For the past few years, my lab has been studying buzz pollination, a floral mechanism in which bees use vibrations to extract pollen from flowers. During buzz pollination, bees use their thoracic muscles to produce very high frequency vibrations (hundreds of cycles per second). These vibrations cause pollen (carrying the plant’s male gametes) to bounce inside the anthers and eventually be forcefully propelled outside the anther and onto the bee’s body.
Buzz pollination has evolved among thousands of flowering plants, including species of agricultural importance like tomatoes and potatoes. The reliance of many plant species on buzz-pollinating bees makes particularly worrying the recent decline in bee populations around the world.
Interestingly, not all bees can buzz-pollinate: Honeybees have never been observed using vibrations to remove pollen from flowers, which is odd given that they can produce vibrations in other contexts.
Buzz pollination is relatively well known (many people have heard bumblebees buzzing away while extracting pollen), yet there are many open research questions in this field. For the past years we have used simple experiments and lots of patience to extract some of the secrets of this fascinating buzz-pollinating mechanism.
A couple of years ago, my colleague Paul de Luca and I published a review of buzz pollination in Current Opinion in Plant Biology. Our review paper attracted the attention of the press, and we were lucky to have our work covered by Carl Zimmer in this New York Times article.
Bees can learn to buzz-pollinate
We have recently published an article showing for the first time that bees can adjust the type of vibrations they produce as they gain experience at manipulating flowers. The work was started as the dissertation of one of my undergraduate students, Tan Morgan, and in collaboration with Penelope Whitehorn and Gillian Vallejo. You can read more about this recent work and its implications here.
Vibrations produced during defence are different from those produced while feeding
Last year we published an article showing that bees can adjust the type of vibrations depending on the context. Thus, and angry buzz has a different acoustic signature than a buzz produced during feeding. The fact that not all buzzes are equal (see coverage in The Economist), together with the observation that different bee species have characteristic acoustic signals, raises the interesting possibility that bees can adjust the type of vibration produced to maximise pollen release. It has been previously suggested that bees may be “tuned in” with the flowers they visit.
Ecology and Evolution of buzz pollination
We are about to start a new, exciting project thanks to the generous funding of the Leverhulme Trust. Our project seeks to integrate flower and bee perspctives to understand how buzz pollination works. We want to figure out how flower traits affect their reponse to vibrations, and how bee morphology and behaviour change their capacity to produce different types of vibrations. We will use a variety of approaches from bio mechanical analyses in the lab to ecological experiments in the field. Stay tuned for updates!