Distribution of European Corn Borer (Lepidoptera: Pyralidae) Egg Masses and Larvae on Sweet Corn in New York

Abstract

Studies were conducted in commercial sweet corn fields in upstate New York to collect information for developing a sampling protocol for egg masses and larvae of European corn borer (ECB), Ostrinia nubilalis (Hubner). Information was collected on 1) aggregation of populations in portions of the field (e.g., aggregation along borders), 2) distribution of sample observations for a whole-plant sample unit, and 3) distribution of insects within the sample unit (i.e., the within-plant distribution of eggs and larvae). Analyses of data indicated that distribution of egg masses and larvae throughout a field was essentially random with no evidence to support the hypothesis that eggs were preferentially laid near field borders where mating and resting of female adults occurred. From data on dispersion of ECB on individual plants, a Poisson series is a reasonable model for characterizing distribution of ECB egg masses. Parameters of a variance-mean model for the small larvae indicate that these larvae are highly aggregated but that aggregation becomes less pronounced as larvae mature. Since control measures are most effective against egg masses and small larvae, a sampling protocol that utilizes characteristics of both stages should be employed. An index of ovipositional activity measured via incidence of egg masses on plants can be determined by inspecting plants for presence of either egg masses or small larvae. This can be accomplished by using a binomial-based sequential sampling plan.