Adaptations of Gall Wasps of the Genusdiplolepis(hymenoptera: Cynipidae) and the Role of Gall Anatomy in Cynipid Systematics

Adaptations and attributes of gall-inducing cynipid wasps are reviewed to emphasize that differences in life cycles and anatomical features of their galls are just as useful for systematic purposes as are structural differences in the adult insects themselves. The extent to which cynipid wasps have specialized is illustrated by the genusDiplolepis, all species of which are restricted to native and introduced roses and induce structurally distinct galls. Various aspects ofDiplolepisbiology including life cycles, host specificity, and gall development and anatomy are reviewed. The biologies of two species ofDiplolepisthat commonly co-exist in the same habitat in central Ontario are then examined in detail.Diplolepis polita(Ashmead) induces a single-chambered gall on the leaves ofRosa acicularisLindl. whereasDiplolepis spinosa(Ashmead) induces a multi-chambered gall on the stems ofRosa blandaAit. Differences in life cycles, distribution, host and organ specificity, oviposition, gall initiation and development, along with differences in the communities of parasitoids and inquilines attracted to the galls, confirm the existence of distinct species and allow some speculation on their ecological and phylogenetic relationships.