GREENBUG (HOMOPTERA, APHIDIDAE) BIOTYPE SURVEYS IN OKLAHOMA, 1991-1996

Surveys were conducted to determine biotypes of the greenbug, Schizaph is graminum (Rondani), in Oklahoma wheat and sorghum fields in 1991 an d 1992 and again in 1995 and 1996. Biotypes B, C, F and G were present in wheat fields surveyed in March 1991, but 87% of the greenbugs were biotype E. Tn 1992, biotype I was detected in survey samples, but 88% of the greenbugs were biotype E. During the summer of 1995 greenbugs collected in sorghum fields in the panhandle counties of Oklahoma were 58% biotype I, but only 32% biotype I in the southwestern Oklahoma co unties sampled. In the spring of 1996, only 29% of greenbugs from whea t fields in 35 counties were biotype I. Field sampling and laboratory techniques for identifying greenbug biotypes are discussed.