Army worm poop deceives corn plants

Monday, December 7, 2015

Chemical ecologists at Pennsylvania State University have determined that "frass," the defecations of herbivorous caterpillars that collects in the whorls of corn leaves, tricks plants into thinking they are being attacked by a fungus infection. The plants mount a defence against such, thereby reducing their defences against the actual creatures that are attacking them. They can't defend against both fungus and insects at the same time, says Dawn Luthe, professor of plant stress biology in a Penn State newsletter published in September.

The newsletter notes that fall army worms "are voracious feeders on leaves in the confined whorls of corn plants."

The study was published in the Journal of Chemical Ecology and may lead to the isolation of specific components of the frass that can be incorporated into a compound that can be spread on crops to increase resistance to fungal attacks. That would be an "ecologically sustainable" pesticide. An alternative is a genetic modification to incorporate proteins from the frass to boost a crop's "native resistance" to pathogens.

Scientists are still trying to find a solution to dealing with those hungry army caterpillars. The faking frass is an ecological strategy "that has been perfected over thousands of years of evolution," says lead researcher Swayamjit Ray, a doctoral student at Penn State. The U.S. Department of Agriculture financed the research. BF