In the pathway: Attracting pollinators
Buzz pollination
The thoracic vibration of a bumblebee that releases the pollen of certain flowers with poricidal anthers.
Explanation
Some flowers (tomato, blueberry, aubergine, nightshade) only release their pollen fully when they are vibrated, which bumblebees (Bombus) and certain solitary bees know how to do (foundational study: Buchmann 1983). Honeybees do not perform sonication effectively.
Refined definition
Buzz pollination, or sonication, is the technique by which certain pollinators (above all bumblebees of the genus Bombus) grip a flower with poricidal anthers, anthers that release their pollen only through small apical pores, and vibrate it at a frequency of about 400 Hz by rapidly contracting their flight muscles, decoupled from the wings. The pollen is ejected through the pores as if from a shaker and sticks to the insect's hairy body.
Key points
The plants that depend on it
About 8% of flowering plants have poricidal anthers requiring sonication: tomato (Solanum lycopersicum), aubergine, pepper (to a lesser degree), potato, blueberry (Vaccinium), cranberry, several wild Solanum. Source: Buchmann S.L. (1983), “Buzz pollination in angiosperms”, Handbook of Experimental Pollination Biology.
Why cultivate bumblebees
In the vegetable garden, attracting bumblebees (the buff-tailed Bombus terrestris, the common carder B. pascuorum, the garden bumblebee B. hortorum) and the other bees able to vibrate flowers can give heavier tomatoes (meta-analysis by Cooley and Vallejo-Marín, 2021); aubergine and blueberry are also among buzz-pollinated crops. Without these bees the tomato still produces thanks to the wind, sometimes with smaller fruit. How to attract them: early flowers (willow, dandelion), continuous ones (comfrey, borage, lavender), late ones (sedum, ivy).
Alternative pollinators
A few solitary bees perform sonication: carpenter bees (Xylocopa), some Anthophora, some Andrena. Honeybees (Apis mellifera) cannot do it effectively. This is the decisive argument for favouring a diversity of wild pollinators rather than a single managed species.
Watch out for
- • Kiwi: honeybees pollinate it too, but a review lists it among buzz-pollinated crops, where bumblebees and other buzzing bees are often more effective (Cooley and Vallejo-Marín, 2021).
- • In a closed greenhouse without bumblebees, tomato production drops: tapping each truss by hand with a vibrating comb can substitute (the professional “tapping” method).
Sources
- Buchmann, S.L. (1983). Buzz pollination in angiosperms. In Jones, C.E. & Little, R.J. (dir.), Handbook of Experimental Pollination Biology. New York : Scientific and Academic Editions.
- Cooley, H. & Vallejo-Marín, M. (2021). Buzz-pollinated crops: a global review and meta-analysis of the effects of supplemental bee pollination in tomato. Journal of Economic Entomology, 114(2), 505-519.
- De Luca, P.A. & Vallejo-Marín, M. (2013). What's the 'buzz' about? The ecology and evolutionary significance of buzz-pollination. Current Opinion in Plant Biology, 16(4), 429-435.