absolute antifeedant” were proposed for the antifeeding substances, and the latter term was used to the above six diterpenes.