♪Intro♪
Now, I'm not a huge fan of pain, but it IS super important, biologically speaking.
It's how your body tells your brain something is wrong—that you've put your hand on
a hot stove or broken your leg.
It's such a strong signal that lots of animals have evolved to hijack it, and one group is
especially notorious for that: the insects in the order Hymenoptera: ants, bees and wasps.
Many of them are armed with venom that causes intense agony, and studying the compounds
in those venoms can teach us a lot about how pain works.
But to study their venom, you have to brave the bugs.
Which is where entomologists like Justin Schmidt come in.
Since 1984, he's catalogued the stings he's received — from over 80 different species
— on a pain scale he calls the Schmidt Pain Index.
It goes from 1 to 4, with 1 being mildly annoying and 4 being agonizing torture.
Of course, his ratings are just one person's experience.
But they line up with what we know from research into these insects' venoms, as well as what
other people say about their stings.
And they're probably as close as we're gonna get to a scientific comparison of the
pain.
So, here are some of the worst stingers Schmidt has encountered, and the biochemistry behind
why they're so awful.
Welcome to SciShow List Show: Agony Edition.
The term "fire ant" can refer to a few members of the genus Solenopsis.
But most of the time, people in the US are talking about the red imported fire ant—Solenopsis
invicta.
Native to Central and South America, red imported fire ants have invaded around the world.
They're incredibly aggressive as a species, and have potent stings that help them win
battles with native ants.
They're also known to kill baby bunnies and hatchling sea turtles and other adorable
small animals.
In terms of pain, individual fire ant stings are pretty mild.
Schmidt only rates them a 1, and describes them as "Sharp, sudden, mildly alarming.
Like walking across a shag carpet and reaching for the light switch."
But you're rarely stung by a single fire ant.
Just ask anyone who's accidentally sat on one of their nest mounds, or made the mistake
of touching a floating raft.
That's right, I said raft!
These ants survive floods by linking their waxy bodies together around their queen.
The rafts can contain 100,000 living, squirming ants looking for the first solid thing they
can find.
If that solid thing is your leg — or your butt — you can be stung by hundreds of ants
in a matter of seconds.
More than 90% of their venom is made up of alkaloids, which are organic, or carbon-containing
compounds, that also have nitrogen in them.
The specific toxins in fire ant venom are chemically similar to piperidine, the compound
that makes pepper peppery.
And there's a good reason people don't generally inject essence of pepper into their
bodies: it triggers the release of immune signaling molecules, causing burning, itching
pain and a fluid-filled pustule.
And while each individual sting might be a "1," the combined pain of hundreds is
anything but "mildly alarming."
Then there's the beloved honey bee, Apis mellifera.
Everyone's favorite pollinator.
And probably the sting most people have felt for themselves, because they're found basically
everywhere.
While they don't have the most painful stings on the planet, they can be deadly.
In fact, in Europe, North America, and even Australia, bees are deadlier than just about
any other venomous animals.
That's because in those places, allergic reactions to bee stings claim far more lives
than snakes, scorpions, and spiders combined.
And the sting ruins the bee's day, too.
Their stingers are covered in small barbs, so when the bee tries to leave, the stinger
and attached venom gland tissue stay behind.
This kills the bee.
According to Schmidt, the pain from a bee sting is only a 2.
He says it's "Burning, corrosive, but you can handle it."
I guess, assuming you're not allergic to it.
The burning sensation comes from melittin, which is a peptide — basically a small protein—
that makes up 40-60% of the venom by weight.
Melittin turns on the same pain receptors as heat, so from the perspective of our neurons,
it literally burns.
In that way, it's similar to capsaicin, which gives hot peppers their heat.
Both will cause intense pain and inflammation when injected under the skin.
We know, because scientists have done this to people who for some reason volunteered
to be injected.
For science.
There are lots of different wasps people call "yellow jackets," usually in the genus
Vespula, and they're all social, predatory wasps.
Like bees, they're some of the most common insects people get stung by all over the world,
which is why they made this list.
