Hi, my name's Jordan Dean.
In this video we're going to be looking into the lives of the exceedingly infamous Argentine
Ants.
Argentine Ants, known scientifically as Linepithema humile, are native
to parts of South America.
But through human activity, they’ve now established themselves all over the world
and are considered to be one of the worst invasive ant species out there.
The ants are highly problematic to introduced regions, as they can disrupt the fragile balance
of the native ecosystems, and subsequently, diminish their levels of biodiversity.
They do so by displacing native animal populations.
Taking them as prey, and or, out competing them for resources.
Many native ant species often fall victim to these invaders.
As the Argentine Ants prey upon insects commonly eaten by these natives, and are often much
faster in discovering them too, leaving little to no food around for them to consume and
develop their colonies.
They’re also extremely hostile towards any rival ants.
Here you can see some Argentine Ants aggressively fighting over this source of food, which was
initially discovered by this native species of Big-headed Ants…The native ants defend
their find with everything they’ve got…But in the end, their efforts are wasted, as the
Argentine ants overwhelm them with their superior numbers…So a source of food which was once
feeding a native colony, is now promoting the strength of these troublesome invaders…
Argentine Ants are also known to invade the nests of smaller ant colonies.
Here, they’re raiding the nest of another native species.
so as to feed their ever growing colony.
But why should it matter if one ant species is replaced by another?
Well, the weakening and eventual loss of these native ant colonies, greatly impacts the ecology
of the area.
The natives are perfectly adapted to living alongside and subsequently supporting the
local plants, by cycling and enriching their soil...
dispersing and protecting their seeds...
and sometimes, even aiding in their pollination too.
Once Argentine Ants replace these native ants, all of a sudden, the seeds, once tended to
by the former ants, are left untouched, as the Argentine Ants have little to no interest
in the seeds or favor the seeds of different plants, like nonnatives and weeds.
They also don’t dig very deep within the ground like most ants do.
Instead, they prefer to nest fairly close to the grounds surface.
This too negatively effects the surrounding plant life, as they lose the assistance of
having well cycled and enriched soil, which the native ants readily provided.
Argentine ants can even attack such animals directly, overwhelming them with their immense
Targeting birds and reptiles by invading their nests and consuming the vulnerable young as
they hatch.
So what makes these Argentine Ants so successful at dominating their surrounding environment?
They aren’t overly large, only measuring 3-4mm in length, and don’t possess venomous
stings like Fire Ants do, or have the ability to spray acid like Yellow Crazy Ants.
But instead, these ants possess some highly advantageous abilities, and what they lack
for in size and lethality, they greatly make up for in numbers.
Normally, when you have two separate ant colonies come together, even those of the same species,
they clash, sometimes, having to fight out to the death in order to protect or expand
their territory.
The reasoning for this is because the foreign ants have a different chemical profile to
those of their own colony.
Native colonies of Argentine Ants are no different.
They form relatively small colonies which are genetically diverse, each having its own
unique scent.
But the introduced Argentine Ants are unlike those from their homeland.
Because there has been little to no diversification, they are genetically similar, and so, possess
chemical profiles which are almost identical from colony to colony.
So ants from separate colonies, tens, hundreds, even thousands of kilometers apart, rarely
compete with one other.
Instead, they cooperate.
To demonstrate just how cooperative these Argentine Ants can be, we’re going to be
looking inside the nest of captive colony.
Currently, the colony is only quite small, with under 100 total individuals.
But in a few moments, this colony is about to triple in size.
Inside this vile, I’ve got a bunch of ants and brood which I’ve collected from a mature,
foreign colony of Argentine Ants.
So let’s see what happens when I expose them to this young colony here…
As soon as the lid’s taken off, they’re away, scanning the surrounding area and surveying
their options...
Within a short while, they discover the foreign nest, and shortly after, start picking up
all their brood and moving them straight in with theirs…
In virtually all other species of ants, this combination of two different colonies would
result in complete chaos, and each group would be fighting it out to the death.
This cooperative merging together of colonies, means these Argentine Ants are able to form
colonies on a massive scale, spanning hundreds, even thousands of kilometers.
The ants are also polygynous too, meaning they will accept more than one egg laying
queen within their individual colonies.
Notice these slightly larger ants here?
These are actually all queen ants, and each colony often has at least several of these
queens present.
Resulting in large batches of eggs being laid and rapid growth of the ants’ population.
They’re also incredibly adaptable when it comes to their nesting environment.
Typically, they nest beneath rocks and leaf litter...
and in and underneath logs...
and sometimes, even up within the trees.
And they’re highly mobile too.
Often up and moving their entire colonies if the conditions aren’t favorable.
After this captive colony’s recent spike in population, they’re starting to look
a little cramped within their little test tube, and naturally, would be scouting around
for a preferable nesting site.
So what I’ve done here is attached up an alternative space for them to explore, a small
prototype formicarium we’ve been working on here at Ants Australia.
The new area is kept both humid and dark.
Ideal living conditions for the colony.
Almost as soon as it’s attached up, the ants begin inspecting the new space…
Once they deem it suitable, the message is spread rapidly throughout the colony.
And within moments, the ants start moving on in, brood, queens and all...
Before long, their old nest is completely abandoned in favour of the new…
Argentine Ants also use their speedy repositioning skills for another important purpose, reproduction.
Typically, when ants undergo their nuptial flights, the winged reproductive ants, known
as alates, fly off in search of foreign alates to mate with.
The newly mated queens will then shed their wings, and search for a safe place to lay
their eggs and form new colonies.
Argentine Ants are a little strange, in that the female alates have wings, but rarely ever
use them.
Instead, most of the mating actually occurs within the ants’ nests.
They’re able to spread in a process known as “budding”.
This is where ants branch off on foot, in groups consisting of a single queen or more,
along with a number of worker ants.
Each group then relocates and establishes themselves within new nesting sites.
So the ants are effectively dividing and multiplying their numbers, gradually expanding the territory
of their species.
A far less perilous method when compared to the more common, nuptial flights.
From appearance alone, Argentine Ants look rather ordinary and insignificant.
But withall their exceptional traits, like being able to merge their colonies...
Their tolerance of multiple queens...
Their ability to occupy a large variety of habitats...
And their exceptional colony manoeuvrability...
you can see just why they are such a dominant species and are so
effective at monopolizing their surrounding environments.