New Study Shows GM Crops Can't Always Fight Off Insect Pests

A new field study has revealed new evidence that genetically modified crops can have diminishing success at fighting off insect pests. The study coming from North Carolina State University and Clemson University was  published in the journal Environmental Entomology.

The work was supported, in part, by Monsanto – which developed the GM corn that produces Cry1Ab. Researchers found that the toxin used in genetically modified (GM) corn is having little impact on the corn earworm.

Corn earworm is the crop pest meant to be targeted in GM corn. This is consistent with predictions made almost 20 years ago. These were mostly ignored.

This study may serve as a red flag for future ventures. Due to the probability of the development of resistance in agricultural pests to GM crops. GM corn produces a Bacillus thuringiensis (Bt) protein. Bt produces a toxin called Cry1Ab. It was originally designed to attack European corn borer and went on the market in 1996.

In the late 1990s, scientists found that Bt/Cry1Ab was also fairly affective against the corn earworm. But enough earworms were surviving to lead to bug resistance to Cry1Ab.

More than 15 years later, more research out of NC State researcher looks into previous prediction.

Observational study in the field to see if there any indication that earworm was becoming resistant to Bt/ Cry1Ab. Evaluated corn crop sites in both North Carolina and South Carolina over two years.

In the late 1990s, Cry1Ab reduced both the number of pest larvae and the size of the larvae, compared to non-Bt corn. NOW à Cry1Ab has little or no effect on number or size of larvae compared to non-Bt corn.

Results seem to be that earworms have developed resistance to toxin used in GM corn.

More research needs to be done because this was a a field experiment, rather than an experiment done in a laboratory setting with pure Cry1Ab toxin. But it does show the real world effects of genetically modified crops. Currently, agriculture companies have already developed new, more effective Bt toxins for use against the pest and no impact financially has been made.

These findings are a reminder that we need to pay attention to potential clues about developing resistance. We can’t expect there to always be a new GM toxin available