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Mixing Reverses Pest Resistance to Biotech Cotton

Researchers at University of Arizona (UA) and Beijing’s Institute of Plant Protection discovered an unexpected strategy that can delay, and even reverse, the evolution of resistance by pests to genetically engineered crops. A new study reveals the success of hybridizing genetically engineered cotton with conventional cotton to reduce resistance in the pink bollworm, a voracious global pest.

Cotton, corn, and soybean have been genetically engineered to produce pest-killing proteins from the widespread soil bacterium Bacillus thuringiensis, or Bt. These Bt proteins are considered environmentally friendly because they are not toxic to people and wildlife. They have been used in sprays by organic growers for more than 50 years, and by millions of farmers worldwide in engineered Bt crops planted on more than 1 billion acres since 1996. Unfortunately, without adequate countermeasures, pests can quickly evolve resistance.

The ingenious strategy used in China entails interbreeding Bt cotton with non-Bt cotton, then crossing the resulting first-generation hybrid offspring and planting the second-generation hybrid seeds. This generates a random mixture within fields of 75 percent Bt cotton plants side-by-side with 25 percent non-Bt cotton plants.

"Because cotton can self-pollinate, the first-generation hybrids must be created by tedious and costly hand pollination of each flower. However, hybrids of the second generation and all subsequent generations can be obtained readily via self-pollination. So, the hybrid mix and its benefits can be maintained in perpetuity," said Bruce Tabashnik, researcher at UA.

NIFA supports the research through the Biotechnology Risk Assessment Grant Program.

Read the full story at UANews.

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Plant health, production, and products
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