A collection of greenbugs, Schizaphis graminum (Ron-dani) (C-biotype), from a population causing extensive damage to sorghum, differed from green bugs (B-biotype) originating on wheat. ‘Piper’ Sudan grass, Sorghum Sudanese (Piper) Staff., in the seedling stage was highly resistant to the B-biotype and susceptible to the C-biotype. Differences in green bug reaction or plant injury caused by the 2 biotypes were recorded also for wheat, Triticum aestivum L.; rye, Secale cereale L.; oats, Avena sativa L.; barley, Hordeum vulgare L.; and sorghum Sorghum bicolor (L) Moench. With few exceptions, survival rates of nymphs of the 2 biotypes were similar on 30 species of Gramineae.
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Harvey et al. (1969) studied this question.