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Bees, they're important and amazing creatures, and with spring on the way we thought we'd share another round of our favorite bee episodes.

Hosted by: Hank Green

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HANK: Springtime brings, you know, allergies for many of us. But also, it means the return of the cutest of the insects: the bees. They just are, don't at me. And in this compilation, we're going to share some cool facts about bees and their behavior.

From why they stare at flowers (you know, which we do as well) to why some of them... Stab plants? Is that what that says?  We're going to kick things off, though, with their buzz because bees are not the only insects that do this.

Other critters like beetles and those pesky mosquitoes, they buzz too. But some species of bees have a unique reason to produce that trademark sound - let me explain. Plenty of insects buzz when they fly around like beetles and that little [buzzing sound] of a mosquito - I hate that noise so much.

But bees are kind of special. There are more than 20,000 species of bees, all of which buzz when they fly and many of which also do it to communicate. But some bees buzz for a completely different reason that has nothing to do with communication or with flight: they're trying to get pollen out of flowers in what's known as "buzz pollination".

The kind of buzzing we hear when bees fly comes from their wings, which they can flap at up to 230 beats per second. Their quick wing movements cause air vibrations which your ear translates to sound.  The faster the wings beat, the higher the pitch. And if you've ever had the unfortunate experience of disturbing a hive, you've probably seen them buzz a little louder in agitation.

But in buzz pollination, they generate sound energy by vibrating their bodies, not their wings. They use the same muscles they'd normally use to move their wings, but kind of separate their wings from those muscles, so their bodies vibrate instead at about 400 beats per second. This full-body vibration causes the distinct buzzing sound you hear when bees are on a flower, which is a bit louder and higher-pitched than regular flying buzzing - it's actually in the tone of middle C.

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That exact middle C buzzing is like a secret passcode that unlocks pollen trapped inside flowers.

But bees don't need to do it for every kind of flower. Most flowers are like a buffet, their pollen is on the outside of the anther - the male part of the flower - and just about anyone can come take it.

But there are some flowers, like the ones on tomato and blueberry plants, that have poricidal anthers. These anthers lock the pollen inside them, with just a small pore for an opening. To get the pollen out, the bees wrap their legs around the flower, bite down on the anther for grip, and buzz.

And when they vibrate at that super high speed, the pollen bounces up and down in the tube, and when in gains enough momentum, a bunch of it explodes out and lands on the bee. Only some bees can do this, like bumblebees and a few kinds of solitary bees. Honeybees can't.

But for the record, you don't really need a bee if you want to get the pollen out. A tuning fork will do. Or if you want to get more high tech, you can get tools to vibrate the plant to the right frequency, which yes do exist, and people actually use them to pollinate their plants; although they are not as efficient as the natural method. Because when it comes to getting up close and personal with a flower, bees are definitely the experts.

So, these bees do some extra buzzing to get pollen out of flowers, but what if there weren't any bees at all to do this shaking. Is it true that we will all spiral into starvation if honeybees go extinct?

Well, here's Stephan with more on that.

STEPHAN: Albert Einstein once said that if the bees dissapeared off the face of the earth, man would only have four years left to live. And that's terrifying. I mean Albert Einstein probably didn't say that, but the idea is terrifying.

And even if you haven't heard that particular quote, you probably heard how the death of honeeybees will lead to some doomsday scenario. Like, no honeybees will mean global starvation because 70% of our crops depend on them.

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Or that all the world's flowers will vanish and the planet will become a colorless globe of death and despair.

Is it true? Not really.

Well, maybe a little. Mostly, trying to predict what will happen if honeybees go extinct, reveals just how much we need to care for other insects. Let's start with that 70% of all crops number, since that's the one we hear the most.

It seems to be a mistaken extrapolation. It's true that roughly 70% of flowering plant species are biotically pollinated, which means they need some sort of third party creature to do the pollinating for them. But that includes only around 35% of the world's food crops.

Many of the world's staples, like corn, wheat, and rice, for example, are wind pollinated, while others like tomatoes, lettuce, and beans, are self-pollinated. So tortillas, fried rice, french bread, and pasta would be fine in the advent of a bee-pocalypse. But that leaves a bunch of plants that do require pollinators that we might worry about.

Turns out that of the 100 or so crop species that dominate human diets around the globe, only 13 need pollinators. Though, another 30 are highly dependent on them. But, just because plants are pollinated by animals, doesn't mean that they need honeybees specifically.

The honeybee is just 1 of 20,000 or so species of bee, and bees aren't the only pollinators either. In fact there are close to 200,000 different species worldwide that act as pollinators, which include butterflies, flies, moths, beetles, birds, and even mammals like bats. So what would actually happen if honeybees went extinct?

