Effect of soybean resistance on soybean aphid (Aphis glycines Matsumura) biotypes

The soybean aphid, Aphis glycines Matsumura, is an exotic pest, and causes millions of dollars in losses to soybean crop. Development of resistant varieties is one of the important control methods to this insect pest. In this study, we used three soybean aphid biotypes (biotype 1, 2 and 3) for the experiments with different soybean genotypes. Here, different screening and characterization studies are included to categorize and quantify soybean resistance. The results showed that the soybean genotypes varied in their resistance and susceptibility with three aphid biotypes, with biotype 1 found to be less virulent than the other two biotypes in most of the genotypes. But surprisingly, some genotypes those were earlier found resistance to biotype 1 and susceptible to biotype 2, showed a revival in resistance with biotype 3. Characterization and chlorophyll loss studies found significant differences between resistant and susceptible genotypes with these biotypes. Also the categories of resistance varies with biotypes in different soybean genotypes.