Long-term seasonal polymorphism of the Krasnodar greenbug population for virulence to sorghum varieties carrying different resistance genes

The genetic structure of the Krasnodar population of the greenbug (Schizaphis graminum Rondani) was analyzed in 2002 to 2010. A high level of general and seasonal polymorphism for the insect virulence to different sorghum accessions was revealed. Abiotic factors were shown to play an important role in the seasonal variation of the frequencies of virulence phenotypes: they can alter the relative competitiveness of greenbug clones, and, therefore, changes in environmental conditions lead to differential selection in the S. graminum population.