| Abstract | The population density of Closterotomus trivialis (Costa) and its damage potential were studied in citrus and olive orchards of Crete. C. trivialis was found to be most abundant in wild radish Raphanus raphanistrum L., annual mercury Mercurialis annua L., Urtica sp. and upright pellitory Parietaria officinalis L. compared to mallow Malva sylvestris L., prickly goldenfleece Uropermum picroides (L.), sowthistle Sonchus oleraceus L., citrus or olive trees. Its damage potential on the setting of olive fruit was investigated at the early inflorescence stage. When 1, 5 or 10 adults of C. trivialis were enclosed with stems at the 55th and 57th phenological growth stages, the number of fruits was significantly reduced compared to controls.
The developmental biology of individuals of C. trivialis was studied on R. raphanistrum at seven constant temperatures 15, 20, 25, 30, 32.5, 35 and 37 °C, under laboratory conditions. No nymphs survived above 35 °C. The highest nymph to adult survival (89.6%) was found at 20 °C and the lowest (40.6%) at 32.5 °C. Mean developmental time as well as adult longevity decreased with increasing temperature. The developmental time from 1st nymphal instar to adult ranged from at least 9.0 at 32.5 °C to 27.8 days at 15 °C. The adults lived from 2.9 days at 32.5 °C to 45.3 days at 15 °C. It required 212.7 degree-days to complete development above a minimum threshold of 7.72 °C as estimated by linear regression and 8 °C as estimated by nonlinear model. The importance of these findings in the management of this species through the prediction of its seasonal appearance is discussed. |
