Economic Injury Levels for Sorghum Midge, Stenodiplosis sorghicola1,and Corn Earworm, Helicoverpa zea2, Feeding on Panicles of Sorghum, Sorghum bicolor

Abstract

Abstract Sorghum midge, Stenodiplosis sorghicola (Coquillett), and corn earworm, Helicoverpa zea (Boddie) are important insect pests of sorghum, Sorghum bicolor (L) Moench. Both pests feed on the developing kernel and directly reduce grain yield. Economic injury levels (EIL) that respond to pest management costs, commodity values and pest density are developed for each pest based upon published reports on grain loss per insect stage and stage-specific mortality. The economic injury level for sorghum midge is M = C 33,256 / V F where M = mean number of adult sorghum midge per flowering panicle, C = cost of management to control sorghum midge per unit area ($/acre), V = market value per unit of production ($ per 100 lbs of sorghum grain), and F = number of flowering panicles per acre. The EIL for sorghum midge is expressed as the number of adult sorghum midge per flowering panicle because only flowering panicles are susceptible to oviposition by sorghum midge females. Corn earworm larval stage must be consi...