Patterns of Insect Predation on Seeds of Smooth Sumac (Rhus glabra L.)

Morphological and spatial characteristics of nine female clones of smooth sumac were measured to see if they influenced intensity of predispersal seed predation by a chalcid wasp (Eurytoma seminis, Hymenoptera). X-ray radiography was used to inspect seeds. Seed viability for the clones ranged from 0-25.3%o (only two clones had viability rates above 1%To). Chalcid wasps destroyed from 37.3-83.3%To of the seeds in these clones. Predation rates were higher in clones adjacent to other clones and in clones with larger infructescences. Stem and fruit characteristics affected predation levels within clones, but the relationships differed among clones. Sumac clones in this area may have become more vulnerable to seed predators recently due to sumac's abundance and the suppression of fires.