Spatial Distribution of Adult Corn Flea Beetles, Chaetocnema pulicaria (Coleoptera: Chrysomelidae), in Sweet Corn and Development of a Sampling Plan

Abstract

The com flea beetle, Chaetocnenw pulicaria Melsheimer, is an important pest of sweet com because it transmits Erwinia stewartii (Smith) Dye, the causal pathogen of Stewart’s wilt. Our goal was to quantify corn flea beetle distribution within and between sweet com plants and develop a sampling method that would be compatible with an existing sampling plan for lepidopteran pests. From plant emergence to tile 5th fully emerged leaf stage, >50% of the com flea beetles were recorded on the uppermost fully emerged leaf and the whorl leaves. For more mature sweet corn, 40-50% of the com flea beetles were recorded on leaves 4-6. The between-plant distribution pattern of adult com flea beetles fit a negative binomial distribution and was aggregated. The Wald sequential probability ratio test was used to develop sequential sampling plans for different combinations of type I and II errors, and 2 sets of decision rule boundaries. The sampling plans were validated and the effect of truncation at 100 samples examined by Monte Carlo simulation techniques. With the upper boundary of the decision rule set at the current threshold, the sampling plan would be reasonably cost effective and compatible with the lepidopteran sampling plan, although the type II error is relatively high.