Flower visitors, including pollinators, produce characteristic sounds through flapping wing movements during flight. These sounds may provide key information to flowering plants, potentially influencing their resource allocation to attract pollinators, thus impacting their fitness. In a new study, University of Turin’s Professor Francesca Barbero and her colleagues investigated the acoustic properties of airborne sounds generated by recording different flying visitors to snapdragon (Antirrhinum sp.) flowers in the field. Their results reveal that distinct flying behaviors, such as hovering, landing, and takeoff, produce unique acoustic signatures. Furthermore, the plants show reactions to the vibroacoustic stimuli from pollinators, suggesting potentially adaptive responses.
The recording device, the model Antirrhinum plant, and the approaching Rhodanthidium sticticum bee. Image credit: Vibrant Lab.
When pollinators visit flowers, they produce a variety of characteristic sounds, from wing flapping during hovering, to landing and takeoff.
However, these sounds are extremely small compared to other vibrations and acoustics of insect life, causing researchers to overlook these insects’ acoustic signals often related to wing and body buzzing.
Professor Barbero and co-authors studied these signals to develop noninvasive and efficient methods for monitoring pollinator communities and their influences on plant biology and ecology.
“Plant-pollinator coevolution has been studied primarily by assessing the production and perception of visual and olfactory cues, even though there is growing evidence that both insects and plants can sense and produce, or transmit, vibroacoustic signals,” Professor Barbero said.
The study authors played recordings near growing snapdragons of the buzzing sounds produced by spotted red-resin bees (Rhodanthidium sticticum) to monitor the flowers’ reactions.
They found that the sounds of the bees, which are efficient snapdragon pollinators, led the snapdragons to increase their sugar and nectar volume, and even alter their gene expression that governs sugar transport and nectar production.
The flowers’ response may be a survival and coevolution strategy, especially if the plants can affect the time pollinators spend within their flowers to increase their fidelity.
“The ability to discriminate approaching pollinators based on their distinctive vibroacoustic signals could be an adaptive strategy for plants,” Professor Barbero said.
“By replying to their proper vibroacoustic signal — for instance, an efficient pollinator’s — plants could improve their reproductive success if their responses drive modifications in pollinator behavior.”
While it’s clear that buzzing sounds can trigger plants’ responses, it’s less clear whether plant acoustics can also influence insect behavior — for example, whether sounds from plants can draw in a suitable pollinator.
“If this response from insects is confirmed, sounds could be used to treat economically relevant plants and crops, and increase their pollinators’ attraction,” Professor Barbero said.
The team is conducting ongoing analyses comparing snapdragon responses to other pollinators and nectar robbers.
“The multitude of ways plants can perceive both biotic factors — such as beneficial and harmful insects, other neighboring plants — and abiotic cues, like temperature, drought, and wind in their surroundings, is truly astonishing,” Professor Barbero said.
The researchers presented their findings May 21 at the joint 188th Meeting of the Acoustical Society of America and 25th International Congress on Acoustics (ASAICA25).
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Francesca Barbero et al. 2025. Vibroacoustic signals produced by flower visitors and their role in plant-insect interactions. ASAICA25, presentation # 3aAB1
