Potential for Resistance to Bacillus thuringiensis: Colorado Potato Beetle (Coleoptera: Chrysomelidae)—A Model System

Abstract

A theoretical basis for resistance development to Bacillus thuringiensis by insect pests is presented with examples. The Colorado potato beetle, Leptinotarsa decemlineata (Say), is used as a model organism for discussing potential for resistance development, and operative factors that could influence resistance development are presented. The use of transgenic plants that produce high expression of the delta-endotoxin are likely to select for resistance to this toxin within six generations, based on a simple single-gene model in which a seed mixture of transgenic plants and nontransgenic plants was used. However, if the carrying capacity of the susceptible plant population is included in this model, resistance could take as few as four generations. Plants expressing low levels of toxin, which would inhibit rate of larval development, may provide the best use for transgenic plants; yet, even this approach presents possible problems.