Variability in bumblebee pollination buzzes affects the quantity of pollen released from flowers

Abstract

Buzz-pollination is a plant strategy that promotes gamete transfer by requiring a pollinator, typically bees (Hymenoptera: Apoidea), to vibrate a flower's anthers in order to extract pollen. Although buzz-pollination is widespread in angiosperms with over 20,000 species using it, little is known about the functional connection between natural variation in buzzing vibrations and the amount of pollen that can be extracted from anthers. We characterized variability in the vibrations produced by Bombus terrestris bumblebees while collecting pollen from Solanum rostratum (Solanaceae), a buzz-pollinated plant. We found substantial variation in several buzzing properties both within and among workers from a single colony. As expected, some of this variation was predicted by the physical attributes of individual bumblebees: heavier workers produced buzzes of greater amplitude. We then constructed artificial "pollination buzzes" that varied in three parameters (peak frequency, peak amplitude, and duration), and stimulated S. rostratum flowers with these synthetic buzzes to quantify the relationship between buzz properties and pollen removal. We found that greater amplitude and longer duration buzzes ejected substantially more pollen, while frequency had no directional effect and only a weak quadratic effect on the amount of pollen removed. These findings suggest that foraging bumblebees may improve pollen collection by increasing the duration or amplitude of their buzzes. Moreover, given that amplitude is positively correlated with mass, preferential foraging by heavier workers is likely to result in the largest pollen yields per bee, and this could have significant consequences for the success of a colony foraging on buzz-pollinated flowers.

Flowers with poricidal anthers and their complex interaction networks—Disentangling legitimate pollinators and illegitimate visitors

“…While buzzing flowers, these bees contact the stigma in most visits because their body size usually exceeds the gap between anthers and stigma (see Liu & Pemberton, ; Solís‐Montero & Vallejo‐Marín, ). Flower‐buzzing bees, like those of Bombini, Centridini, Euglossini and Xylocopini effectively adjust pollen‐collecting behaviour to quickly extract large amounts of pollen from poricidal anthers (Buchmann, ; Buchmann & Hurley, ; Burkart et al, ; De Luca et al, ; Renner, ; Russell, Buchmann, & Papaj, ). Almost all these bee species were network peripherals and visit flowers of a few plant species.…”

Do managed bees drive parasite spread and emergence in wild bees?

“…Bumblebees have several adaptations such as the ability to buzz pollinate (sonication) and their insulated bodies making them ideal pollinators for these plant and crop species (De Luca et al., 2013, Goulson, 2010, Heinrich, 1993, Velthuis and Van Doorn, 2006). Unlike honey bees, bumblebees do not produce honey or hive material suitable for mass market sales.…”

Assessment of pollen rewards by foraging bees

“…Studies of buzz pollination, where bees use vibrational movements to shake pollen from small pores in a flowers' anthers, show that both bumblebees and carpenter bees adjust their flower handling time according to the amount of pollen released by a flower (Buchmann & Cane ; De Luca et al . ; Burkart, Schlindwein & Lunau ), though this is not necessarily true for all flowers with poricidal anthers (Nunes‐Silva et al . ).…”