Investigating the Mechanics of Buzz Pollination: A Structural Dynamics Perspective

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This grant will fund research that enables a better understanding of how bees extract pollen from flowers, with application to the design of artificial pollination systems for reducing costs and enhancing yields of agricultural crops that depend on dwindling numbers of natural pollinators, thereby promoting the progress of science and advancing the national prosperity and welfare. Economically valuable crops such as tomatoes, chilies, and eggplant rely for reproduction on native bee populations performing a behavior called buzz pollination, in which a bee lands on a flower stamen (male reproductive organ) and rapidly vibrates it to release its pollen. This pollen is collected on the bee’s abdomen and may be transferred to the pistil (female reproductive organ) of another flower as the bee continues to forage. While buzz pollination is critical to food security, the mechanical processes by which pollen are released by the flower are poorly understood. This knowledge gap stands in the way of the development of new technologies that may supplement natural pollinators in agricultural settings. In this project, this challenge is overcome by a systematic development of high-fidelity, data-driven models of the structural mechanics of deformable stamens and the dynamics of pollen expulsion using physical experiments and advanced computational analysis. Concurrent development of buzz pollination workshops, video, and other resources for the public will increase the accessibility of this research.This research aims to quantify the structural deformation response of floral stamens under dynamic loads induced by a bee and the subsequent expulsion of pollen due to stamen vibrations and induced aerodynamic flows. This project will provide critical insight into how the vibratory forces imparted by buzz-pollinating bees are optimized to maximize pollen release. First, experimental studies will be conducted to quantify the forces imparted by buzz-pollinating bees and to measure how floral stamens respond to such forces. Finite-element models of stamens will then be created and refined such that they accurately predict previously measured dynamic responses. Finally, computational models of pollen expulsion will be developed using the discrete-element method and moving boundary conditions prescribed from finite element modeling of the stamen. These pollen expulsion models will consider particle kinetics, adhesion, friction, and viscous aerodynamics. Pollen particle parameters will be identified via a combination of atomic force and optical microscopy. Parametric studies will reveal which physical phenomena are most critical to pollen expulsion.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.