Using a decision model to optimize european corn borer (Lepidoptera: Pyralidae) egg-mass sampling

Egg-mass dispersion patterns of second-generation European corn borer (ECB), Ostrinia nubilalis (Hubner), were determined for 60 cornfields sampled in Shawnee County, Kans., during 1982 and 1983. Among those fields, egg masses appeared to be randomly dispersed in 53 fields. Sample number curves were developed for five-plant samples of egg masses at four precision levels, and number of samples required to adequately sample a cornfield at 8 and 32% completion of oviposition was determined. Results indicated that sampling entire corn plants was logistically and economically unfeasible; use of partial plant samples was evaluated using economic analysis techniques. Using an ECB decision model, cost of increased predictive error was determined for corrected, reduced leaf counts. Total cost associated with egg-mass sampling was determined by summing predictive (decision) error cost and sampling cost. Optimal number of leaves to sample under three economic conditions was determined by locating the number of leaves that resulted in minimum total cost.