Background Application to register Bt corn targeted at corn rootworm. These comments are submitted in response to Monsanto's request for registration. The registration application is the first for a Bt-corn variety engineered to control beetles. Bt toxins which are specific for moths, in particular, the European corn borer. Until the adoption of corn monoculture in the Midwest, beginning about 50 years ago, corn rootworms were minor pests.
Many farmers control the corn rootworm through crop rotations.
First, some western corn rootworm females have begun laying eggs in soybean fields in the fall. Then, in the spring, when the field is rotated to corn, the larvae hatch and begin feeding on the corn roots. Second, an increasing number of northern corn rootworms exhibit an extended egg diapause, that is, eggs, rather than hatching the first spring after they are laid, may pass through two or several winters before they hatch. Some of these worms may fortuitously encounter corn when they emerge. Comments and Recommendations 1.