Bt technology helps increase yield, decrease sprays and increase insect diversity
Twenty years ago the world of agriculture was very different. Using biotechnology to ward off insects was a mere concept until the introduction of Bt cotton in 1996. Today, farmers continue to reap yield and environmental benefits.
Bt, Bacillus thuringiensis, is a protein naturally found in soil and has been used in foliar insecticides since the 1950s. In 1996, Bt proteins were inserted into cotton plants through biotechnology. Now when insects bite the plant, the protein kills them within the gut. Bt won’t hurt people or certain kinds of insects since it only works on specific stomach types.
Thanks to Bt technology, farmers aren’t spraying 10 times for caterpillar pests anymore, says David Kern, associate professor of cotton and Jack Hamilton Regent’s Chair in cotton production at Louisiana State University. “They’ll spray maybe once or twice, but in many areas they rarely spray,” he adds.
Surprisingly, one of the biggest benefits of Bt cotton is increased insect diversity. Fewer sprays allow beneficial insects to survive and, in some cases, help manage damaging pests.
“Beneficial insects are an important component in managing bollworm and budworm in cotton,” says Joel Faircloth, cotton development specialist for PhytoGen cottonseed. “When you wipe out beneficial insects with a non-selective insecticide overspray, you reduce the level of protection due to predation in subsequent moth flights.”
Since the introduction of Bt cotton, U.S. farmers have increased yields by 9% to 11% while reducing insecticide use by 17%. Yield is always top of mind, but in today’s world, environmental stewardship has to be as well. “We can’t lose sight of all the environmental benefits,” says Shannon Hauf, Monsanto global cotton, wheat and specialty crops lead. “Those are the things we think about 20 years later.”
Environmental benefits have paid dividends to farmers’ by an additional $21 to $61 per acre from increased yield and reduced insecticide costs.
Bt Resistance in Cotton Pests
Since Bt technology reduces the number of insecticide sprays, some insects previously killed, even when they weren’t the primary target, often live. Stink bugs and plant bugs, for example, have become a problem for farmers.
Increased pressure from certain insects raises a red flag for farmers with resistance concerns. However, the issue of Bt resistance is tricky in cotton as there is no confirmation of an insect being resistant to traits in the crop, says Robert Bowling, Texas A&M Extension entomology specialist. “Even though we have some worms surviving the Bt protein, at this point we can’t say they’re resistant.”
Bowling says in cases where worms get through, it’s more likely some varieties or plant parts might not express Bt as much. Some insects, such as bollworm, are less susceptible to the Bt trait and exploit weak varieties or plant parts. Once the worm grows bigger it can withstand the Bt protein even more.
One of the most effective steps you can take to ward off potential resistance is through stewardship. Get out into your fields and scout insect pressure, checking for any possible resistance. Remember, just like in weed control, more modes of action help decrease the likelihood of a pest becoming resistant.
“Now the cotton industry is moving toward three stacked genes to improve insect protection and minimize the development of resistance,” says Steve Nichols, Bayer head of agronomic services.