GREENBUG DNA CONTENT

Nuclear DNA content of nymphal, and male and female adult biotype C an d E greenbugs, Schizaphis graminum (Rondani), laboratory-reared or fie ld-collected from sorghum, Sorghum bicolor (L.) Moench, johnsongrass, Sorghum halepense (L.) Pers., and wheat, Triticum aestivum L., was det ermined using flow cytometric DNA analysis. DNA content for all greenb ugs analyzed ranged from 0.91-1.24 pg/cell, with a mean of 1.06 pg/cel l. DNA content of 1- and 7-d-old greenbug nymphs did not differ signif icantly. Biotype E male greenbugs contained more DNA than biotype C ma les, but the level between sexes was not significantly different. DNA content of biotype E greenbugs averaged 1.05 pg/cell while that of bio type C greenbugs was 1.02 pg/cell. Greenbug biotypes reared on sorghum had lower amounts of DNA (0.99, 1.03, and 1.07 pg/cell for biotype C, biotype E, and field-collected biotype E, respectively) than did the same biotypes reared on wheat and johnsongrass. These results suggest that flow cytometric DNA analysis should be further tested as a means of studying aphid genetics and clonal diversity.