Reproductive and damage potential of greenbug, Schizaphis graminum, biotypes E, I, and K in the wheat-sorghum cropping system of the central Great Plains

The USDA-ARS Wheat, Peanut and Other Field Crops Laboratory in Stillwater, OK currently  maintains economically important greenbug, schizaphis graminum (Rondani) biotypes and has done so for at least 25 years. These aphids are used for wheat, Triticum aestivum L., barley, Hordeum vulgar L., and grain sorghum, Sorghum bicolor L. (Moench), breeding programs mostly within the United States. There are currently ≈25 identified biotypes that are maintained by keeping them parthenogentic on susceptible barley. Those utilized most frequently in breeding programs and other biological studies are those that pose an economic threat to small grains and grain sorghum, namely B, C, E, F, G, H, I, and K. Of these, biotype E, I and K are considered those encountered in the wheat and sorghum cropping systems of the Central Great Plains. Biotype E has a notorious reputation as a wheat pest that will transition to sorghum. Biotypes I and K are recognized more as sorghum pests that will survive and cause economic damage to wheat. One of our future research objectives is too look at the transition of these greenbug biotypes within the wheat-sorghum cropping system of the Central Great Plains. This will include intrinsic rates of increase studies on wheat and sorghum hosts, preconditioning of the biotypes when reared on one host and used to infest the other, and the temporal abundance and distribution of the differing biotypes in the wheat-sorghum cropping system of the Central Great Plains.