Cornell Study Takes In-Depth Look at Stacked-Trait Bt Corn
Cornell researchers find that if insects are exposed to single- and double-gene Bt corn at the same time, they may be more likely to develop resistance.
Compiled by staff
Published: Jun 7, 2005
Researchers at Cornell University have new insight into the potential development of insect resistance to Bt corn, finding that one approach many tout as a big help in prevention may cause other issues.
In nearly 10 years of using the technology, there has been little indication that resistance is developing, due in part to U.S. farmer compliance with required resistance management strategies. Moving ahead, many point to multi-trait Bt corn products that could enhance that resistance prevention. But the researchers found something different.
They discovered that when a population of insects was exposed to both single- and double-gene Bt traits at the same time they were much more likely - after 24 to 26 generations - to develop resistance (insects can have up to two or three generations in a season). Seed companies are working on stacking Bt traits in an effort to enhance resistance, and the Cornell work shows that practice works very well when there are only stacked Bt's present. However, when the test insect population was exposed to both single- and two-gene Bt plants at the same time they develop resistance to the two-gene Bt much faster.
The researchers note that the advantage of the stacked-trait Bt plants may be compromised if the plants share similar toxins with single-gene plants planted at the same time. This is a greenhouse study using broccoli plants modified with single- and dual-gene Bt technology working with a synthetic population of the diamondback moth. The researchers say the results of the experiment "agree with the predictions of a Mendelian deterministic simulation model and have important implications for the regulation and deployment of [stacked] Bt plants." Researchers and regulators are currently evaluating resistance management strategies for stacked-trait Bt products under review.
The study was published online Monday at the National Academy of Sciences Web site, and will appear in an upcoming issue of the Proceedings of the National Academies of Science.
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