A groundbreaking study from Tel Aviv University has provided the first scientific evidence of acoustic interaction between plants and insects, revealing that female moths make critical reproductive decisions based on ultrasonic sounds emitted by nearby vegetation.
The research, conducted by Professor Yossi Yovel from the School of Zoology and Professor Lilach Hadany from the School of Plant Sciences and Food Security at TAU's George S. Wise Faculty of Life Sciences, demonstrates that female moths actively avoid plants emitting distress signals when selecting locations to deposit their eggs. The study was published as a pre-print on December 27, 2024, in the journal eLife.
These ultrasonic communications occur at frequencies beyond human hearing capabilities but remain clearly audible to moths and other insects. The research team, led by students Dr. Raya Seltzer and Guy Zer Eshel in collaboration with scientists from the Plant Protection Institute at the Volcani Institute, discovered that when plants broadcast distress sounds, female moths consistently choose healthier plants that remain silent.
The investigation builds upon previous research published by the same team approximately two years ago, which initially revealed that plants under stress emit sounds at ultrasonic frequencies detectable by many animals. That initial discovery sparked worldwide interest and opened extensive research opportunities into acoustic communication between plants and animals.
"After proving in the previous study that plants produce sounds, we hypothesized that animals capable of hearing these high-frequency sounds may respond to them and make decisions accordingly," Professor Yovel explained. "Specifically, we know that many insects, which have diverse interactions with the plant world, can perceive plant sounds. We wanted to investigate whether such insects actually detect and respond to these sounds."
The researchers focused their attention on female moths due to their reproductive behavior patterns. "We chose to focus on female moths, which typically lay their eggs on plants so that the larvae can feed on them once hatched," Professor Hadany stated. "We assumed the females seek an optimal site to lay their eggs, a healthy plant that can properly nourish the larvae."
The scientific team questioned whether moths would heed warning signals from stressed plants. "When the plant signals that it is dehydrated and under stress, would the moths heed the warning and avoid laying eggs on it? To explore this question, we conducted several experiments," Professor Hadany added.
The first experiment aimed to separate the auditory component from other plant characteristics such as color and scent. Researchers presented female moths with two boxes – one containing a speaker playing recordings of tomato plants in dehydration states, while the other remained silent. The moths demonstrated a clear preference for the "noisy" box, which they likely interpreted as a living plant, even if the plant was experiencing stress.
The research team concluded that moths indeed perceive and respond to the playback of plant-emitted sounds. When researchers neutralized the moths' hearing organs, this preference disappeared, and they chose both boxes equally, providing clear evidence that the preference was specifically based on listening to sounds, not on other stimuli.
The second experiment presented female moths with two healthy tomato plants – one equipped with a speaker playing sounds of a drying plant, and one that remained silent. Again, they showed clear preference, but this time for the silent plant, from which no distress sounds were heard, and probably serving as a better site for laying eggs.
A final experiment presented moths with two boxes again – one silent and the other containing male moths, which also emit ultrasonic sounds at frequencies similar to plant sounds. This time, the females showed no preference and laid their eggs equally in both boxes. The researchers concluded that when deciding where to lay their eggs, the females specifically respond to plant-emitted sounds and not to the sounds made by males.
"In this study, we revealed the first evidence for acoustic interaction between a plant and an insect," the researchers conclude. "We are convinced, however, that this is just the beginning. Acoustic interaction between plants and animals doubtlessly has many more forms and a wide range of roles. This is a vast, unexplored field, an entire world waiting to be discovered."
