Author Information

Kenneth J. Koehler

Abstract

The bean leaf beetle (Cerotoma trifurcata) is a significant soybean pest in the Midwest. The possibility of reducing crop damage by disrupting the synchrony between emergence of F2 adults and the availability of young green pods requires an increased understanding of bean leaf beetle (BLB) phenology. An important consideration in predicting emergence of F2 adults is the influence of temperature on the rates of egg and larval development. In this article we concentrate on the analysis of data from a controlled study of the effects of temperature on both the hatch time distribution and the viability of BLB eggs. Several temperature levels are considered with a different number of egg cohorts exposed to each of several temperature levels. Hatch time observations for individual eggs are subject to both interval and right censoring, and inspection schedules vary across cohorts. Limited failure population (LFP) models with Weibull hatch time distributions are used to estimate parameters of the hatch time distribution and the proportion of viable eggs at each temperature. These estimates are used in the subsequent weighted least squares estimation of curves for predicting the proportion of viable eggs and the inverse median of the hatch time distribution as functions of temperature. Bootstrap procedures are used to estimate variances that properly account for within cohort correlations. The importance of replicating experiments for different temperature levels is illustrated.

Keywords

Bootstrap estimation, censored data, limited failure survival models

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Apr 24th, 6:30 PM

A BOOTSTRAP ANALYSIS OF TEMPERATURE EFFECTS ON BEAN LEAF BEETLE EGG HATCH TIMES

The bean leaf beetle (Cerotoma trifurcata) is a significant soybean pest in the Midwest. The possibility of reducing crop damage by disrupting the synchrony between emergence of F2 adults and the availability of young green pods requires an increased understanding of bean leaf beetle (BLB) phenology. An important consideration in predicting emergence of F2 adults is the influence of temperature on the rates of egg and larval development. In this article we concentrate on the analysis of data from a controlled study of the effects of temperature on both the hatch time distribution and the viability of BLB eggs. Several temperature levels are considered with a different number of egg cohorts exposed to each of several temperature levels. Hatch time observations for individual eggs are subject to both interval and right censoring, and inspection schedules vary across cohorts. Limited failure population (LFP) models with Weibull hatch time distributions are used to estimate parameters of the hatch time distribution and the proportion of viable eggs at each temperature. These estimates are used in the subsequent weighted least squares estimation of curves for predicting the proportion of viable eggs and the inverse median of the hatch time distribution as functions of temperature. Bootstrap procedures are used to estimate variances that properly account for within cohort correlations. The importance of replicating experiments for different temperature levels is illustrated.