Entomologists and ecologists compared crop damage and insecticide use in four agricultural mid-Atlantic states: New Jersey, Delaware, Maryland, and Virginia. Their data came from the years before Bt corn was widespread (1976-1996) and continued after it was adopted (1996-2016). They also looked at the levels of the pests themselves: two different species of moths, commonly known as the European corn borer and corn earworm. They were named as scourges of corn, but their larvae eat a number of different crops, including peppers and green beans. After Bt corn was planted in 1996, the number of moths captured for analysis every night in vegetable fields dropped by 75 percent. The drop was a function of the percentage of Bt corn planted in the area and occurred even though moth populations usually go up with temperature. So the Bt corn more than counteracted the effect of the rising temperatures we’ve experienced over the quarter century covered by the study.
An anonymous reader quotes a report from Ars Technica: One of the great purported boons of GMOs is that they allow farmers to use fewer pesticides, some of which are known to be harmful to humans or other species. Bt corn, cotton, and soybeans have been engineered to express insect-killing proteins from the bacterium Bacillus thuringiensis, and they have indeed been successful at controlling the crops’ respective pests. They even protect the non-Bt versions of the same crop that must be planted in adjacent fields to help limit the evolution of Bt resistance. But new work shows that Bt corn also controls pests in other types of crops planted nearby, specifically vegetables. In doing so, it cuts down on the use of pesticides on these crops, as well.