It has been nearly a decade since several major transgenic Bt crops, such as cotton, corn, and potato, were first commercialized in the United States. Bt crops have become increasingly accepted by farm- ers as effective alternatives to chemical insecticide applications for control of key crop pests in both developed and developing countries (James, 2001). Because Bt crops have the characteristics of con- ventional plant resistance for crop protection, they have great appeal for crop production and man- agement systems. Based on ecological risk analysis of the toxicity and specificity of Bt Cry proteins and possible tritrophic interactions among Bt crops, herbivores and natural enemies, we see great potential for integrating Bt crops with biological control in IPM programs. This is especially true where Bt crops control key crop pests and allow survival and population growth of generalist natural enemies for effective biological control of secondary pests.
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