Study IDs Ways to Encourage ‘Refuge’ Planting, Slowing Resistance to Bt Crops

by Matt Shipman, North Carolina State University

A new study from North Carolina State University finds a significant shortfall in the amount of “refuge” cropland being planted in North Carolina – likely increasing the rate at which crop pests will evolve the ability to safely devour genetically engineered Bt crops. However, the study also identified actions that may make farmers more likely to plant refuge crops in the future.

For about 20 years, growers have made use of Bt crops to limit crop damage from pests. Bt crops, including corn, are genetically engineered to produce proteins from the Bacillus thuringiensis (Bt) bacterium. These proteins are harmless to vertebrates, but toxic to a specific class of invertebrate crop pests. Continue reading

Research team finds that natural enemies help delay insecticide resistance, protect Bt crops

Despite the controversy over them, transgenic crops have helped growers fend off some of the most destructive pests. The higher yield that results has provided consumers more affordable food. When used properly as a part of an integrated pest management program, transgenic crops can be an effective and economical way to manage certain pests, diseases and weeds. Unfortunately, as the failures of Roundup Ready crops have shown, transgenic crops are not sustainable when used as the sole pest management tactic.

When Bt technology came out, the Environmental Protection Agency instituted a requirement to have a “refuge” plot of crops not protected with Bt to maintain a population of pests that were not exposed to the Bt toxin. The refuge could be treated with an insecticide; it just couldn’t be treated with Bt. The theory behind the refuge was that having a plot of the crop that was treated with a different insecticide would give the pest species a non-Bt alternative, so that those individuals would still be susceptible to Bt, mate with individuals who had been exposed to Bt and pass on their Bt-susceptible genes to the next generation, therefore delaying resistance. Continue reading

Predators delay pest resistance to Bt crops

Crops genetically modified with the bacterium Bt (Bacillus thuringiensis) produce proteins that kill pest insects. Steady exposure has prompted concern that pests will develop resistance to these proteins, making Bt plants ineffective.

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How Do You Control Corn Earworm? Wake ‘Em Up!

A team of scientists in Ohio has discovered a new way to control Helicoverpa zea, or corn earworm. They have developed a chemical that interrupts the insect’s dormancy.

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Higher Crop Returns Don’t Negate Need for Thoughtful Pest Management

When corn prices suddenly rose dramatically in 2007, Illinois researchers reported that some farmers were willing to do anything to increase their yields. Many of them used products to combat pests that they didn’t even have.

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Researchers Validate Resistance Management Practices for Bt-crops

Crops genetically engineered with the toxin Bacillus thuringiensis (Bt) have been grown in the United States since 1996. Since then, concerns about pest resistance have grown, mainly because of observed resistance of the cotton bollworm (Helicoverpa zea), a major pest of cotton. According to a 2009 published study in the Journal of Economic Entomology, insect resistance to Bt can be monitored and prevented.

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Are Bt Crops a Silver Bullet or a Looming Disaster?

Cotton growers know the pest as the bollworm. Corn growers call it corn earworm. Tomato growers don it tomato fruitworm. By any name, the pest is Helicoverpa zea, and it’s the first pest to develop resistance to Bacillus thuringiensis.

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