Gene flow from Bt transgenic corn to nonBt corn: can refuges speed the evolution of pest resistance?

摘要

Bacillus thuringiensis transgenic corn kills several pest species, but its usefulness is dependent on the prevention of pest resistance. To slow resistance to toxins in Bt crops, they are supposed to have high expression levels and nonBt refuges planted near the Bt crops. However, pollen from Bt crops such as corn can fertilize nonBt plants, causing toxin expression in the seeds or kernels of the nonBt plants. This paper examines how gene flow from Bt to nonBt corn affected toxin expression in nonBtrefuges. CrylAb genes from Bt hybrids were spread for up to 32 m across nonBt refuge plots with moderate to low toxin levels throughout the nonBt refuge. These findings were used in a simulation model to determine the effects of Bt toxin expression in refuges on the development of resistance to Bt toxins by pests. Results indicate that refuges must be located at a distance, dependent on wind speed and pollen movement, from Bt plantings, in order to act as a refuge or they may actually increase the rateof resistance evolution in pests.