Yield-Loss Relationships and Economic Injury Levels for European Corn Borer (Lepidoptera: Pyralidae) Populations Infesting Pennsylvania Field Corn

Abstract

Field studies were conducted during 1986 and 1987 to quantify the relationship between the number of European corn borer, Ostrinia nubilalis (Hubner), larvae per corn plant, plant growth stage, and corn grain yield for Pennsylvania. Corn plants were artificially infested with third-instar O. nubilalis during four plant stages (10-leaf, 16-leaf, blister, and dough) with 0, 2, 4, or 6 larvae per plant. Differences in grain weights between the uninfested check plots and highest infestation levels for 10-leaf, 16-leaf, blister, and dough stages of corn development in 1986 were 63.84, 69.07, 47.09, and 13.17 g per plant, respectively. In 1987, corn grain weights were reduced at six larvae per plant from the check by 50.57, 33.73, 22.9, and 2.79 g per plant for 10-leaf, 16-leaf, blister, and dough stages of corn development, respectively. Based on the linear regressions of the relationship between number of larvae per plant and corn grain weight for all four corn growth stages by year, average grain weight reductions across years when stalk feeding was initiated during the 10-leaf, 16-leaf, blister, and dough stages of plant development were 5.94, 5.01, 3.13, and 2.41% per larva per plant, respectively. Economic injury levels are presented for cases in which 100% control of O. nubilalis populations is assumed, and a method is shown for calculating economic injury level values when less than 100% control is expected.