A new study just published this week by Cornell entomology professor Anthony Shelton shows that growing Bt corn can marked reduce the application of insecticides and increase corn yields. The article, published in the Journal of Economic Entomology is titled “Multi-State Trials of Bt Sweet Corn Varieties for Control of the Corn Earworm.”
Bacillus thrunginesis, or Bt, is a common soil-based bacterium that has been used in both organic and conventional farming for nearly 50 years, and has been found to be toxic to Lepidoptera such as the corn earworm. In the 1990s, it was found the Cry genes express the Bt toxin, and in 1993, Ciba-Geigy described the first transgenic corn (maize) with the Cry gene inserted.
Bt corn now represents nearly 90% of the corn grown in the US, although the amount of sweet corn (for eating) is less than that because of activities of pressure groups and the reluctance of grocers to resist the pressure.
However, Shelton’s research shows very significant advantages for Bt sweet corn. They report that Bt corn dramatically reduces the need for pesticides and increases profits.
They analyzed the performance of Bt corn and genetically identical conventional corn in fields in New York, Minnesota, Maryland and Ohio and found that the Bt corn consistently performed better even compared to corn sprayed with conventional insecticides.
“One of the most spectacular examples occurred in New York plots in 2010,” says Shelton. “The Bt sweet corn had 99 to 100 percent marketable ears without any sprays and, even with eight conventional insecticide sprays, the non-Bt corn had only 18 percent marketable ears. This wasn’t much better than the 6 percent marketable ears produced in the plots that received no sprays at all.”
Thus, they believe that reduced inputs in raising corn can lead to greater profits.
Long term studies have shown that Bt corn poses no health risk to animals or humans, since the bacterium is common in the soil already.