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TRANSGENIC PLANTS AND WORLD AGRICULTURE
The real potential of GM technology to help address some of the most serious concerns of world agriculture has only recently begun to be explored. The following examples show how GM technology can be applied to some of the specific problems of agriculture, indicating the potential for benefits.
There is clearly a benefit to farmers if transgenic plants are developed that are resistant to a specific pest. For example, papaya-ringspot-virus-resistant papaya has been commercialized and grown in Hawaii since 1996 (Gonsalves 1998). There may also be a benefit to the environment if the use of pesticides is reduced. Transgenic crops containing insect-resistance genes from Bacillus thuringiensis have made it possible to reduce significantly the amount of insecticide applied on cotton in the United States. One analysis, for example, showed a reduction of 5 million acre-treatments (2 million hectare-treatments) or about 1 million kilograms of chemical insecticides in 1999 compared with 1998 (U.S. National Research Council 2000). However, populations of pests and disease-causing organisms adapt readily and become resistant to pesticides, and there is no reason to suppose that this will not occur equally rapidly with transgenic plants. In addition, pest biotypes are different in various regions. For instance, insect resistant crops developed for use in the United States and Canada may be resistant to pests that are of no concern in developing countries, and this is true both for transgenic plants and those developed by conventional breeding techniques. Even where the same genes for insect or herbicide resistance are useful in different regions, typically these genes will need to be introduced into locally adapted cultivars. There is need, therefore, for more research on transgenic plants that have been made resistant to local pests to assess their sustainability in the face of increased selection pressures for ever more virulent pests.