Journal of Economic Entomology · 1983 · 39 citations · 0 references
During the winter of 1979–1980, a new biotype of the greenbug, biotype E, was reported. The reactions of various host plants to this greenbug were tested by measuring one or more of the mechanisms of host plant resistance. In our tests, we showed that the resistant wheats, ‘Amigo’ and ‘Amigo/Payne,’ did not possess the antibiosis and tolerance previously experienced with biotype C, but retained their antixenosis, as did ‘Gaucho,’ a triticale from which Amigo was developed. ‘Largo’ appeared as resistant to E as it was previously to C. Testing ‘Insave F.A.’ rye suggested that more than one gene for resistance was involved, but unfortunately the one gene effective for biotype E was not transferred to Amigo. Oats seemed to be little affected by the biotype change. The new biotype E was able to injure previously resistant sources of feed barley, although some antibiosis still is effective. Commercial grain sorghum lines, previously resistant to greenbug, are now susceptible, but ‘P1220248,’ ‘P1264453,‘ and ‘Capbam’ indicate a useable level of resistance to biotype E. Bloomless (bm bm) appeared to maintain its resistance, and was effective against biotype E. In general, the occurrence of the new biotype has affected many of the previous resistant genotypes that had been developed in small grains and sorghum.