Effects of gall formation by <i>Dryocosmus kuriphilus</i> Yasumatsu (Hym., Cynipidae) on the growth of chestnut trees

Abstract

Abstract Effects of gall formation by Dryocosmus kuriphilus on the growth of the Japanese chestnut tree (Castanea crenaia) were investigated from 1988 to 1989 using 15 wild trees. Mean leaf area on galled shoots currently expanded was about a half that on ungalled shoots. Galled shoots were lower than ungalled shoots both in biomass ratio of leaf/shoot and in mean number of winter buds per shoot. Bud expansion on galled shoots was less successful. Total biomass of current shoots diminished under heavy infestation with D. kuriphilus. Thus, D. kuriphilus not only retarded the development of photosynthetic organs but also reduced the biomass production of host trees in the next year. This may be a causal mechanism of biomass decline in gall‐infested trees.