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American Association for the Advancement of Science

Planting 2 types of corn pays off for farmers

Non-Bt corn stalks with feeding damage vs. Bt maize with no feeding.
[Image © Science/AAAS]

Genetically modified (GM) corn plants can kill insect pests and reduce damage to other neighboring crops as well—but farmers who plant both types of corn at the same time save the most money, researchers say. William Hutchison and colleagues came to this conclusion after they studied the effects of GM corn on the European corn borer moth, a corn-killing pest that was accidentally introduced to the Midwestern United States in 1917. Each year, researchers estimate that the moth causes about one billion dollars in crop damages.

Female European corn borer moths have dull, buff colored wings while males have brown colored wings.
[Image © Science/AAAS]

The modified corn that the researchers examined was engineered to express insect-killing proteins from the bacterium Bacillus thuringiensis (Bt). Hutchison and his colleagues found that this Bt-expressing corn, which has become very popular on U.S. farms over the past decade, generally reduces populations of the corn borer moths so that both Bt-expressing corn and regular corn can both benefit from fewer insect pests. In this way, non-Bt corn pays off because farmers don't have to pay the higher price for Bt seeds, but they still receive some pest control from the neighboring Bt corn.

Hutchison and the researchers also say that too many Bt crops in one area could cause the moths to develop a strong resistance to the insect-killing proteins in Bt corn, and they highlight the need for "refuges" of normal crops near Bt crops so that such resistance does not develop too quickly in the moths. The researchers conclude that the economic benefits of these refuges of non-Bt corn can equal or even go beyond the benefits of Bt corn—and they say the best strategy for farmers right now seems to be growing both types of corn at the same time.


This research appears in the 08 October 2010 issue of Science.