Research Shows Caterpillars Trick Corn Plants to Lower their Defenses

Chemical ecologists in Pennsylvania State University have uncovered a deception that has likely evolved over a thousand years. They found that caterpillars have tricked corn plants by defecating on crevasses where the leaves meet the stalks. Large amounts of frass accumulate in the structures and remain there for a long period of time.

According to Dawn Luthe, professor of plant stress biology, the caterpillar frass tricks the plant into sensing that it is being attacked by fungal pathogens, and mounting a defense against them, suppressing the plant's defenses against herbivores. Plants cannot defend against pathogens and insect attackers simultaneously, and need to switch on either their pathway to defend against herbivores or their pathway to defend against pathogens.

The research may lead to plants genetically modified to incorporate the proteins from the frass to boost a crop's native resistance to pathogens. Caterpillar frass is composed of molecules derived from the host plant, the insect itself, and associated microbes, and hence it provides abundant cues that may alter plant defense responses, explained lead researcher Swayamjit Ray.

For more information, read the news release at the Penn State website.