Influence of previous frost damage on tree growth and insect herbivory of Eucalyptus globulus globulus

The plant stress hypothesis suggests that some herbivores favour stressed p lants, whereas the plant vigour hypothesis proposes that other herbivores p refer vigorous plants. The effects of a prior stress, that of frost damage, were examined on the subsequent growth of Eucalyptus globulus globulus and on the response of insect herbivores. Frost damage affected tree growth by reducing new leaf area and increasing specific leaf area (SLA). However, h erbivore abundance was not affected by prior frost damage. Two feeding tria ls using Anoplognathus chloropyrus and Hyalarcta huebneri and a morphometri c study of Ctenarytaina eucalypti were conducted to assess the performance of herbivores on trees that had suffered more or less frost damage. Consump tion by A. chloropyrus and H. huebneri was unaffected by foliage origin (da maged versus healthy). Hyalarcta huebneri grew faster when fed leaves from previously damaged trees, and C. eucalypti from previously damaged trees we re larger than those from healthy trees. Enhanced insect performance on fro st damaged plants may have resulted from the high specific leaf area (most likely thinner) leaves. The herbivore abundance data did not support the hy pothesis that previously frost damaged plants are preferred by insects. How ever, increased growth of H. huebneri and larger body size of C. eucalypti on damaged trees indicates that previously stressed trees may produce leave s of higher nutritional value.