Response of Wheat Seedlings to Actual and Simulated Migratory Grasshopper Defoliation1

Regrowth of wheat seedlings subjected to equal levels of actual insect defoliation (grasshopper grazing) and simulated insect defoliation (manual clipping) was compared. Severe defoliation by Melanoplus sanguinipes (F.) resulted in a significantly lower rate of seedling regrowth as compared to an equal level of manual clipping. Also, plant response to type of defoliation varied significantly with degree of defoliation. These results suggest that defoliation by chewing insects may be more difficult to simulate than is generally acknowledged.