Sir -- A substantial acreage of US fields is now given over to transgenic plants that produce an insecticidal protein (a derivative of the Bacillus thuringiensis insect-control protein CryIA, also known as Bt toxin). In an effort to restrict the spread of resistance to Bt toxin, the use of refuges -- areas of non-transgenic plants planted close to the transgenic variety -- has been adopted. In News and Views1, M. J. Crawley wrote: "The strategy might be expected to work because resistance is usually a genetically recessive trait". However, F. Huang et al (2) have recently shown that, for the European corn borer, resistance is an incompletely dominant trait. Although the significance of these results has been challenged (3) , they may mean that refuges will not work for this insect, a major agricultural pest in the United States.

This is something that should have been established before the widespread planting of transgenic corn. It's hardly surprising that there is distrust of agri-biotech companies (4) , when they do not put significant effort into answering the basic questions that enable such risks to be evaluated.

Jonathan Ewbank
Centre d'Immunologie de Marseille-Luminy, 163 Avenue de Luminy, Case 906, 13288 Marseille Cedex 9, France

References

1. Crawley, M. J. Nature 400, 501-502 (1999). Links
2. Huang, F., Buschman, L. L., Higgins, R. A. & McGaughey, W. H. Science 284, 965 (1999). Links
3. Tabashnik, B. E., Earle, E., Roush, R. & Shelton, A. M. ISB News Report (September 1999). Links
4. Haerlin, B. & Parr, D. Nature 400, 499 (1999). Links