Developmental morphology of galls induced by Diplolepis rosaefolii (Hymenoptera: Cynipidae) on the leaves of Rosa virginiana and the influence of Periclistus species on the D. rosaefolii galls

The larval stages of the cynipid wasp Diplolepis rosaefolii induce the formation of single-chambered lenticular galls on the leaves of the wild shrub rose, Rosa virginiana. The gall consists of four tissue layers which surround a centrally located larval chamber. These include an outermost dermal layer, underlying parenchyma, sclerenchyma, and nutritive tissue.

Development in the D. rosaefolii galls involves a number of characteristics which are unique to this gall, and differ markedly from development in other Diplolepis galls studies. These characteristics include the presence of double sclerenchymal layers and the lack of vascularization in the gall wall. Periclistus is an inquiline in the galls induced by D. rosaefolii. Under the influence of Periclistus larvae, a number of morphological changes, including an increase in the number of larval chambers, were observed in the galls. Initially, a loss of D. rosaefolii-induced nutritive tissue is seen when Periclistus eggs are laid in the galls. Once the Periclistus larvae hatch, the number of cells which make up the parenchyma increases. Changes in tissue type, proportion, and overall morphology exhibited by Periclistus-modified galls were studied using conventional light microscopy techniques.