trophic levels that are consumed by nontarget organisms. However, the committee found that

Both conventional and transgenic pest-protected crops could have effects on nontarget species, but these potential impacts on nontarget organisms are generally expected to be smaller than the impacts of broad-spectrum synthetic insecticides, and therefore, the use of pest-protected plants could lead to greater biodiversity in agroecosystems where they replace the use of those insecticides.

Current criteria for commercialization of transgenic pest-protected plants includes several laboratory toxicity tests for nontarget organisms (see appendix B and section 3.1.2). In light of the above discussions, more field evaluations should be conducted to determine the impacts of specific pest-protected crops on nontarget organisms, compared to impacts of standard and alternative agricultural practices. The committee recommends that

Criteria for evaluating the merit of commercializing a new transgenic pest-protected plant should include the anticipated impacts on nontarget organisms compared with those of currently used5 pest control techniques.

2.7 GENE FLOW FROM TRANSGENIC PEST-PROTECTED PLANTS

Genes from one crop plant may be spread to other plants of the same or related species when pollen is transported by wind, bees, or other animal pollinators. Genes have been flowing from crops to weedy relatives of crop plants for centuries. Now it is also possible for fitness-enhancing transgenes to spread to weed populations. In this report, the committee uses the terms “weedy” and “invasive” in reference to plants that are unwanted in human-dominated or natural habitats. Many people think of weeds primarily as undesirable plants that infest agricultural fields, tree plantations, lawns, and other managed areas. However, natural and semi-natural habitats such as wetlands, coastal dunes, and rangelands are also harmed by the spread of weedy species. Weedy plants quickly colonize open space and may displace non-weedy species, as has occurred with kudzu, Scotch broom, spotted knapweed, and purple loosestrife, for example. Once established, these types of plants are often difficult to eradicate. Annual species release large quantities of long-

5  

Includes both chemical and non-chemical methods which are currently used.



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