Fees or refuges: which is better for the sustainable management of insect resistance to transgenic Bt corn?

Abstract

The evolution of resistance in insect pests will imperil the efficiency of transgenic insect-resistant crops. The currently advised strategy to delay resistance evolution is to plant non-toxic crops (refuges) in close proximity to plants engineered to express the toxic protein of the bacterium Bacillus thuringiensis ( Bt ). We seek answers to the question of how to induce growers to plant non-toxic crops. A first strategy, applied in the United States, is to require Bt growers to plant non- Bt refuges and control their compliance with requirements. We suggest that an alternative strategy is to make Bt seed more expensive by instituting a user fee, and we compare both strategies by integrating economic processes into a spatially explicit, population genetics model. Our results indicate that although both strategies may allow the sustainable management of the common pool of Bt -susceptibility alleles in pest populations, for the European corn borer ( Ostrinia nubilalis ) one of the most serious pests in the US corn belt, the fee strategy is less efficient than refuge requirements.