A pest and resistance management simulation model for the Colorado potato beetle on potatoes.

摘要

The purpose of this dissertation is the design and implementation of a deterministic simulation to be used for Colorado potato beetle pest and resistance management on the Eastern Shore of Virginia. For the potato growers of this region, pesticides are the primary means of controlling the Colorado potato beetle, the region's major potato pest. However, the beetle is infamous for its relatively rapid development of resistance to pesticides.; On one hand, the farmer wishes to maximize his current season's final yield, and applying pesticides for Colorado potato beetle control furthers this objective. On the other hand, applying pesticides leads to the development of pesticide resistance, which is marked by increased difficulty and cost in controlling beetle populations over time and possibly by an eventual complete loss of control. Unlike other pests for which resistance-management optimization models have been created, Colorado potato beetle resistance profiles, the levels of resistance to the set of pesticides used in their control, vary from field to field rather than being homogenous over a region. Therefore, a potato farmer has some control over his pests' resistance profile. Thus, minimizing the rate at which resistance develops is the second objective influencing a farmer's pesticide-application decision making.; This simulation is intended to be part of a bicriteria optimization model whose purpose is to search for efficient pesticide-application strategies. In this optimization model, a pesticide-application strategy, including the pesticide-application times and intensities for each season in the planning horizon, would be given to the simulation. Implementing this application strategy, the simulation would then run and return to the optimization portion of the program a measure of resistance development and the total discounted profit for the planning horizon. The optimization portion of the program would then use these measures of strategy performance to search for improved strategies.; In exploring the design of this optimization model, it was found that no simulation for the Colorado potato beetle which included all elements of the pest-crop system already existed.; The simulation which this dissertation describes incorporates all aspects of beetle life processes, pesticide resistance, and potato growth needed to adequately predict the consequences of a pesticide-application strategy. Since amount of foliage consumed and pesticide effectiveness vary with beetle life stage, of which there are seven, the simulation contains a mechanism to mature beetles through their physical development. For pesticide resistance, it employs the appropriate type of genetic inheritance mechanism of resistance for the pesticides included in the simulation. Its crop-growth model, adapted from that of Johnson, Johnson, and Teng (1986), adds to plant growth many times during a day so that the effects of defoliation are incorporated into plant growth as occurs in reality. (Abstract shortened by UMI.)