 The study found that the corn earworm has developed resistance to three different types of BT toxins, cry1ob, cry2ob2, and cry1a.105. This suggests that the use of BT crops may not be sustainable if the insects continue to develop resistance to the toxins. To prevent further development of resistance, it is important to implement better resistance management practices such as rotating between different BT varieties or using multiple BT proteins in one variety. This article was authored by Galen P. Dively, Tom P. Kuer, Sally V. Taylor, and others.