Nitrogen Fertilizer Influence on Greenbug (Homoptera: Aphididae) Dynamics and Damage to Sorghum1

Abstract
Green bug, Schizaphis graminum (Rondani), densities decreased in direct relationship to nitrogen (N) fertilizer rate (0, 45, 90, 135, 180, and 225 kg N/ha) and to increase in plant dry matter. Damage ratings related to green bug density indicated that N fertilizer did not alter natural sorghum tolerance to greenbugs. Greenbug dynamics responded in a positive manner to NH4+-N content in leaves. These data indicate that increasing N fertilizer enhanced sorghum fitness as a green bug host. However, the rate of aphid increase diminished at the higher N concentrations.