Ultrastructure of galls produced on Solidago altissima L. by Eurosta solidaginis (Fitch) with emphasis on the nutritive and cortical tissues
Bross, Lori Seegers
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Larvae of Eurosta solidaginis induce spheroid galls upon Solidago altissima as a means of protection and to obtain food. Transmission electron microscopy was used to examine three facets of gall development: (1) the changes which take place within the gall tissue over time, (2) features of the nutritive tissue which enable it to sustain the developing larva, and (3) the origin of gall tissues, especially with regard to replacement of consumed nutritive tissue cells. Nutritive tissue cells were cytoplasmically rich and metabolically active, as evidenced by the presence of numerous lipid droplets, rough endoplasmic reticulum, and especially in older galls, chloroplasts containing protein bodies. Cortical cells exhibited a limited amount of peripheral cytoplasm and also contained relatively large amounts of electron-dense globules, believed to be latex. Degenerating chloroplasts were present in both tissues. Dividing cells were often observed in b meristematic layer Just outside the nutritive zone. This layer might be responsible for replacing the nutritive cells as they are consumed by the larva. The possible role of wound response and/or chemical stimulation in gall formation is discussed.