Biology of Diastrophus nebulosus (Hymenoptera: Cynipidae) and its parasitoid/inquiline complex in galls on Rubus flagellaris (Rosaceae)

Abstract

Rubus flagellaris patches occasionally harbor colonies of compound stemgalls initiated by the cynipid, Diastrophus nebulosus. These isolated colonies host a parasitoid/inquiline complex made up of five principal and three incidental chalcidoid species and one cynipid inquiline. Over 1-2 seasons, parasitoid/ inquiline infestation reduced primary host populations to lows of 2-0% in some colonies. Despite heavy parasitism in most colonies, dispersal of D. nebulosus out of infested colonies resulted in a survival rate of 22%. Among parasitoids, a new species, Eurytoma rubrigalla, was revealed along with new records for Eupelmella vesicularis and an unidentified Habrocytus species. Immature stages and life histories of D. nebulosus and members of its parasitoid/inquiline complex are illustrated and described with notes on gall genesis and development. Courtship and mating is summarized for Eurytoma diastrophi and arrhenotoky is here first reported for a Nearctic species in Diastrophus.