Pests are evolving to become resistant to genetically engineered crops.
Bruce E. Tabashnik, regent’s professor and head of the department of entomology at the University of Arizona, looks to stay one step ahead.
My research team studies the evolution and management of insect resistance to crops genetically engineered for pest control. Current work focuses on resistance to insect-killing proteins from the bacterium Bacillus thuringiensis (Bt). These Bt proteins are highly effective against some key pests but are not toxic to most other organisms including arthropod natural enemies, wildlife and people. Transgenic Bt corn and cotton have been planted by millions of farmers on a cumulative total of more than 2 billion acres worldwide during the past 25 years. Our work ranges from analyses of the genomics of resistance to global patterns of field-evolved resistance to Bt crops. Progress is facilitated by synergistic collaborations that benefit from expertise in molecular and population genetics, ecology, modeling, and pest management.
Nature’s Sneaky Two-Step Keeps Crop Pests Guessing
Genetically engineered crops that help to control pests have been a game-changer for farmers around the world. These crops produce proteins from a natural soil bacterium called Bacillus thuringiensis or Bt, which are deadly to certain insect pests—but safe for people, pets, and wildlife. This helps to reduce insecticide sprays, which is good for the environment, the food supply, and farmers’ bottom line. The catch? Some pests are adapting by evolving resistance, which puts this eco-friendly approach at risk.
I’m part of a team of scientists at Nanjing Agricultural University and the University of Arizona that might have figured out how to stay one step ahead of these bugs. We discovered that one Bt protein, called Cry1Ab, actually delivers a one-two punch. It uses not one but two separate pathways to kill the Asian corn borer—a close relative of the European corn borer, which devastates corn in the U.S. and Canada. That means even if the pest mutates to block one path, the other still gets the job done. Only if both paths are disabled can the pest survive.
This natural strategy for delaying pest resistance could be harnessed to enhance sustainability by seeking native Bt proteins or designing novel Bt proteins that attack pests via multiple pathways. By using Bt proteins that have these built-in “backup systems,” we could slow down resistance and keep this powerful pest-fighting tool working for future generations.
Through this discovery, nature gave us a clue. Now it’s up to us to use it wisely.
