Biotech Updates

GM Corn Summons Nematodes to Kill Voracious Rootworms

August 7, 2009

Researchers from the University of Neuchâtel in Switzerland have developed genetically modified corn plants that resist the dreaded Western corn rootworm by emitting a volatile chemical that summons insect-killing parasitic roundworms - a natural embodiment of the saying "my enemy's enemy is my friend."

Plants emit an array of volatile compounds when attacked by herbivorous insects. These compounds serve a variety of functions, including the attraction of the insects' natural enemies, or what scientists call "indirect defense". Root worm-infested corn plants, for instance, release (E)-beta-caryophyllene (EβC) to attract nematodes. But researchers found that after decades of breeding, most North American corn varieties no longer emitted the sesquiterpene and had lost the ability to attract beneficial nematodes.

Working with colleagues from the Max Planck Institute for Chemical Ecology, the Neuchâtel researchers introduced an EβC-synthase gene from oregano to a corn variety that normally does not emit the compound. Field trials of the GM corn variety were then conducted at the University of Missouri's Bradford Research and Extension Center in Columbia. The researchers found that in rootworm-infested field plots in which nematodes were released, the transgenic plants suffered significantly less root damage and had 60 percent fewer Diabrotica beetles emerge than in untransformed lines.

"Instead of using insecticides, the use of natural enemies of the corn rootworm could be much more environmentally friendly," says Jörg Degenhardt, a researcher involved in the project. Although the researchers were not able to develop a commercially viable crop, they showed that it is possible to genetically enhance biological pest control.

The paper published by PNAS is available at For more information, read an article released by the Max Planck Institute for Chemical Ecology at