| Diplolepis triforma Shorthouse and Ritchie (Hymenoptera: Cynipidae) induce fusiform, multichambered, prosoplasmic galls in the stem tissue of Rosa acicularis Lindl. (Rosaceae). The population found at a field site near Sudbury ON was attacked by two species of parasitoid Hymenoptera: Eurytoma sp. Illiger (Eurytomidae) and Glyphomerus stigma Fabricius (Torymidae), both of which feed on insect and plant tissues.; Galls of D. triforma undergo three phases of development: initiation, growth, and maturation. Initiation begins with the deposition of several eggs (mean = 7) into buds of R. acicularis. The ovipositor cuts through immature epidermis and cortex to place the distal pole of each egg in contact with the procambium and immature pith. Gall formation begins before the eggs hatch. Once hatched, larvae begin to feed before fully emerging from the egg, forming a spherical chamber which they subsequently occupy. Cells lining the larval chamber differentiate into nutritive cells, which serve as food. (Abstract shortened by UMI.)... |
