What is pollination?
Pollination is the movement of pollen from the anthers (male part of a flower) to the stigma (female part of a flower).
Pollen is the sperm of the flowering plant world. It fertilizes a flower’s egg cells so that the plant can produce seeds and fruits. When seeds germinate, a new plant (the offspring) grows.
Some flowers self-pollinate (pollen moves to a flower on the same plant, perhaps even the same flower where it was produced). However, many others must receive pollen from a different plant. This is called cross-pollination. Such plants cannot produce seeds without pollen from another plant. This often requires a little help.
Animals, such as bees, birds, bats, butterflies, and beetles, are responsible for about 80% of the movement of pollen from flower to flower. Aptly, they are called pollinators. Wind and water also play a role.
Pollinators are critical to life on Earth. More than 1,000 plants that we consume or use to make fibers and medicines are pollinated by animals.
Fruits, vegetables, and grains are all dependent on animal pollination. Without them, we could kiss goodbye to chocolate, coffee, and tequila, along with many other essentials like apples, potatoes, and tomatoes.
In the United States, insect pollination accounts for around $40 billion in products annually. Not only are they responsible for much of our food production, but plants that require active pollination help to keep the air clean, produce oxygen, stabilize soil to reduce erosion, and provide food and shelter to wildlife.
The process of pollination
So, how does pollination work?
In typical animal-mediated pollination, pollen grains get stuck on the animal’s body while it is foraging for nectar and/or pollen on the plant. When the animal moves on to another flower, some of the pollen falls off onto the stigma.
Insects pollinate flowers when they perch on or hover around a flower and use their proboscis (tongue) to reach into the flower to suck out the nectar. Some insects (e.g., bumble bees, honey bees) intentionally collect pollen and stash some in a structure on their hind legs called a corbicula, or pollen basket. However, not all of the pollen makes it to the basket and some falls off in the next flower they visit.
What makes bumble bee pollination special?
So, do bumble bees pollinate?
Yes, they do. In fact, bumble bees are extremely important pollinators, more so for some plant species than the more famous honey bees.
But don’t feel too bad for honey bees. They are also very important for worldwide pollination and they have their own special role to play.
Another question you might have is do bumble bees make honey?
No, that’s the honey bees’ big contribution. If you’re out looking for bumblebee honey, you’ll go home disappointed. The over 250 species of bumble bees (nearly 50 of which live in the United States alone) instead serve as pollinators for a wide variety of important plants. There is great diversity in proboscis length in bumble bees, which means a correspondingly great diversity in plants that bumble bees can pollinate. Contrast that with the fewer than 10 species of honey bees.
Bumble bees are also active both earlier and later in the year and day than other bee species, emerging as early as February and dying off as late as November. They also fly in poor weather, such as cloudy, cool, and/or rainy days when other bees are stuck at home.
Keep in mind!
These distinctions are important because they mean that bumble bees are out pollinating flowers at times when other bees are not. They are able to be active in adverse conditions because they can actively thermoregulate by shivering. This produces heat in their thorax, allowing them to fly even when it’s cold out.
Furthermore, bumble bees can pollinate some flowers that other insects cannot. They do this through a process called “buzz pollution”. Some flowers are difficult to pollinate because their pollen is tightly stuck to their anthers. So, bumble bees grab onto the flower with their mouths and beat their wings very rapidly (over 130 beats per second). This vibration dislodges the pollen. Such important food crops as tomatoes, peppers, eggplants, potatoes, strawberries, blueberries, cranberries, and kiwis require buzz pollination.
Pollination is absolutely critical for natural ecosystems and agriculture. The world would be a much different place without pollinators. Bumble bees are one of the world’s top pollinators because they are a diverse group that are active when many other pollinators are not and that pollinate some plants that other pollinators simply can’t. Here, we’ve explained pollination and its importance, how it’s done, and why bumblebee pollination is especially unique.