The researchers attribute the collateral benefits for non-Bt farmers to area-wide suppression of corn borers stemming from long-term plantings of Bt-protected crops. Potato, green bean and other host crops also stand to benefit from area-wide reductions of corn borers, the researchers said.  The team’s Science report also highlights the importance of refuge crops—planting non-Bt crops adjacent to fields of Bt crops, providing a refuge to which the pests can retreat—and other strategies to slow the corn borer’s ability to develop resistance to Bt and thus maintain the insecticidal proteins’ long-term effectiveness.

The Bt proteins provide the plant with a built-in defense against attacks by the larvae of European corn borers and other insect pests.  Larvae that ingest the protein soon stop feeding and die, typically within 48 hours. In addition to reducing the use of insecticides that also can endanger beneficial insects, the Bt defense strategy helps prevent harmful molds from gaining entry to the plants via wound sites from borer feeding. Some of these molds, like Fusarium, produce mycotoxins that can diminish the value and safety of the crop’s kernels.