Bt Corn Refuge...In a Bag
Researchers know that without a refuge to provide susceptible individuals in the population, genetically resistant CRW are more likely to mate with each other causing wide-spread resistance to the Bt protein to evolve in the CRW population much quicker. Due to the need for a refuge and to ensure that growers comply with refuge requirements, scientists have developed the Refuge-in-a-Bag (RIB) concept.
RIB is a mixture of rootworm-protected Bt corn seed and non-Bt corn (can be Bt corn for controlling lepidopteran insects) seed in the same bag. The bag contains the required percentage of non-Bt corn and ensures that farmers plant the refuge at the same time they plant the Bt corn. A benefit of this approach is that the non-Bt plants will be spread throughout the field which may provide better distribution of survivors from the refuge to mate with beetles emerging from rootworm Bt corn compared to block refuges that are planted in one area of the field. Researchers are using simulation modeling techniques to compare RIB versus block refuge scenarios under a variety of conditions to identify key factors that influence potential rates of resistance evolution.
Before answering the following question, watch this video presentation on selection pressure, refuge in a block vs. Refuge-in-a-Bag, and the occurrence of resistant CRW populations to rootworm Bt corn.