Well, there would be some changes. You see the honeybee is the main human-managed pollinator. We've grown to rely on it because it's easy for us to house, transport, and control.

But it's not native to most of the places that depend on it now. Honeybees probably originated in asia around 300,000 years ago; from there they spread throughout africa and europe mostly by human hands, arriving in north america sometime in the 17th century. You could even think of them as an invasive species in some areas, because while honeybees are good for agriculture, they're not necessarily good ecologically.

They sometimes outcompete native bees which puts those other species at risk. They can also spread diseases to native bee populations, and in some places honeybees are the sole pollinator of invasive weeds; helping ensure those invaders stick around where they aren't wanted.

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They can also spread diseases to native bee populations, and in some places, Honey bees are the sole pollinator of invasive weeds, helping ensure those invaders stick around where they aren't wanted.

If honey bees disappear tomorrow, some crops would be just fine. Most US alpalfas (?~6:13) for example, is now pollinated by a solitary Leafcutter bee.

And when researchers at the Cornell University Iticha apple orchard recently ditched their Honey bee hives, they found they still got a full crop of apples thanks to native wild bees. Other experiments have also suggested wild bees could pollinate crops in the absence of Honey bees. In Florida, Bumblebees could replace honey bees on blueberry farms.

And the solitary Blue Orchard Bee, which occurs throughout most of the United States and as far north as Canada, could pollinate peaches, cherries and almonds. And the Alkali bee, another solitary species that's native to the western and south western United States could pollinate onions. As a bonus, these wild bees aren't vulnerable to colony collapse disorder.

So in many cases if Honey bees disappeared, it's likely other species could step up.  But that doesn't mean we can stop worrying about the Honey bees. Without the Honey bee some foods would become more expensive, because for many crops Honey bees are still the most important pollinator. Coffee for example doesn't need Honey bees, but their presence can significantly boost yield.

And higher yield means less expensive coffee. There are also a handful of fruit, seed, and nut crops that would have much lower yields without Honey bees. For instance Macadamia Nut Trees are up to ten times more productive when visited by Honey bees.

And it's not like we could just go like 'well the Honey bees are gone now so lets move in the Bubmblebees!' There would be a lot of logistical hurdles to get over. For starters, there's concern that native bees could be in trouble too. Because they are also vulnerable to things like climate change and pesticides.

So we have to be just as proactive about protecting native bees as we're trying to be about protecting the Honeybee. And there are other challenges too. For example, it's more difficult and expensive to maintain commercial Bumblebee hives.

In part, that's because Bumblebees don't make honey, and honey sales are important for offsetting the expense of maintaining a hive. And Bubmlebee colonies are smaller than Honeybee colonies. They average around 200 to 400 bees, while Honeybee colonies can have as many as 50,000 individuals.

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They're taking a mental image of what the flower and the surrounding area look like so they can visit it again. That doesn't explain why the bigger bees would do this more. That's a question that came up in a 2021 study published in Current Biology. In it, researchers were studying Bumblebee learning flights by offering Bumblebees fake flowers with fake nectar. And even thought the bees didn't seem to notice that the flowers and the nectar were totally fake, they did realize that some of them were more rewarding than others. The nectar in different flowers consisted of either 20 or 50 percent sugar. So some flowers were kinda 'meh' and others were a pretty good score. What was unexpected was that the bigger bees worked harder to remember the more rewarding flowers. They spent more time facing the flowers whille flying away from them on their learning flights. Meanwhile, the smaller bees didn't seem to care; in fact, they treated all flowers equally. This was surpising becauese if youre a bee and you find a really rewarding flower it seems you would want to remember it regardless of how big you are, but that doesn't seem to be the case, and it turns out a key variable is carrying capacity. Smaller bees don't forage that often, they spend more time on tasks around the nest. So when they do forage, they're limited by how far they can travel, so they tend not to be super picky. They dont bother putting all that effort into remembering super potent flowers because, well, they probably couldnt carry that much from them anyway. But larger bees can fly farther and carry more nectar back to the colony. Plus, their size means they can handle the cold better, and they have better eyesight so they can visit flowers in the morning when the light is low, and there's more nectar around. So, it may be worthwhile for them to seek out and memorize the locations of more rewarding flowers. Overall, it's not totally unexpected to see different bees in the same colony adopting different learning behaviors; but it was surprising to find that these behaviors seem to be based on size. Now the question is: how many other overlooked Bumblebee behaviors are there? Because the more we understand them, well, the more we get to marvel at how cool and complex  Bumblebees are.

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