Most flowering plants are more than willing to spread their pollen around. But some flowers hold out for just the right partner. Bumblebees and other buzz pollinators know just how to handle these stubborn flowers. They vibrate the blooms, shaking them until they give up the nutritious pollen.
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In the summertime, the air is thick with the low humming of bees delivering pollen from one flower to the next. If you listen closely, a louder buzz may catch your ear.
This sound is the key to a secret stash of pollen that some flowers hide deep within their anthers, the male parts of the plant. Only pollinators that buzz in just the right way can vibrate tiny grains out of minuscule holes at the top of the anthers for a protein-rich snack.
The strategy, called buzz-pollination, is risky. But it’s also critical to human agriculture. Tomatoes, potatoes and eggplants need wild populations of buzz pollinators, such as bumblebees, to produce fruit. Honeybees can’t do it.
Plants need a way to get the pollen — basically sperm — to the female parts of another flower. Most plants lure animal pollinators to spread these male gametes by producing sugary nectar. The bee laps up the sweet reward, is dusted with pollen and passively delivers it to the next bloom.
In contrast, buzz-pollinated flowers encourage bees to eat the pollen directly and hope some grains will make it to another flower. The evolutionary strategy is baffling to scientists.
“The flower is almost like playing hard to get,” says Anne Leonard, a biologist at the University of Nevada, Reno who studies buzz pollination. “It’s intriguing because these buzz-pollinated plants ask for a huge energy investment from the bees, but don’t give much back.”
--- What is buzz pollination?
Most flowering plants use sugary nectar as bait to attract bees and other pollinators, which get coated in pollen along the way. And since bees are messy, they inadvertently scatter some of that pollen onto the female part of the next flower they visit.
But some flowers lock their pollen up in their anthers, the male parts of the flower, instead of giving it away freely. The only way for the pollen to escape is through small holes called pores. Some pollinators like bumblebees (but not honeybees) are able to vibrate the flower’s anthers which shakes up the pollen and causes it to spew out of the pores.
The bumblebee collects the pollen and uses it as a reliable and protected source of protein.
--- What important crops use buzz pollination to make food?
The most important crops that use buzz pollination are potatoes, tomatoes, pumpkins, eggplants, cranberries and blueberries
--- What animals are capable of buzz pollination?
Many types of bees engage in buzz pollination, also called sonication. The most common is probably the bumblebee. Honeybees generally don’t use buzz pollination.
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Anne Leonard Lab, University of Nevada, Reno | Department of Biology
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