Anthraquinones in the leaf beetle trirhabda geminata (Chrysomelidae)

Abstract

Hydroxylated anthraquinones have been found to accumulate in different developmental stages of the chrysomelid beetle Trirhabda geminata. Eggs, larvae and adults were analyzed by HPLC and GC-MS. Each developmental stage analyzed contained 1,8-dihydroxy-3-methyl-anthraquinone (chrysophanol) and 1,8-dihydroxyanthraquinone (chrysazin). No anthraquinones were detected in the faeces of T. geminata. The level of stored anthraquinones did not change during starvation. In the host plant of this specialist herbivore, the brittlebush Encelia farinosa (Asteraceae), anthraquinones were not detected. Possible biological functions of anthraquinones stored in T. geminata are discussed.