Are flowers tuned to buzzing pollinators? Variation in the natural frequency of stamens with different morphologies and its relationship to bee vibrations

Abstract

7During buzz pollination, bees use vibrations to remove pollen from flowers. Vibrations at the natural 1 8 frequency of pollen-carrying stamens are amplified through resonance, resulting in higher-amplitude 1 9

Transmission of vibrations in buzz-pollinated plant species with disparate floral morphologies

“…In buzz-pollinated flower, traits affecting vibration properties might include anther curvature (e.g. S. houstonii), stamen stiffness and length (Nunes et al, 2020). Similarly, the size of the anther locules and thickness of the anther walls may affect vibration transmission.…”

“…Although some plant substrates can act as frequency filters (Cocroft et al, 2006), frequency is not altered over the short distances involved in vibration transmission during buzz-pollination interactions . Although the natural frequency of anthers is affected by their morphology and organisation within the flower (Nunes et al, 2020), the frequency of vibrations has limited effects on pollen release in buzz-pollinated flowers, suggesting that resonance plays a minor role within the range of frequencies produced by most bees (100 to 400Hz) Nunes et al, 2020;Rosi-Denadai et al, 2020).…”

“…In some heterantherous species the two anther sets perform different functions, with long anthers contributing disproportionately to fertilisation (pollinating anthers) and short anthers (feeding anthers) being the focus of attention of buzz-pollinating bees (Luo et al, 2008;Müller, 1881;Vallejo-Marin et al, 2009). A recent study has shown that pollinating and feeding anthers of heterantherous Solanum have different natural frequencies, likely as a result of differences in biomechanical properties including size and shape (Nunes et al, 2020). Despite the potential for differences in anther and floral characteristics, such as those described above, to affect the transmission of vibrations in buzz-pollinated flowers, few studies have explicitly compared floral vibrations across disparate floral morphologies.…”

Pollen dispensing schedules in buzz-pollinated plants: Experimental comparison of species with contrasting floral morphologies

“…For example, the transmission of vibrations through the flower can alter the vibration that the anther experiences, e.g., by dampening the vibration velocity (King, 1993;Arroyo-Correa et al, 2019), which can vary between closely-related taxa (Arroyo-Correa et al, 2019). In contrast, if the bee vibrates the anther at its natural frequency (Nunes et al, 2020), resonance could amplify anther velocity and result in higher pollen removal (King & Buchmann, 1996). Joint modelling and experimental approaches to buzz pollination have the potential to help us understand the biomechanics and function of a fascinating biological interaction involving thousands of plant and bee species (Buchmann 1983;Cardinal et al, 2018).…”