Chestnut Gall Wasp, Dryocosmus kuriphilus YASUMATSU (Hymenoptera : Cynipidae) : Analyses of Records on Cell Contents inside Galls and on Emergence of Wasps and Parasitoids outside Galls

Abstract

There was a similarity between the annual trends in the development of Dryocosmus kuriphilus within galls and the emergence of adults out of the galls. The time of 50% emergence of adults fluctuated in proportion to the extent of the thermal deviation from an ordinary year. The percentage of parasitism increased both for the whole parasitoid species and for Torymus beneficus and T. sinensis at the Fruit Tree Research Station in 1984, presumably due to the increased activity of T. sinensis, which had been released there in 1982. Among the parasitoids other than the above-mentioned two species, Megastigmus nipponicus, Ormyrus flavitibialis and Eurytoma brunniventris were predominant. Mortality of adult Dryocosmus due to failure of abandoning the galls was considerably high every year.