ANTHRAQUINONES IN THE LEAF BEETLE TRIRHABDA-GEMINATA (CHRYSOMELIDAE)

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