For example, adaptation of a pest to an environmentally pesticidal substance produced by a transgenic plant may cause farmers to return to or begin the use of a conventional chemical pesticide with toxic effects on nontarget organisms. Also, adaptation of a pest to one type of transgenic pest-protected plant could result in its replacement with a novel transgenic pest-protected plant for which there is less information regarding health and environmental impacts.

Our understanding of the evolution of adaptation to pest-protected plants is still limited, but there is reasonable expectation that specific approaches to the development and deployment of transgenic pest-protected crops can substantially delay the evolution of pest adaptation. The committee found that

Although EPA has worked actively to develop useful resistance management plans for crops containing Bacillus thuringiensis (Bt) toxins, the agency has not articulated a general policy indicating when it believes it should require the development of resistance management plans for specific transgenic pest-protected crops.

The committee recommends that EPA continue to deal seriously with Bt resistance management (section 1.6.1), and it should also begin to consider resistance management strategies for other transgenic pest-protected plants. Specifically,

If a pest protectant or its functional equivalent is providing effective pest control, and if growing a new transgenic pest-protected plant variety threatens the utility of the existing uses of the pest-protectant or its functional equivalent, implementation of resistance management practices for all uses should be encouraged (for example, Bt proteins used both in microbial sprays and in transgenic pest-protected plants).

2.10 RECOMMENDATIONS

  • When the active ingredient of a transgenic pest-protected plant is a protein and when health effects data are required, both short-term oral toxicity and potential for allergenicity should be tested. Additional categori.es of health effects testing (such as carcinogenicity) should not be required unless justified.

  • The EPA should provied clear, scientifically justifiable criteria for establishing biochemical and functional equivalency when registrants request permission to test non plant-expressed proteins in lieu of plant-expressed proteins.



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