New York, May 22 (IANS): Vegetarians please note! Next time when you chew upon your favourite lettuce, be a little more considerate.

According to researchers from the University of Missouri (MU), plants can identify the sound of themselves being eaten and react to the threat.

The team found that plants responded to the sounds that caterpillars make when eating and responded with more defences.

They release more mustard oils which are unappealing to caterpillars and thus ward them off, Daily Mail reported citing the study.

But plants did not defend against the wind despite it having a similar acoustic sound.

In the study, caterpillars were placed on Arabidopsis, a small flowering plant related to cabbage and mustard.

Using a laser, researchers were able to measure the movement of the leaf in response to the chewing caterpillar.

"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 defences," explained lead researcher Rex Cocroft from the University of Missouri.

Caterpillars react to this chemical defence by crawling away, "so using vibrations to enhance plant defences could be useful to agriculture, added co-author Heidi Appel, senior research scientist at MU.

The team will further research how vibrations are sensed by plants, what features of the vibrational signal are important and how the mechanical vibrations interact with other forms of plant information to generate protective responses to pests.

The study appeared in the journal Oecologia.