Buzz Pollination

by on June 11, 2008

Bumblebee. Photo Courtesy Agricultural Research Service.

Bumblebee.

Photo Courtesy Agricultural Research Service.

Bumblebees and other native bees were long ignored by farmers because they produce little or no honey and don’t form large, portable colonies like honeybees do.

But the true importance of bees is their ability to pollinate plants, that is, to perform the essential task of transferring pollen from plants’ male to female reproductive organs, staring the process of fruit and seed formation.  Bumblebees are now being heralded as important crop pollinators, especially in these times of declining honeybee populations.  And bumblebees are especially effective pollinators because they, as well as some other native bees, can employ a method not practiced by honeybees, called “sonication” or “buzz pollination.”

Buzz pollination can be useful for releasing or collecting pollen from many types of flowers, but it is essential for some, including tomatoes, blueberries, and our native manzanitas.  The anthers (male reproductive organs) of these flowers have only small pores through which pollen is released, like the holes in a pepper shaker.  Sometimes wind or visits from insects can inadvertently shake out some pollen, but the amounts are small.  Also, many of these flowers do not produce nectar, so honeybees ignore them anyway.

Bumblebees, by contrast, actively collect and eat not just nectar but also protein-rich pollen.  And a bumblebee can cause a flower to discharge a visible cloud of pollen through buzz pollination.  The bumblebee grasps the flower with its legs or mouthparts and vibrates its flight muscles very rapidly without moving its wings.  This vibration shakes electrostatically charged pollen out of the anthers, and the pollen is attracted to the bumblebee’s oppositely charged body hairs. The bumblebee later grooms the pollen from its body into pollen-carrying structures on its back legs for transport to its nest.

Sometimes bumblebees employ buzz pollination on flowers that don’t require it, for example, California poppies.  This may release the already accessible pollen more quickly and efficiently.  They also use the energy of buzz pollination for other purposes, for example, compacting soil in their underground burrows (bumblebees don’t build hives like honeybees) or moving a pebble or other obstacle.

Honeybees cannot perform buzz pollination (so far, only a few kinds bees are known to do it), and therefore they cannot pollinate some important crops and wild plants.  In fact, commercially-grown greenhouse tomatoes were traditionally pollinated by handheld electric vibrators with names like “Electric Bee” or “Pollinator II.”

Although discovered relatively recently, buzz pollination is no secret.  Buzz-pollinating bumblebees make a distinctive, middle-C buzz, which is noticeably higher pitched than the buzz of flight.  No special equipment is needed to hear the sound of buzz pollination, just listen for a distinctive middle-C “raspberry” next time you find a plant buzzing with bumblebees.

See more articles in: Plants and Fungi

5 comments:

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DONNA BENTKOWSKI on June 6th, 2015 at 11:55 am

I have tomato plants under row cover to prevent pest damage,can i just shake my cages several times a day to release a cloud of pollen or do i have to uncover my cages and let bumble bees perform buzz pollination? In other words would shaking the cages be as effective as letting the bees do the job? yes,no? or at least work well enough that i would get enough fruit that it would be worth the benefit of covering my plants for pest prevention?Yes,No?
If i have to use bees to buzz pollinate my plants and therefore uncover my plants ,for how long would i have to uncover them and what time of day would be the best time to uncover my plants for the most bees to be present to buzz pollinate my tomatoes?
Peppers and eggplant are also pollinated by buzz pollination as well ,correct?Yes,No?
Could i shake their cages as well?Yes,No?
You mention commercially-grown greenhouse tomatoes were traditionally pollinated by handheld electric vibrators with names like “Electric Bee” or “Pollinator II.”Are commercially-grown greenhouse tomatoes still being pollinated today by handheld electric vibrators with names like “Electric Bee” or “Pollinator II. Could shaking the cages be as effective as using handheld electric vibrators with names like “Electric Bee” or “Pollinator II. that ” commercially-grown greenhouse tomato growers have or continue to use today?Yes,No?

DONNA BENTKOWSKI on June 6th, 2015 at 12:02 pm

Has anyone ever used a“Electric Bee” or “Pollinator II” to pollinate their tomatoes,peppers or and eggplants and if so where did u buy one?

Sue Rosenthal on June 8th, 2015 at 12:13 pm

Hi Donna,
Thank you for reading the article! I wish I could answer your questions (great questions!), but I don’t know anything about intentional pollination of crops. I wrote the article about buzz pollination from a nature perspective; the brief mechanical pollinator info was in there for fun.
You might be able to get good information about pollinating tomatoes under row covers from the University of California Cooperative Extension’s Agriculture and Natural Resources Division: http://ucanr.edu/About_ANR/What_is_ANR/. There are offices in all the counties of California, with Master Gardeners and others who answer questions.
I hope you find the information you need!
Sincerely,
Sue

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