Buzz pollination explained

The flower's side of it

Most anthers split lengthwise and present pollen on an open surface, where any visitor can collect it and a good deal is lost to wind and to visitors that do nothing useful in return. A poricidal anther does not split. It stays closed and opens only through a small pore at the tip, holding the pollen inside like salt in a shaker.

This is a control mechanism. The plant is metering its pollen out to visitors capable of a specific behaviour, which raises the proportion delivered to another flower of the same species rather than eaten or wasted. The families that do it most are the nightshades, the heathers and blueberries, the melastomes and a scattering of others — somewhere around 20,000 species in total.

The bee's side of it

1. 1GripThe bee lands and curls around the anther cone, holding on with its mandibles and legs. This part is visible and looks like wrestling.
2. 2Decouple and vibrateIt uncouples its flight muscles from its wings and contracts them rapidly — often several hundred times a second — transmitting the vibration through its body into the anther. The wings stay largely still, which is why a buzz-pollinating bee sounds different from a flying one.
3. 3CollectPollen sprays out of the pore onto the bee's body and is groomed into the scopa or corbicula. The whole event takes a second or two, and a bee will repeat it on flower after flower.

Why honey bees cannot

Honey bees do not perform sonication. They visit poricidal flowers and collect what has already been shaken loose by other visitors or by wind, which makes them poor pollinators of these species rather than useless ones. It is the clearest single case of the honey bee not being a general-purpose substitute for wild bees.

The same fact runs through the plant lists on this site. Blueberry, cranberry and bilberry are buzz-pollinated; in Australia a large share of the native flora is; and in the Neotropics Melipona are among the significant buzz pollinators, which is one reason stingless bees matter agriculturally there.

What this means for a garden

• If you grow tomatoes, aubergines or peppers, the pollinator you need is a bumblebee or a solitary buzz pollinator — not a hive.
• Blueberries crop measurably better where wild bees are present, and a hive alone does not substitute.
• Bare undisturbed ground and undisturbed stems matter here, because the bees that do this are mostly solitary.
• Adding honey bee hives to help these crops is a common and ineffective response, and can add competition without adding the service.