Ecological Effects of Genetically Engineered Crop Plants


The bacterium Bacillus thuringiensis makes a family of toxins which have been used to control certain insect larvae; that is, caterpillars. Bt is a comparatively clean pesticide: it is a protein, actually a slurry of many different toxins, that are poisonous to its target organisms but not to the family pooch. Likewise Bt toxins, being proteins, break down fairly rapidly and do not persist or build up in the environment.

Montesano developed the technology to put the genes for Bt toxin into corn, cotton, and other crops, allowing them essentially to make their own pesticide. Thus any caterpillar that ate part of a Bt engineered plant would be poisoned. After this technology was quickly and widely adapted in the U.S. a Cornell University researcher noticed that high doses of pollen from Bt-corn plants was toxic to Monarch butterfly larvae. Subsequent research has found that the toxin is highly unlikely to harm Monarchs under any reasonable scenario. The Monarch scare turned out to be a false alarm, but what questions should we be asking before we release genetically engineered plants?

We spoke with Allan Felsot about the monarch story and its implications for biotech as applied to plants.

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