Abstract
The relationship between the density of S. dorsalis on satsuma mandarin fruit and damage at harvest was analyzed from investigations in 12 mandarin groves in Shimizu, Shizuoka Prefecture during 1984-1988. Damage to the pedicel of fruits started to appear in early June and was maximum in early August. Silver-scar damage to the stylar end of fruits appeared from mid-August and was maximum at mid-September. Based on regression analysis of the damage to larval density, damage to the pedicel at harvest is related to the maximum larval density during the infestation period. However, no relationship was detected between damage to the stylar end and maximum larval density. The economic threshold for the fruit pedicel was calculated to be 8.0% expressed as a ratio of sampled fruits in which the larvae were found from early June to late July. The larvae were more aggregated than the adults within a tree and between trees.
