Puke, poop and tiny cockroaches: How the leafcutter ant queen runs her farm - Charles Wallace
In this south Texas clearing,
an ancient tale that ties the members
of four species together is unfurling.
The first involved is our soon-to-be
queen leafcutter ant.
The second is this fungus, a piece of
which she scoops into her mouth pocket.
The third are these tiny cockroaches,
which nestle under her wings.
And the fourth is the one
that threatens them all.
But it’ll reveal itself later.
In a flapping-wing frenzy,
our ant takes to the sky.
This is the only chance
she’ll have to mate,
so she stores as much sperm as she can
from the males she meets in midair.
After dropping to the ground,
she sheds her wings and begins digging.
She excavates a tunnel and a side chamber,
then plugs the entrance,
sealing herself in.
There, she regurgitates the fungus.
This pile of puke will form
the bedrock of her kingdom.
Over the following weeks,
in between laying eggs
and consuming the infertile ones,
she tends to her developing fungal garden,
fertilizing it with feces.
Finally, her first offspring surge
forth and establish a rhythm.
Soldiers guard the nest while foragers
set off to find tender foliage.
The larger foragers,
equipped with powerful mandibles,
anchor themselves on leaves
and chomp away in a wide arcs.
Holding these pieces aloft,
which can weigh more than eight times
their body mass,
the workers march back to the nest.
Meanwhile, the colony’s smallest ants
clean the leaf fragments
of debris and pathogens.
But the colony doesn’t eat these morsels.
Instead, the ants use them
to sustain their fungus,
which, in turn, sustains the colony.
More than 10 million years ago,
leafcutter ants domesticated fungus.
Like many of our crops,
the fungus they farm
is genetically distinct
from its wild relatives
and can no longer survive
without their help.
Reciprocally, the fungus provides
the ants with an essential amino acid
and digestive enzymes they’ve lost.
Once the workers return
to the nest with their spoils,
they crush up the leaves,
making their offerings easier
for the fungus to consume.
Foragers work tirelessly
over the following months.
They create thousands of trails,
stretching hundreds of meters.
All of them are perfumed
with the ants’ pheromones
and constantly cleaned
to function as efficient highways.
Meanwhile, the queen lays thousands
of eggs every day
and is tended to by members
of her entourage,
which nourish her
with the large, infertile eggs they lay.
Among enclosures containing
garbage and growing larvae,
workers tend fungal gardens in various
chambers throughout the colony.
They prune bits of the fungus
to stimulate growth
and strategically open and close
surface tunnels,
controlling the humidity.
But ants aren't the only
animals down here.
Tiny cockroaches like those that
originally crept under the queen’s wings
feed opportunistically off the fungus.
Each could fit on the head of a Q-Tip.
They hitch rides on soon-to-be queens,
and make their way
to more established colonies.
Inside the leafcutter nest,
they’re undercover:
closely mimicking the ants’
signature scent,
they frolic and feed
in the fungal gardens,
mostly undetected.
And here’s where this tale’s antagonist
rears its virulent fruiting body:
our elusive fourth character is a
parasitic micro-fungus called Escovopsis.
If left unchecked, it would destroy
the fungal gardens and the ants
and the cockroaches that depend on them.
The leafcutters mount
a barrage of defenses.
They rigorously weed Escovopsis out
and partner up with different
microorganisms like yeasts and bacteria
to stunt its growth.
Eventually, the leafcutter colony covers
several meters of underground tunnels,
comprises millions of workers, and can
defoliate a tree in a single night.
The queen’s kingdom will persist
as long as she does,
which may be over a decade.
Every spring, some of the queen’s
offspring prepare to leave.
They grab a piece of home
and crowd the surface chambers,
preparing to fly off and mate,
beginning the cycle anew.
