A MODEL SIMULATING THE INTERACTION OF CORN PLANT GROWTH AND CORN ROOTWORM DEVELOPMENT

ERIC LEE CHIEN HSIN PANG, Purdue University

Abstract

A model was constructed to examine the changes in rootworm population with food availability and the effect on plant growth and development caused by rootworm feeding. The top model simulates dry matter production through tasseling. The root model depicts root growth and proliferation in a vertical 2-dimensional soil slab, and the rootworm model simulates rootworm movement, development, and feeding in the soil slab. Calibration and validation studies showed that the root model can mimic root growth fairly well in terms of total dry matter accumulations through time and for roots originating at each individual node. The insect model did very well in predicting the phenological events for rootworm development, though the model lagged behind actual field events by a few days late in the season. The top model predicted top growth accurately at the beginning of the season. But later in the season, the model's predictions greatly underestimated the field data. When insect feeding was introduced to the coupled top and root models, simulation results showed a lack of feedback between the top and root models. This lack of feedback was traced to the high root growth rate values used in the model. Under normal circumstances, the root model acts somewhat independently of the growth rate, and growth is limited only by the availability of carbohydrate. When root mass is reduced by feeding, the growth rates come into play leaving the root carbohydrate pool in an unbalanced state, with the roots taking more carbohydrate than actually needed. Experiments to determine root consumption for rootworms were unsuccessful. Field data collected for two seasons were not sufficient to determine the effects of rootworm feeding on top and root dry matter accumulations. Reasonable data for plant growth and relative rootworm density up to tasseling were obtained however.

Degree

Ph.D.

Subject Area

Entomology

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