Technical Abstract: Future advances in wheat (Triticum aestivum L.) and sorghum (Sorghum bicolor L.) resistance to greenbug (Schizaphis graminum L.) will likely come from the introduction of single transgenes that impart antibiosis traits to the host plant. This approach to pest management is incompatible with the time-honored interpretations of simulation models which imply that tthe deployment of single genes that impart antibiosis properties drives th development of new, virulent greenbug biotypes. To understand the relationship between the deployment of resistance genes and the development of new greenbug biotypes we examined the history of greenbug resistance efforts in wheat and sorghum and the corresponding impact these efforts had on the development of new biotypes. We concluded from this analysis that there was absolutely no relationship between the deployment of single, antibiosis genes in wheat and the development of new greenbug biotypes. For rsorghum, only in the case of two of the eleven biotypes can there arguably be any linkage between the release of resistant sorghum hybrids and the development of new biotypes. Even in these two cases there were no clear cause-and-effect relationships established. We suggest that possible effects on aphid population genetics not be considered an obstacle when deploying insect resistance genes.