Chemistry of Leichhardt's Grasshopper, Petasida ephippigera, and its Host Plants, Pityrodia jamesii, P. ternifolia, and P. pungens

Investigation of the strikingly aposematic Leichhardt's grasshopper revealed a number of host-plant-derived components. Chemical study of the three known host plants revealed a diverse array of components. Pityrodia ternifolia and P. pungens contain predominantly sesquiterpenes and sesquiterpene glycosides and P. jamesii is rich in cineole, dihydrochalcones, chalcones, and monoterpene glycosides. Feces from grasshoppers feeding on P. jamesii contain a mixture of hydroxycineoles, of which 3-hydroxycineole is the predominant isomer (68%). No evidence for previously suspected "alkaloidal" toxins was found in either the insect or host plant.     

Metabolism of 1,8-cineole in tea tree (Melaleuca alternifolia andM. linariifolia) by pyrgo beetle (Paropsisterna tigrina)

The frass of the pyrgo beetle (Paropsisterna tigrina) feeding on commercial plantations of the terpinen-4-ol chemical variety of the Australian tea tree.Melaleuca alternifolia, was found to contain a volatile oil almost identical to the essential oil of the ingested leaf. When beetles were fed leaf containing substantial quantities of 1,8-cineole, the predominant frass metabolite as determined by MS, IR,¹³C and¹H NMR, GC, and CoGC was (+)-2-hydroxycineole. Both male and female adults and larvae metabolizedMelaleuca oils in similar ways.