ABSTRACT
INTRODUCTION Recent advances in molecular biology and genetics have led to the creation of exciting new opportunities in the field of agriculture. Some of the first and most widely-used genetically-engineered crops have been modified to express insecticidal crystalline (Cry) proteins derived from the bacterium Bacillus thuringiensis (Bt). These so-called Bt crops are protected from the feeding of various groups of herbivorous pest insects. In 1995 and 1996, varieties of potato, cotton and com expressing various Bt proteins were approved for commercial use in the United States. In Bt potato, the Cry3Aa protein provides protection against damage from the Colorado potato beetle. In Bt cotton and Bt com, the proteins expressed (CrylAc in cotton and CrylAb or CrylF in com) confer protection against a number of lepidopteran herbivores. The Bt cotton and Bt com products, in particular, are widely used (James, 2001). Bt cotton has since been registered for commercial use in Argentina, Australia, China, Columbia, India, Indonesia, Mexico, and South Africa. Bt com has a similar potential; in 2001, about 20 million acres of Bt com were planted in the United States, almost 40% of com acres in Argentina are occupied with Bt com, and smaller amounts were planted commercially in Canada, Spain, and South Africa. A critical part of the introduction of such products is to ensure their environmental safety. In this chapter, we
shall describe the safety assessment process used to evaluate the potential impact of Bt crops on non-target species, and we review the laboratory and field research that has been conducted in this area (see also Shelton et al., 2002 for a broader review of the impacts of Bt crops).
