Aregentine Ants Rule the World!

[Big Orange]

BBC

Ant mega-colony takes over world
Page last updated at 10:41 GMT, Wednesday, 1 July 2009 11:41 UK
Matt Walker
Editor, Earth News

A single mega-colony of ants has colonised much of the world, scientists have discovered.

Argentine ants living in vast numbers across Europe, the US and Japan belong to the same inter-related colony, and will refuse to fight one another.

The colony may be the largest of its type ever known for any insect species, and could rival humans in the scale of its world domination.

What's more, people are unwittingly helping the mega-colony stick together.

Argentine ants (Linepithema humile) were once native to South America. But people have unintentionally introduced the ants to all continents except Antarctica.

These introduced Argentine ants are renowned for forming large colonies, and for becoming a significant pest, attacking native animals and crops.

In Europe, one vast colony of Argentine ants is thought to stretch for 6,000km (3,700 miles) along the Mediterranean coast, while another in the US, known as the "Californian large", extends over 900km (560 miles) along the coast of California. A third huge colony exists on the west coast of Japan.

While ants are usually highly territorial, those living within each super-colony are tolerant of one another, even if they live tens or hundreds of kilometres apart. Each super-colony, however, was thought to be quite distinct.

But it now appears that billions of Argentine ants around the world all actually belong to one single global mega-colony.

Researchers in Japan and Spain led by Eiriki Sunamura of the University of Tokyo found that Argentine ants living in Europe, Japan and California shared a strikingly similar chemical profile of hydrocarbons on their cuticles.

But further experiments revealed the true extent of the insects' global ambition.

The team selected wild ants from the main European super-colony, from another smaller one called the Catalonian super-colony which lives on the Iberian coast, the Californian super-colony and from the super-colony in west Japan, as well as another in Kobe, Japan.

They then matched up the ants in a series of one-on-one tests to see how aggressive individuals from different colonies would be to one another.

Ants from the smaller super-colonies were always aggressive to one another. So ants from the west coast of Japan fought their rivals from Kobe, while ants from the European super-colony didn't get on with those from the Iberian colony.

One big family

But whenever ants from the main European and Californian super-colonies and those from the largest colony in Japan came into contact, they acted as if they were old friends.

These ants rubbed antennae with one another and never became aggressive or tried to avoid one another.

In short, they acted as if they all belonged to the same colony, despite living on different continents separated by vast oceans.

The most plausible explanation is that ants from these three super-colonies are indeed family, and are all genetically related, say the researchers. When they come into contact, they recognise each other by the chemical composition of their cuticles.

"The enormous extent of this population is paralleled only by human society," the researchers write in the journal Insect Sociaux, in which they report their findings.

However, the irony is that it is us who likely created the ant mega-colony by initially transporting the insects around the world, and by continually introducing ants from the three continents to each other, ensuring the mega-colony continues to mingle.

"Humans created this great non-aggressive ant population," the researchers write.

While very interesting, it is a great way to reduce the worldwide genetic diversity amongst ants.

[Serafina]

So, basically, all the ants of this "super colony" are descendants from a single ant colony, which prevents them from attacking each other?

Thats nothing new - i guess the only real difference is the speed of the spread of the new colonies. After a certain amount of time has passed, they should attack each other.

And really, calling it a "super colony" just because they do not attack each other is a bit overdone.

[FireNexus]

While very interesting, it is a great way to reduce the worldwide genetic diversity amongst ants.

This is unfortunate, but there really is no way to truly prevent the spread of this type of ant. This is a species where reproductive queens go out and forage with the workers because they have so many in single colonies. It is an unfortunate fact of our existence that we will inadvertently spread some species. Short of irradiating every single cargo container that moves across the planet, or covering all of our cars, ships and airplanes with boric acid, what would you have us do to stop it?

[Simon_Jester]

So the the Argentine Ant Collective conquers the world... and if we weren't diligent about entomology, we'd never notice. Heh.

Of course, conversely, the ants probably wouldn't notice if some random country (say, Fiji) conquered the world.

Could it reasonably said that we live in different worlds? If I can conquer "the" world without you noticing, that would tend to indicate that you don't really live in the same world I do, even if you happen to live in my backyard.

[Sea Skimmer]

This is unfortunate, but there really is no way to truly prevent the spread of this type of ant. This is a species where reproductive queens go out and forage with the workers because they have so many in single colonies. It is an unfortunate fact of our existence that we will inadvertently spread some species. Short of irradiating every single cargo container that moves across the planet, or covering all of our cars, ships and airplanes with boric acid, what would you have us do to stop it?

Ideas like that are being worked on actually. The most urgent part of the problem is ship ballast water since you can’t even try to visually inspect it and you can’t avoid pumping local life forms onboard. Then you sail to some other port, unload the ballast and you’ve just gone and dumped as much as 50,000 tons of foreign water into a coastal ecosystem.

A microwave system which will kill everything in the water when its pumped back overboard is now being worked on by Raytheon, and once its perfected you can expect the US, Europe and Japan will quickly introduce laws to make it mandatory equipment. But as you can imagine, irradiating that much water in a timely fashion (it takes about 12-24 hours for a big ship to dump all its ballast) demands one hell of a microwave rig.

[FireNexus]

That actually makes a lot of sense, and I hope like hell the law requires that equipment when it becomes available. What about insects in grain or other food shipments, though? I can't even manage to effectively remove ants from my counter, and it's a small area I can (theoretically) easily control. In a cargo ship?, or even a shipping container filled with stuff? Good luck. Are there methods available to halt this, as well?

[Big Orange]

Could these Argentine ants face a die back similar to the bee's colony collapse, due to their lack of genetic diversity world wide, after their widely dispersed colonies exapand to unsustainable levels?

[FireNexus]

If they do, that's probably bad for everyone. They've displaced a lot of native ant species, and ants are pretty ecologically important everywhere. With luck, there are enough native ants to refill the gap, but they may not be the case everywhere.

[Erik von Nein]

Could these Argentine ants face a die back similar to the bee's colony collapse, due to their lack of genetic diversity world wide, after their widely dispersed colonies exapand to unsustainable levels?

They aren't clones of each other, you know, nor are the necessarily genetically near-identical. The reason colony collapse has been so bad is because of breeding practices, feeding practices, and the choice of bee species.

It's similar to comparing banana farms to a field of wild grass. While the bananas are all essentially identical (yes, the bee colonies aren't clones of each like banana trees, but bear with me), the grasses aren't, even if they were all from two progenitors, precisely because of sexual reproduction and without the influence of humans choosing breeding pairs.

If they've expanded to unsustainable levels then you're more likely to see local die offs rather than a sudden collapse of the entire family.