Document Type

Thesis - Open Access

Award Date


Degree Name

Master of Science (MS)

Department / School

Mathematics and Statistics

First Advisor

Robert J. Lacher


A computer model was developed which used weather data and initial field counts of green-bug aphids to predict the behavior of the aphid population throughout the season. The model considered the effects of heat, food supply, predati6n and rainfall on the population. Data were obtained on the life cycle of aphids grown in a controlled laboratory setting. These data were used to postulate a stochastic model of aphid growth which could be applied to a population in the field. A modified Leslie matrix model was used to predict the population's future behavior. Factors were then added to this basic model to account for mortality due to old age and predation, and the fecundity of the adult population. The completed model was compared with the actual field data obtained for several years. This comparison showed that the model generally performed well. As a last step, sensitivity analysis was done to determine which factors in the model would most profit by closer scrutiny. It was found that predation, in particular needed to be analyzed more carefully.

Library of Congress Subject Headings

Insect populations -- Mathematical models

Wheat -- Diseases and pests




Number of Pages



South Dakota State University