For the first time, a scientific study has shown that insects make decisions based on sounds made by plants. Researchers: This is a first step towards understanding a whole world of vocal communication in plants * Female moths preferred healthy plants that did not make distress sounds at ultrasonic frequencies that the human ear cannot hear
A scientific breakthrough by Tel Aviv University: A first-of-its-kind study in the world has shown a connection between animals and the sounds made by plants. As part of the study, the research team focused on female moths (an insect from the order Lepidoptera) and found that they make a critical decision – where to lay their eggs – based on sounds made by plants in their environment.
When the plants made distress sounds, the female moths preferred healthy plants that did not make distress sounds. These are ultrasonic frequencies that the human ear cannot hear but moths can.
The research was carried out in the laboratories of Prof. Yossi Yuval's Faculty of Life Sciences. from the School of Zoology and Prof. Lilach Hadani from the School of Plant Sciences and Food Security at Tel Aviv University, led by students Dr. Raya Seltzer and Guy Zer Eshel and in collaboration with researchers from the Plant Protection Institute at the Volcani Institute. The article was published in the journal eLife.
This study is a follow-up to the sensational discovery that the same researchers published about two years ago, which caused a lot of buzz around the world, according to which plants in distress make sounds - at a frequency that is above the hearing range of the human ear (ultrasound frequency), but is picked up by many animals. The researchers: "The discovery opened the door to extensive research on communication between plants and animals, and in the current study we began to examine the issue."
Prof. Yuval explains: "After proving in a previous study that plants make sounds, we estimated that animals that are able to hear the high-frequency sounds made by plants may respond to these sounds and make decisions accordingly. Specifically, we know that many insects, which have diverse interactions with the plant world, are able to perceive the sounds of plants, and therefore we wanted to examine whether they indeed notice the sounds and respond to them."
Private conversations between moths and tomatoes
Prof. Hadani: "We chose to focus on female moths, which usually lay their eggs on plants, so that they will serve as food for the larvae after they hatch. We assumed that the females are looking for an optimal laying site, on a healthy plant that can nourish the larvae well. So, when a plant announces with its voice that it is drying out and in distress - will they heed the warning and refrain from laying on it? To test this, we conducted a number of experiments."
In the first experiment, the researchers sought to isolate the sound component from other plant features, such as color and smell, so they presented the female moths with two boxes. One box contained a speaker that played recordings of tomato plants in a dehydrated state, while the other remained silent. The females showed a clear preference for the 'noisy' box, which to them was probably a living plant (even if in distress). The conclusion: The moths do indeed perceive and respond to sounds made by plants.
Later, when the researchers neutralized the females' auditory organ, the preference disappeared and they chose both boxes equally – evidence that the preference is based specifically on listening to sounds, and not on other stimuli.
In the second experiment, the females were presented with two healthy tomato plants – one with a speaker that made sounds of a drying plant, and one that was silent. Again, they showed a clear preference – but this time for the silent plant, which does not emit distress sounds and therefore probably serves as a better laying site.
In another experiment, the females were again presented with two boxes – one silent and the other with male moths, which also make ultrasonic sounds at a frequency similar to the plants. This time, the females showed no preference and laid eggs in both boxes equally. From this, the researchers concluded that when deciding where to lay their eggs, they respond specifically to the sounds made by the plants – and not to the sounds of males, for example.
The researchers conclude: "In this study, we have uncovered the first evidence of vocal interaction between a plant and an insect. However, we are convinced that this is only the beginning. Vocal interaction between plants and animals certainly has many more forms, and a wide variety of functions. This is a vast and open field of research, a whole world just waiting to be discovered."
for the scientific article
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