Also like bees, yellow jackets also get a mere 2 from Schmidt.
He describes it as "Hot and smoky, almost irreverent."
Which, I don't know what yellow jackets he's been stung by, but maybe they should
get a room.
Unlike bees, though, yellow jacket stingers are smooth, which means they can sting over
and over and over again.
By weight, more than 90% of their venom is made up of amines, a type of organic compound
related to ammonia.
Specifically, it'll often contain histamine, the same stuff that's released when you
have an allergic reaction, and serotonin, which is a neurotransmitter involved in things
like regulating your mood.
Both compounds are used by your immune cells to trigger inflammation, and receptors for
them are important parts of your body's pain system.
So it makes sense that injecting them into your skin and muscles would hurt.
The amount of histamine or serotonin in the venom depends on the species.
Eastern yellow jacket venom is 99.4% histamine, while German yellowjacket venom is 98% serotonin.
Both hurt like the dickens, but are weaksauce compared to the rest of the stings on this
list.
Harvester ants get their name from their habit of dragging seeds underground, which they
store in large caverns called granaries.
They're native to the southwestern US, and if you've never seen one that's probably
for the best: their stings earn a 3 from Schmidt.
He calls them "Bold and unrelenting," like "Somebody is using a power drill to
excavate your ingrown toenail."
We don't have a whole lot of information on how their venom works, but Schmidt thinks
the most likely pain-inducer is a small peptide in their venom called barbatolysin.
Barbatolysin acts a lot like melittin in the body, but it's much more effective at killing
cells, which might explain why stings from these ants hurt more than bee stings.
Harvester ant venoms are also surprisingly lethal — for the species with the most potent
venom, just 0.12 milligrams per kilogram of body weight is enough to kill 50% of the animals
injected with it.
Drop for drop, that's comparable to deadly snakes like cobras.
In theory, less than 10 milligrams of the stuff would probably kill the average person.
Luckily for us, these ants are pretty small, so they only inject tiny amounts of venom
at a time — at most about 25 micrograms, or thousandths of a milligram.
So it would take several hundred stings to even come close to a potentially-lethal dose.
The red-headed paper wasp is found in Central and South America.
As its name suggests, it's got a red head, and it's a paper wasp, meaning it makes
papery nests by mixing plant materials with saliva to create a sort of paper maché.
Schmidt gave its sting a 3, which he described as "Immediate, irrationally intense, and
unrelenting."
There isn't enough research on this species to know exactly what its venom contains, but
all other members of its genus that have been studied are armed with pain-inducing molecules
called kinins.
So the red-headed paper wasp probably has them too.
Kinins are a type of peptide, and like a lot of the other compounds in the venoms on this
list, they're among the many molecules involved in inflammation.
They cause pain by turning on pain-sensing nerves, and because they act on neurons directly,
they're called neurotoxins.
In solitary wasps, kinins are used to paralyze prey.
But social wasps usually don't capture their meals with their stingers—they use their
powerful jaws instead.
They reserve stinging for defensive battles, especially against mammals like us.
Per drop, most of their venoms are pretty weak.
People only die when they're swarmed by dozens of them, or if they're allergic.
But these wasps don't need deadly venoms.
A jolt of pain is enough to get a predator to back off, which can actually be more effective
in some ways.
Death doesn't let you learn.
And what their venom lacks in brute lethality they make up for in pain production.
The more painful the venom, the more effective the lesson to the would-be attacker—stay
away, or you'll regret it.
It's a strategy perfected by the next insect on our list.
Warrior wasps, sometimes called drumming wasps, are also native to the Americas, and also
live in big colonies.
As their name implies, they have an aggressive reputation, and an especially eerie way of
warning you of what's to come if you get too close to their nest.
When warrior wasps feel threatened, hundreds of them will rhythmically scrape their nest
in unison, creating a loud, drumming sound.
At the same time, they'll flap their wings to the beat, adding a seriously creepy visual
display to the noise.
