Collecting pollen can be as exhausting for bees as flight take-off, according to a new study from the University of Sussex. The research, published by the Royal Society, is the first to directly measure the energy cost of floral sonication, or 'buzz pollination'—where bees vibrate flowers to extract pollen.
Energy Demands of Floral Buzzing
Scientists found that the vibrations bumblebees use to shake pollen loose from flowers are among the most exhausting behaviours they perform. A single buzzing event requires about the same amount of energy as a flight take-off. Because buzzing can last longer, the total drain on energy can be even greater.
Natacha Rossi, a University of Sussex research fellow who led the study, said: 'As nectar availability shifts due to climate change or habitat loss, the energetic demands of pollination could influence bee behaviour and, ultimately, where bees forage and which plants they pollinate. These results help us to better understand plant-pollinator relationships and just how hard at work a buzzing bee really is.'
Metabolic Rate and Energy Budget
The metabolic rate of a floral buzzing bee is more than 30 times higher than its resting metabolism, making the process among its most energetically demanding behaviours. The research challenges the common assumption that flight dominates bee energy budgets.
Dr Beth Nicholls, principal research fellow at the University of Sussex, said: 'The findings suggest that floral buzzing could represent a major part of a bee's daily energy budget, something that has previously been overlooked. These bees must carefully choose which flowers they visit to ensure they have enough energy to pollinate.'
Declining Bee Populations
In 2024, the number of bumblebees in the UK declined by almost a quarter compared with the 2010-2023 average, according to the Bumblebee Conservation Trust. Researchers attribute the drop to cold and wet conditions that spring. Despite a rebound in 2025, many species remain below average numbers.
Prof Mario Vallejo-Marin, at Uppsala University, said: 'We long suspected that buzz pollination was an energetically expensive affair. We can now put a number to it and begin making quantitative predictions of how it could affect the ecology and evolution of bees and buzz-pollinated flowers.'
Two-Phase Energy Drain
The study notes that the energetic drain does not stop when pollination stops. After buzzing, bees enter a 'grooming and pollen-packing phase', which takes even more energy. They then must force a high-power take-off to carry their heavier load away, making the entire process a demanding two-phase sequence.
Researchers warn that declining nectar supplies caused by climate crisis and habitat destruction could intensify the strain on pollinators, potentially forcing bees to make difficult choices about which flowers to visit.
