Buzz pollination, floral traits and pollen release

Bumble-bee workers assort themselves among Pedicularis species according to size, adjusting their buzzing behavior in relation to the species' floral traits
Buzz pollination, floral traits and pollen release
Buzz pollination, floral traits and pollen release

The mechanism of pollen release by sonication (buzz pollination) remains poorly understood. In a comparative study of eight sympatric buzz-pollinated species of Pedicularis, Corbet and Huang find that workers of bumble-bees (Bombus friseanus) assort themselves among Pedicularis species according to body size, and adjust their buzzing behaviour (buzz/wingbeat frequency ratio) in relation to the floral traits (galea length, pollen-grain volume) of each species. A reconsideration of published experimental studies indicates that pollen release depends on the velocity component of the buzzing vibration, supporting a hypothesis that triboelectric charging of pollen grains may contribute to the mechanism.