Abstract
Insects attacking acorns of 4 deciduous oaks, Quercus serrata, Q. aliena, Q. acutissima, and Q. variabilis, at the same site were investigated. Seasonal changes in acorns dispersed, insect fauna on pre-dispersal acorns, and the damage rate by each insect on pre-dispersal acorns differed between Section Prinus (Q. serrata and Q. aliena) and Section Cerris (Q. acutissima and Q. variabilis), but were similar between species in the same section. Total number of acorns of Section Prinus was larger than that of Section Cerris, but the biomass of acorns was not different between sections. Trees of Section Prinus dispersed a lot of acorns with discolored cotyledons (most of them might have been aborted acorns) and immature acorns absorbed by weevils. In particular, Q. serrata dispersed the largest number of absorbed acorns among 4 tree species, and as Q. variabilis dispersed the smallest number. Thus, Q. serrata, which dispersed the largest number of acorns among 4 oak species, dispersed the smallest biomass of uninjured acorns, but Q. variabilis, which dispersed the smallest number, dispersed the largest biomass without injury. Insect damage to post-dispersal acorns was similar for all oak species.
