| Diplolepis spinosa Ashmead (Hymenoptera: Cynipidae) induces polythalamous (multi-chambered) galls on the stems of Rosa blanda Ait. throughout central and northern Ontario, as well as on introduced domestic roses within and near urban centres. The most significant mortality factor for the inducers in this gall is a group of hymenopteran parasitoids that feed on the larvae during the summer of gall induction. Diplolepis spinosa larvae are attacked as well by cynipid inquilines of the genus Periclistus Forster. Mature galls of D. spinosa were harvested in the early spring in the year following induction and returned to the laboratory to emerge the inducers, parasitoids and inquilines.;Galls were harvested over two geographic clines in northern Ontario, one in eastern Ontario from Manitoulin Island to Moose Factory Island and the other in western Ontario from Rainy River to Red Lake.;An experimental plot was established at an urban site within the city of Sudbury, Ontario to study the establishment of parasitoids in a new population of galls and to examine the influence of the species of host plant on the composition of component communities associated with galls. (Abstract shortened by UMI.). |