Part of the reason for this ostentatious warning is that, like honey bees, their stingers are
barbed—so they stand to lose a chunk of their abdomen if they sting.
So it's much better for them if you listen to the drumming and keep your distance.
And it's really not a concert you want to be at.
Warrior wasp stings are excruciating.
Schmidt gives them wasps his highest pain rating, a 4.
In his words, the stings are "Torture.
You are chained in the flow of an active volcano."
The pain he experienced was so awful that for the first time, he even questioned his
decision to start his list.
But what's even more striking than the level-4 agony is how long the pain lasts.
Warrior wasp stings burn for over two hours.
So whatever causes such unrelenting pain, it must be pretty stable and hard for our
bodies to break down.
Schmidt thinks it's probably a kinin, just like the slightly less painful paper wasps,
but we don't know much about exactly what's in it.
Apparently researchers aren't too enthusiastic about analyzing some of the most painful venom
in the world.
Can't imagine why.
When you hear "tarantula hawk," you might picture a giant spider.
Or maybe a bird that eats spiders.
But tarantula hawks are neither of those things.
They're wasps in the genus Pepsis, found in the Americas.
They get their name because they're gigantic — they can be 5 centimeters long, big enough
that they can seem more like a bird than an insect.
And they feed their babies tarantulas.
They have a whole bunch of adaptations that help them go after such dangerous meals.
Their legs are long and gangly, allowing them to grapple even large, wriggling tarantulas.
And, of course, they produce a lot of venom that they use to subdue their prey.
Their stings cause Schmidt level 4 agony.
"Blinding, fierce, shockingly electric.
A running hair drier has been dropped into your bubble bath."
That's mostly because of the unusually high amount of acetylcholine in their venom.
Acetylcholine is something you use a lot in your nervous system, mainly to send signals
between neurons and to other cells.
It's basically the go-to neurotransmitter, and it triggers both your motor and pain neurons.
So not only does the sting hurt: it also makes any muscles nearby clench hard, which is both
painful and paralyzing.
That's the point — tarantula hawks use their venom to paralyze their prey, because
tarantulas generally don't like being eaten and would otherwise fight back.
Thankfully, at least for us humans, the effects of these stings don't last long—mere minutes.
That's because your body is already well-equipped to clean up acetylcholine.
Whenever a neuron releases the stuff, you have to remove any excess floating around
after the signal is received as quickly as possible.
If you didn't, you'd just keep triggering neurons over and over again.
So you have the enzyme acetylcholinesterase, which chops it up.
That means we can rid ourselves of tarantula hawk venom pretty quickly.
The spiders can too, eventually.
But by the time they regain control, they've already lost the battle, and become a meal
for the wasps' young.
Last and definitely not least, we have the bullet ant.
You might think the name for these Central and South American ants comes from the fact
that they're 2 or 3 centimeters long, so maybe about the size of a bullet.
You'd be wrong, though.
They're called bullet ants because being stung by one is supposedly just as painful
as being shot.
Obviously, Schmidt ranks them a 4—in some versions of his index, a 4+.
He describes their stings as "Pure, intense, brilliant pain.
Like fire-walking over flaming charcoal with a 3-inch rusty nail grinding into your heel."
Along with the pain, the stings often come with fever, sweating, trembling, and local
paralysis.
And that agony lasts forever.
Or at least it feels like forever.
Venezuelans call them hormiga veinticuatro, or "24 ant," in honor of the 24 hours
the pain sticks around for.
That's because the main pain-inducer in the venom, called poneratoxin, is an impressively
powerful neurotoxin.
Poneratoxin directly stimulates neurons by opening the sodium channels they use to send
electrical signals.
And it doesn't just do this once.
It does it over, and over, and over, and over, and over.
So there you have it: eight agonizing stingers, and what we've learned from the scientists
who willingly line up to study them.
There's still a lot we don't know about venom, but we can learn a lot about how our
bodies work at the molecular level by understanding how the compounds in them produce pain.
By studying them, researchers hope gain a better understanding of chronic pain, and
maybe even find new ways to treat it.
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