John A. Miranowski and Katherine M. Lacy
Iowa State University

The Bt trait to control Western Corn Rootworm (WCR) in transgenic corn was first introduced in 2003. By 2014, about 80% of corn planted contained a Bt trait, significantly reducing corn insecticide use. This rapid and widespread adoption has led to resistance development in some Bt alleles. The near-term solutions to resistance development include voluntary adoption of resistance management practices (RMPs) including crop rotations, chemical controls, and development of new Bt alleles and other control technologies. Our results indicate that if the farmer goal is to maximize net returns or longer-term net present value per acre, crop rotations always dominate continuous corn. We also consider possible spillovers of resistance on neighboring farmers from mobile WCR. Generally, we conclude that this should not be a serious issue, especially if neighbors use RMPs.

Key words: Common pool resource, game theory, pest-control efficacy, resistance management practices, Western corn rootworm.