To see whether predator noises would affect plants, two University of Missouri researchers exposed one set of plants to a recording of caterpillars eating leaves, and kept another set of plants in silence. Later, when caterpillars fed on the plants, the set that had been exposed to the eating noises produced more of a caterpillar-repelling chemical.
Evidently, the chomping noises primed the plant to produce the deterrent. “So when the attack finally happens, it’s kaboom,” said Heidi Appel, a chemical ecologist and an author of the study. The chemical comes “faster and often in greater amounts.”
Plants exposed to other vibrations, like the sound of wind or different insects, did not produce more of the chemical, suggesting they could tell the difference between predator noises and atmospheric ones. The researchers published their work in the journal Oecologia.
Previous research on plants and sounds have found that two genes in rice switch on in response to music and clear tones, and that corn roots will lean toward vibrations of a specific frequency. (Research from the 1970s suggesting that plants prefer classical to rock music has largely been dismissed.)
--Douglas Quenqua, NYT, on plant senses