Occurrence of insecticide resistant greenbugs (Homoptera: Aphididae) in Kansas, Texas, Oklahoma, and Colorado and suggestions for management

Polyacrylamide gel electrophoresis was used to resolve esterase isozymes that were related to insecticide resistance in greenbug, Schizaphis graminum (Rondani). This report documents the occurrence of esterase polymorphisms in the Midwest and assesses differences in regional occurrences. In total, 13,863 individual greenbugs from Kansas, Texas, Oklahoma, and Colorado were tested between 1991 and 1995. The occurrence of resistant greenbugs appeared to be greatest in the southwest crop reporting district of Kansas and the north plains crop reporting district of Texas. The overall incidence of pattern 1 resistant greenbugs declined from 7.1% in 1991 to 1% in 1994 and 1995. Pattern 2 resistant greenbug occurrence varied from year to year (5.7-29.8%). Several explanations for the spatial occurrence of resistant greenbugs and several techniques for managing resistant greenbug populations are offered