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Plants have feelings too. Past studies revealed that sound, wind and touch could all affect plant growth. However, new research reveals that plants can also combine sensory data to detect potential threats.

Researchers at the University of Missouri-Columbia found that the sound of caterpillars munching on leaves triggers nearby plants to react with more defense mechanisms.

"Previous research has investigated how plants respond to acoustic energy, including music," senior researcher Heidi Appel, a scientist in the Division of Plant Sciences in the College of Agriculture, Food and Natural Resources and the Bond Life Sciences Center at University of Missouri-Columbia, said in a news release. "However, our work is the first example of how plants respond to an ecologically relevant vibration. We found that feeding vibrations signal changes in the plant cells' metabolism, creating more defensive chemicals that can repel attacks from caterpillars."

After comparing plants that were played recordings of caterpillar feeding vibrations to those that experienced silence, Appel and his team found that plants previously exposed to feeding vibrations fought harder by producing more caterpillar-repellent mustard oils.

"What is remarkable is that the plants exposed to different vibrations, including those made by a gentle wind or different insect sounds that share some acoustic features with caterpillar feeding vibrations did not increase their chemical defenses," Cocroft said. "This indicates that the plants are able to distinguish feeding vibrations from other common sources of environmental vibration."

"Plants have many ways to detect insect attack, but feeding vibrations are likely the fastest way for distant parts of the plant to perceive the attack and begin to increase their defenses," Cocroft said.

"Caterpillars react to this chemical defense by crawling away, so using vibrations to enhance plant defenses could be useful to agriculture," Appel said. "This research also opens the window of plant behavior a little wider, showing that plants have many of the same responses to outside influences that animals do, even though the responses look different."

The findings were published in the journal Oecologia.