EVIDENCE FOR ABSORPOTION OF EUCALYPT ESSENTIAL OILS BY PAROPSZS ATOMARZA OLIVIER (COLEOPTERA. CHRYSOMELIDAE)

Abstract A terpenoid budget was constructed for Paropsis atomariu (Olivier) feeding on Eucalyptus blakelyi Maiden leaves to determine if larvae absorbed leaf terpenoids. Groups of larvae were fed leaves which contained a range of terpenoid concentrations (1–7.9%). The amounts of terpenoids consumed and excreted by each group were determined. Calculation of the ‘expected’ concentration of terpenoids in the excreta was calculated based on the digestive efficiency of each larval group and the assumption that terpenoids passed unaffected through the digestive system. Comparisons of the amounts of terpenoids excreted with amounts expected if no absorption occurred showed that larvae absorbed a major proportion of ingested terpenoids. Larvae absorbed, or otherwise converted to other compounds, 86% of ingested cineole, a component which commonly makes up more than 75% of the total terpenoids in E. blakelyi. Analyses of larval tissue showed that leaf terpenoids were not present and therefore not sequestered. It is suggested that larvae metabolise leaf terpenoids.