Insect predation and seasonal seedfall of the Japanese beech, <i>Fagus crenata</i> Blume, in northern Japan

Abstract

Abstract The relationship between seasonal changes in seedfall pattern of the Japanese beech, Fagus crenata , and insect damage to the trees is discussed. Twenty‐six lepidopteran species and one dipteran species were found during a 7‐year study. Insect damage was classified into two categories: feeding by seed insects and feeding by foliage insects. The latter was speculated to occur by chance. Twenty‐three lepidopteran species were identified as foliage feeders and, except for Venusia phasma , their densities were small. There were four seed insects: three Lepidoptera and one Diptera. Because Pseudopammene fagivora was the most abundant in all study plots, this seemed to be the most important insect species related to the seed survival of the Japanese beech. Insect damage was observed early in the season from the time of flowering until mid‐June, except that by two seed insects, P. fagivora and an unidentified lepidopteran of the family Gelechiidae. Most of the seeds infested by insects fell by the end of July. Seedfall throughout the season should be investigated in order to fully understand the interaction between seed production and insect infestation.