Predicting Lesser Cornstalk Borer (Lepidoptera: Pyralidae) Larval Density From Estimates of Adult Abundance in Peanut Fields

Abstract

The abundance of larvae and adults of the lesser cornstalk borer was monitored in conventionally tilled and planted Florunner peanuts at the Wiregrass Experiment Substation in Headland, Ala. from 1984 to 1986. Larval abundance was monitored by soil sieving ca. weekly throughout the growing season. The abundance of adults was monitored weekly by flushing male and female moths from rows by beating plants with a stick. Regression was used to determine if adults in week ‘i’ can explain the variation in larval abundance in week ‘i + 1,’ over the three years of observation. The mean number of larvae from week ‘i + 1’ increased linearly with an increase in adult flush counts from week ‘i’ (P < 0.0001, r2 = 0.91), indicating that larval density could be predicted by adult abundance. The resulting equation had an intercept that was not significantly different from zero (P = 0.29) and a slope of 12.66 ± 0.88 (P < 0.0001), indicating that about 13 larvae/meter can be expected to be found one week later for each adult/meter flushed. Observations from five separate peanut fields were taken in 1990 to determine if adult counts do reflect larval abundance as predicted by the regression equation. Means from four of five model validation fields fell within the 95% confidence limits for the regression equation, indicating excellent agreement with the field data. This equation could be a significant addition to management of the lesser cornstalk borer, because the use of adult flush counts allows for the prediction of damaging and difficult to sample larval populations before they occur.