ANALYSIS OF A SIMULATION MODEL OF NORTHERN CORN ROOTWORM, DIABROTICA BARBERI SMITH AND LAWRENCE (COLEOPTERA: CHRYSOMELIDAE), DYNAMICS IN FIELD CORN, WITH IMPLICATIONS FOR POPULATION MANAGEMENT

Abstract

AbstractAnalyses were performed on a simulation model describing the population dynamics of adult Diabrotica barberi Smith and Lawrence in field corn. Overall goals were to gain a better understanding of the dynamics of this insect/plant system and explore possibilities for improved population management. Parametric sensitivity analyses revealed that model behavior was moderately sensitive to changes in the timing of female emergence, rates of immature female dispersal at peak flower, fecundity, and rates of reproductive development. Model behavior was highly sensitive to changes in age-specific oviposition rates, and to factors determining the seasonal timing and duration of the flowering period of corn. Alteration of planting dates, variations in seasonal temperature patterns, and year-to-year variation in beetle dispersal patterns greatly affected the simulated relationship between adult abundance, oviposition, and crop phenology, and the synchronization of beetle populations with flowering corn. Factorial analyses indicated that manipulation of planting dates, variety, and the duration of the flowering period represent equivalent alternatives for reducing site-specific oviposition. Factorial analyses further suggested that the timing of emergence and dispersal, relative to flowering, are the major factors contributing to the presence of beetles during the flowering period, but their relative contributions depend on the seasonal time of flowering. The timing of emergence is more important in early-flowering fields but dispersal becomes more important for fields flowering later in the season. Simulation was used to examine the relationship between adult abundance, oviposition, and crop phenology and to formalize hypothetical improvements in current action thresholds for making recommendations for corn rootworm control based on adult sampling. Overall, analyses have allowed important insights into the behavior of this insect/plant system.