Abstract
The size and pre-dispersal insect infestation ofQuercus mongolica FiscH. var. grosseserrata REHD. et WILs. acorns were studied from 1991 to 1992 in a naturally-regenerating forest in Hokkaido. Pre-dispersal acorns constantly were infested by Curculio spp. (Curculionidae) or Cydia glandicolana (DANILEVSKY) (Tortricidae), or only rarely by Cydia danilevskyi (KUZNETZOV) (Tortricidae) or an unidentified species of Blastobasidae. Acorn lengths were not different consistently between intact acorns and those infested by Curculio spp. or C. glandicolana, but the mortality of the acorns infested by these insects depended on acorn size. The percentage of acorns with an intact hypocotyl increased as the acorn length increased. In acorns longer than 18 mm, 30 to 38% of those infested by Curculio spp. and 13 to 22% of those infested by C. glandicolana had intact hypocotyls. The number of emerged larvae constantly was single in C. glandicolana, whereas it varied from one to seven, limited by acorn size, in Curculio spp.
