You can’t fool Mother Nature: GM (Bt) crops not so pest resistant after all

February 9, 2008

A pest insect known as bollworm is the first to evolve resistance in the field to plants modified to produce an insecticide called Bt, according to a new research report.

Bt crops have been genetically altered to produce Bt toxins, which kill some insects. The toxins are produced by the widespread bacterium Bacillus thuringiensis, hence the abbreviation Bt.

University of Arizona entomologists looked at data from six experiments to monitor pests in fields sown with transgenic cotton and corn in Australia, China, Spain and the United States. They found evidence of genetic mutation among bollworms (Helicoverpa zea) in a dozen cotton fields sown in Mississippi and Arkansas between 2003 and 2006.

Opponents of GM technology, have long predicted that pests would become resistant to transgenic toxins, something that happens frequently in the case of chemical insecticides.

To overcome the resistance, scientists would have to use higher levels of toxins or different kinds, they say.

According to the USDA, in one year alone over 57 Million pounds of pesticide were used on U.S. cotton fields. The EPA considers 7 of the top 15 pesticides used on cotton as “likely” or “known” human carcinogens.



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