A SIMULATION MODEL OF NORTHERN CORN ROOTWORM, DIABROTICA BARBERI SMITH AND LAWRENCE (COLEOPTERA: CHRYSOMELIDAE), POPULATION DYNAMICS AND OVIPOSITION: SIGNIFICANCE OF HOST PLANT PHENOLOGY

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Abstract
Based on field and laboratory research, a simulation model was developed that describes the within-season population dynamics and oviposition of adult northern corn rootworm beetles, Diabrotica barberi Smith and Lawrence, in field corn, Zea mays L. Particular emphasis was placed on the role of host plant phenology. Overall goals were to examine the contribution of insect dispersal to the dynamics of single fields, and provide a means of examining the factors influencing insect/plant synchrony and the relationship between adult abundance, oviposition, and crop phenology. The model is process-oriented and integrates component models for corn phenology, and adult emergence, mortality, dispersal, reproductive development, and oviposition.Comparison of field data with simulations excluding dispersal generally indicated a net emigration of beetles from corn fields on a season-long basis; however, the timing and magnitude of dispersal from fields were strongly influenced by the relative timing of corn flowering, beetle sex, and the reproductive maturity of females. Simulation and field data were used to describe and estimate the parameters of a component model for dispersal incorporating these features. Various component models and the overall system model were validated against independent field data. The model provided adequate prediction of adult emergence and crop phenology for three varieties on which it was based, but consistently underpredicted total oviposition and poorly predicted the phenology of two different corn varieties. Overall, the model accurately predicted seasonal population trends, the relative abundance of mature females, and the relationship between adult abundance and oviposition.