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Developmental morphology of stem galls of Diplolepis nodulosa (Hymenoptera: Cynipidae) and those modified by the inquiline Periclistus pirata (Hymenoptera: Cynipidae) on Rosa blanda (Rosaceae)

1998; Canadian Science Publishing; Volume: 76; Issue: 3 Linguagem: Inglês

10.1139/b98-001

1480-3305

Scott E. Brooks, Joseph D. Shorthouse,

Forest Insect Ecology and Management

Diplolepis nodulosa (Beutenmüller) induces small, single-chambered, prosoplasmic galls in stems of Rosa blanda Ait. Gall initiation begins when adult females deposit a single egg into the procambium of R. blanda buds. Pith cells at the distal pole of the egg lyse forming a chamber into which the hatching larva enters. Cells lining the chamber differentiate into nutritive cells, which serve as the larval food. Gall growth is characterized by the proliferation of parenchymatous nutritive cells causing gall enlargement. A separate gall vasculature does not form, but instead, gall tissues are irrigated by the existing stem vasculature. Maturation begins when gall tissues cease proliferating and differentiate into distinct layers concentrically arranged around the larval chamber. The innermost layer is composed of cytoplasmically dense nutritive tissue, followed by parenchymatous nutritive tissue, sclerenchyma, cortex, and epidermis. Parenchymatous nutritive tissue differentiates into nutritive tissue and is consumed by the larva. Galls of D. nodulosa are susceptible to anatomical modification by the phytophagous inquiline Periclistus pirata (Osten Sacken). Galls attacked by P. pirata become enlarged and multichambered, with little resemblance to inducer-inhabited galls. Periclistus pirata kill the larva of D. nodulosa at oviposition and deposit several eggs per host gall. Inquiline-occupied galls may contain the eggs of several females. Nutritive tissue induced by D. nodulosa disintegrates. Growth of attacked galls occurs prior to hatching of P. pirata eggs. At egg hatch, the gall appears as an enlarged hollow sphere and larvae disperse over the chamber surface and feed on parenchymatous tissue. Feeding induces tissue proliferation, which surrounds each larva within its own chamber. As galls mature, cells surrounding each larval chamber lignify forming a sclerenchyma sheath. Cells inside the sclerenchyma sheath differentiate into nutritive cells and are consumed by the inquiline larvae.Key words: Rosa, Cynipidae, gall, developmental morphology, inquiline.