Mj. Steinbauer et al., COMPARISON OF DAMAGE TO EUCALYPTUS CAUSED BY AMORBUS-OBSCURICORNIS AND GELONUS-TASMANICUS, Entomologia experimentalis et applicata, 82(2), 1997, pp. 175-180
Amorbus obscuricornis (Westwood) and Gelonus tasmanicus (Le Guillou) (
Heteroptera: Coreidae) are specific to Eucalyptus (Myrtaceae). A. obsc
uricornis feeds almost exclusively upon apical shoots and causes a cha
racteristic wilting and necrosis. By comparison, the feeding activitie
s of G. tasmanicus result in no obvious phytotoxicosis. Salivary gland
extracts from both species exhibited sucrase activity but no pectinme
thylesterase (PME) activity. Saliva from A. obscuricornis also exhibit
ed considerable oxidase activity. Sucrase activity was significantly h
igher in extracts derived from C. tasmanicus than from A. obscuricorni
s, but this could not explain the observed differences in phytotoxic s
ymptoms. It is suggested that differences in plant damage are attribut
able to the site of feeding activity (i.e. young versus mature tissue)
, which predetermines the reactivity of host tissues, and/or the quant
ity of salivary enzymes injected.