Bt Toxin Resistance: an Evolutionary Action

Researchers from the University of Arizona led by Bruce Tabashnik, a renowed entomologist, have recently published an article in Nature Biotechnology on the possibility of six chewing insect pests gaining resistance to the Bt toxins contained in transgenic Bt cotton and Bt corn. Analysis conducted by research collaborators in Australia, China, Spain and the USA proved that the resistance of the southeast Asian cotton bollworm (Helicoverpa zea) to Bt cotton could have arisen from a natural evolutionary process. The other insect pests however, such as the pink bollworm, the most significant pest in the southwest USA, as well as the corn borer found in Europe and Asia have not changed their sensitivity to the Bt toxin.

The economic impact of the increased  resistance of the cotton bollworm to Bt  cotton is diminishing as the hectarage of Bt cotton with the single gene cry2Ac is reduced. In addition, Bt cotton with the two-stacked genes cry2Ac and cry2Ab  has become available for cultivation to control the pest. Other means of insect stewardship are discussed in the full report.

For details, see the full research report at: http://www.nature.com/nbt/journal/v26/n2/pdf/nbt1382.pdf