Temporal dynamics of Otiorhynchus schlaeflini (Coleoptera: Curculionidae) adults and damage assessment on two wine grape cultivars.

The nocturnal temporal dynamics of adults of Otiorhynchus schlaeflini Stierlin on wine grape Vitis vinifelra L. 'Rhoditis' and 'Mavroudi' were studied in the western Peloponnese during spring 1993 and 1994. The maximum number of adults was recorded approximately 3 h after sunset. Emergence began on 13 March 1993 and 19 March 1994; the population peaked on 24 and 16 April in each year, respectively. Low numbers of adults were found during daytime observations in May. The length and the number of knobs, and the number of grapes on twigs from damaged buds were significantly reduced only in 'Rhoditis'. However, the weight of grapes produced on twigs developed from damaged buds was significantly less than those from undamaged buds in both cultivars. We found that the severity of damage caused to buds is dependent on the wine grape cultivar. Therefore, the effect of wine grape cultivar should be taken into account when estimating the economic threshold.