Jul 10, 2022
A new study shows plants can ‘hear’ the humming of nearby pollinators and increase their sugar content in response.
It’s a common assumption that auditory information is reserved for living things with ears and that creatures without cochlea - namely plants - can tune into sound. But a new study suggests the plants are listening, and some flowers even sweeten up their nectar when they sense a pollinator approaching, reports National Geographic
Since sound is propagated as a wave, it doesn’t always take the complex set of ear bones and hair cells found in mammal ears to detect the presence of sound, just the ability to perceive vibrations.
To test the idea, Tel Aviv University evolutionary theoretician Lilach Hadany and her team looked at the relationship between bees and flowers. The team exposed the beach evening primrose, Oenothera drummondii, to five types of sound: silence, the buzz of a bee from four inches away, and low, intermediate and high pitched sounds produced by a computer. They then measured the amount of nectar that the flowers produced after being exposed to the sound.
Blossoms exposed to silence as well as high-frequency and intermediate-frequency waves produced the baseline amount of sugar expected in their nectar. However, the blooms exposed to the bee’s buzz and low-frequency sounds bumped their sugar content up 12 to 20 percent within three minutes of being exposed to the hum. In other words, when they “heard” a bee approaching, they sweetened their nectar.
Perhaps this isn’t too surprising because - although flowers come in all shapes and sizes - so many are actually rather ear-shaped, with petals forming conical or cupped shapes.
The results of Hadany's study appears on the preprint service bioRxiv and has not yet been published in a peer-reviewed journal. However, entomologist Richard Karban from the University of California, who researches interactions between plants and insects, says the new study is legitimate, and builds on other recent research showing plants can respond to vibrations.
“The results are amazing,” he says. “They’re the most convincing data on this subject to date. They’re important in forcing the scientific community to confront its skepticism.”