A groundbreaking study conducted by Tel Aviv University in Israel has revealed for the first time that insects can hear the sounds emitted by plants and make decisions based on them. This discovery opens up a new realm in the study of sound communication in nature and could potentially change the way people understand agriculture and pest management.
The research team, led by zoologist Yossi Yovel and botanist Lilach Hadany, had previously demonstrated that plants emit ultrasonic “clicking sounds” similar to popping popcorn under stress conditions such as soil dryness, with frequencies far beyond the range audible to the human ear. A healthy tomato plant emits sound on average only once per hour, but under drought stress, it may burst out dozens of times per hour.
So, who is listening to these sounds? Researchers suspect that insects could be potential “listeners” and conducted a series of experiments focusing on female African cotton leafworms (Spodoptera littoralis). These moths typically lay eggs on tomato plants for their larvae to feed on.
The research findings include:
– Between two tomato plants, one healthy and one water-stressed, the moths significantly preferred laying their eggs on the “quiet, healthy” plant.
– When plants were not present in the experiment but only recordings of sounds produced by stressed plants were played, the moths chose to lay eggs near the side playing the sound, indicating they perceive sound as a clue to the presence of plants.
– When moths could not hear the plant sounds, they no longer exhibited a preference for egg-laying, demonstrating that sound serves as their decision-making basis.
– If both sides had healthy plants but one side played sounds of stressed plants, the moths again favored choosing the quiet side, possibly utilizing olfactory cues as well.
Researchers emphasize that these plant sounds may not necessarily be signals for communicating with insects but rather passive “cues”. In other words, plants do not “intentionally” produce sounds to attract or repel insects, but insects can hear and utilize them, leading to an “acoustic interaction”.
The final conclusion of the study states: “We have revealed evidence of sound interaction between plants and insects for the first time. We believe this is just the beginning, as there are certainly more diverse forms and roles of sound interaction between animals and plants in nature waiting to be explored.”
The study was published on Tuesday, July 15, in the journal “eLife”, and was a collaborative effort between Tel Aviv University, and the Volcani Institute, a division of the Israeli Ministry of Agriculture.