Isolation of 8-hydroxygeraniol-8-O-beta-D-glucoside, a probable intermediate in biosynthesis of iridoid monoterpenes, from defensive secretions of Plagiodera versicolora and Gastrophysa viridula (Coleoptera: Chrysomelidae)

8-Hydroxygeraniol and its 8-O-beta-D-glucoside have been found as trace components in the defensive secretions of Plagiodera versicolora and Gastrophysa viridula larvae. This discovery supports the hypothesis that the evolution of the utilization of plant precursors by some chrysomelid species was favored by the plesiomorphic occurrence of a beta-glucosidase and an oxidase in the defensive secretion of iridoid-producing species.