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  • In nearly every corner of the earth, ants wage war against each other.

  • Their weapons are what nature gave them. Some have strong armor, deathly stingers, or sharp mandibles.

  • And then there's this tiny and not very impressive ant,

  • but it rules the biggest empire any ant has ever built.

  • A colony spanning continents and fighting wars that leave millions of casualties.

  • Let's take a look at this unlikely warrioress,

  • "Linepithema humile" the Argentine ant.

  • Kurzgesagt intro music

  • This story begins in the floodplains around the Paraná River, in South America,

  • It's a crowded ant megalopolis where dozens of ant species fight for dominance,

  • including fire ants, army ants and the rather unimpressive Argentine ant.

  • It measures only 2 to 3 millimeters in length and with its small mandibles,

  • it's surprising that it survived among its buff competitors.

  • Their homes are equally unremarkable.

  • Their colonies range from fairly small to very large and could be found anywhere:

  • Under logs, in loose leaf litter or the former colonies of other ants.

  • Here, Argentine ants prepare their most effective weapon against their competitors: bodies.

  • Most ant species have only one queen to produce ants,

  • while Argentine ants went all-in on numbers.

  • For every 120 workers there's one queen,

  • laying up to 60 eggs a day.

  • So their colonies grow fast and have millions or billions of individuals.

  • Teams of queens and workers frequently branch out and found new colonies.

  • But this strategy has a downside: As colonies grow and produce a lot of offspring,

  • mutations occur and new colonies adapt to new environments.

  • Their DNA slowly changes from generation to generation and differences accumulate.

  • So after a while the ants that left the colony

  • will become more like distant cousins and start to compete with their mother colony.

  • In their native South American range, this is how Argentine ants behave.

  • Within their colonies they are very cooperative and well-organized,

  • but they fight vicious wars against other Argentine ant colonies and other ant species

  • With equally strong opponents on every side,

  • the Argentine ant became extremely aggressive, fighting for every inch of ground.

  • But it could never dominate its neighbours... until humans showed up.

  • We did what humans do and transported things around the world by ship.

  • On one of them, a few Argentine ant queens hitched a ride as stowaways

  • from South America to Madeira and New Orleans.

  • The Argentine ants suddenly found themselves in a strange world.

  • Instead of being surrounded by deadly enemies,

  • they found only victims ⁠— nobody could fight them effectively.

  • Because only a few Argentine ant queens were introduced to the outside world,

  • the resulting colonies had very low genetic diversity.

  • On top of that, the introduced Argentine ants

  • kill up to 90% of their queens every year.

  • Fewer queens, less genetic variation.

  • So, as these colonies spread across the landscape,

  • ants that left the colony were no longer considered distant cousins.

  • As a result, the new colonies form not opposing but cooperating parties called "supercolonies".

  • This is a very uncommon strategy in the ant kingdom,

  • only a few of the 16,000 ant species have evolved supercolonies.

  • A supercolony was established on the West coast of the USA

  • and became a base for the tiny ants' global conquest.

  • Today, the Argentine ant inhabits the Mediterranean zones of six continents and many islands.

  • This one supercolony was especially successful,

  • establishing sister locations in California, Europe, Japan, New Zealand and Australia,

  • forming one massive intercontinental megacolony of Argentine ants.

  • This makes them the largest society on Earth, more numerous than even the human one.

  • But their success has changed the ecosystems they invaded.

  • California is a perfect example of this.

  • In their greed for more territory,

  • the invading Argentine ants have overrun and replaced 90% of the native ant species,

  • including several species of Californian carpenter ants.

  • Although carpenter ant workers are giants,

  • their colonies have only between 3,000 and 6,000 individuals

  • and stand no chance against an expanding supercolony of billions of Argentine ants.

  • Argentine ant workers attack by wiping toxic chemicals on their victims

  • which irritates the enemy and marks them as a target for other Argentine ants.

  • When they attack, the Argentine ants wash over their victims,

  • clinging on to their opponents in groups and pulling apart their limbs.

  • It doesn't matter how many of them die ⁠— there are always more.

  • Once the colony is overrun and exterminated,

  • the Argentine ants feed on their victims brood and take over their home and territory.

  • The Argentine ants' numbers allow them to hunt down and devour such an excessive mass of different insects

  • that over time some species disappear from the ants' territory completely.

  • Argentine ants don't care about working with the local flora and fauna,

  • they consume them and move on.

  • And, if their next stop happens to be human property,

  • they will rudely make themselves at home there too.

  • They forage in dumpsters, bowls of pet food and sneak into kitchens to claim leftovers.

  • Not just our homes: our gardens and fields are also impacted by Argentine ants,

  • since they tend to hordes of aphids as their cattle.

  • The aphids feed from plants and produce a sweet honeydew, which they trade with the ants for protection.

  • Since the ants have no major enemy to fear in their new homes,

  • the aphids thrive and ultimately kill the plants they live on.

  • So, on top of being a major disruption for the ecosystems they invade,

  • they are also a huge pest for agriculture.

  • But the rule of the Argentine ant is being challenged.

  • Parts of the super colonies have broken off and become their own empires.

  • A merciless civil war has broken out.

  • For example, the Lake Hodges Supercolony has been fighting against the Very Large Colony

  • for years in San Diego County.

  • A massive war is going on over a dynamic front line stretching over kilometers,

  • an estimated 30 million ants die here each year.

  • On other fronts, an old acquaintance from the Parana River has risen from the shadows

  • Red imported fire ants,

  • which were accidentally introduced from their old home to the coast of Alabama,

  • Not only are the red fire ants fierce fighters and more than able to deal with the

  • Argentine ant, they are also able to form super colonies themselves.

  • Now the old wars from their distant home have been taken to a foreign battleground.

  • In the southeastern US the super colonies clashed fiercely.

  • The Argentine ants found themselves outgunned by the fire ants. The fire ants major workers are

  • more than twice the size of the Argentine ants and wield venom-injecting stingers,

  • even though the Argentine ants fought fiercely, the fire ants were too much for them.

  • After countless lost battles the red imported fire ant

  • exterminated the Argentine ants super colony from much of the southeastern US.

  • This is one territory lost but the Argentine ants will fight on.

  • This amazing network of cooperating super colonies is the biggest success in their history.

  • And they'll not give it up because of a small defeat.

  • They will stand their ground against any enemy that might arise.

  • No matter if it's on the Paraná River

  • or on one of the large battlefields across the world.

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  • *Kurtzgesagt duck quacks while floating through space* ♫ Outro music

In nearly every corner of the earth, ants wage war against each other.

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