Israeli researchers have discovered that female moths decide where to lay their eggs based on ultrasonic sounds emitted by tomato plants, providing evidence that plants and animals can interact through sound, Tel Aviv University said in a statement on Tuesday.

In a previous study, the team discovered that plants under stress, such as dehydration, emit ultrasonic sounds that are beyond human hearing but can be detected by many animals. In the new study, the researchers explored whether insects detect and respond to these sounds.

They focused on moths, which lay eggs on plants to let their larvae feed after hatching. The team wanted to know whether moths avoid laying eggs on plants that emit distress sounds.

In one experiment, female moths were placed between two boxes, isolating the auditory factors from other plant characteristics such as color and scent. One had a speaker playing recorded ultrasonic sounds of dehydrated tomato plants, while the other was silent.

The moths preferred the box with sound, which suggests they interpreted the ultrasonic sound as the presence of a living plant, even if it was under stress. When their hearing organs were blocked, they no longer showed a preference for either. Researchers said this confirmed that they were responding to the ultrasonic sound alone.

In another test, the moths had to choose between two healthy tomato plants, with one near a speaker playing the ultrasonic sound from a distressed plant and the other silent. This time, the moth chose the silent plant, suggesting they avoid stressed plants when real options are available.

In a final test, moths were offered a choice between a silent box and one containing male moths, which also produce similar ultrasonic sounds. The females showed no preference, laying their eggs in both boxes.

The researchers explained that, when deciding where to lay their eggs, female moths respond specifically to plant-emitted sounds rather than to similar sounds made by males.

The findings were published in the journal eLife. The researchers said that acoustic interaction between plants and animals exists in many more forms and serves a wide range of roles. Their study is just the beginning of uncovering how plants and animals interact through sound in nature.

(Cover: A small emperor moth. /VCG)