Here you are, on a vacation to Guatemala. You're
lying on a hammock near the Central American rainforest, when you find there
are ants all over you, coming from a nearby tree. You fall off your hammock,
and that's when you notice the ants are carrying leaves... you
think aloud. "They are probably going to eat that stuff!"
You may have a similar experience at several locations
in Central and South America, but many species live as far north as Oklahoma.
However, this ant, known as the Leafcutting Ant, does not eat leaves. The
leaves it carries to its nest are fed to a special type of fungus that these
ants grow. The species of this harvest fungus depends on the species
of the ant. The fungus "garden" is located deep underground within the ant
colony. The average ant nest contains several of these gardens, each with
an average life span of about 3-5 weeks. As leaves reach the nest, they are
cut up into a gooey mulch and licked clean of all other fungus spores that may
interfere with the growth of the harvest fungus. Licking the leaves also
helps get rid of natural antibiotics. Next, in a clean terrace within the
nest, the plant matter is laid out and covered with fecal droppings. The
fecal matter acts as fertilizer and breaks down the proteins that the fungus
can not. Finally, a piece of fungal hyphae (the growing, nutrient-using
part of the fungus) is placed on top of the plant matter. As it grows, a
part called the gongylidia (gong-ee-lid-ee-ah) of the fungus is fed to
the members of the colony.
THE QUEEN AND HER SUBJECTS
A colony of Leafcutting Ants is comprised of several
castes. Most of these are female. Males, who hatch from unfertilized eggs
are drones, and die shortly after mating with the queen. Drones are
considered lazy and inferior members of the colony, since all they do is
eat and lie around until they are mature enough to mate. Only queens
and drones can mate. Most colonies have only one queen, but sometimes there
is two or three, especially in large colonies. Other castes include minors
('nursers'), medians ('workers'), and majors ('soldiers'). These are all
essentially workers, besides the fact that they have specialized jobs and
different sizes. Queens and drones are the only ants in the colony
that can fly. Ants with wings look much like stingless wasps. The queen
loses her wings after she mates .
The queen's job is to lay eggs and found new colonies.
When a newly forming queen wants to found a new colony, she takes a chunk
of fungal hyphae from a garden and tucks it into a special pocket in her
head. Then, she flies away in search of a drone. When she finds one, she
mates with it. After she mates, she looks for a suitable spot for a colony
and digs her nest. Soon, she starts laying her eggs. A queen may lay thousands
of eggs every day! The first hatched ants
immediately begin their work. The workers, which form the largest caste in
the colony, strip leaves off trees and take them back to the nest. Trees
immediately in the vicinity of a Leafcutting Ant nest are usually stripped
bare of leaves. Once the workers deposit their leaves, the tiny
nurser workers chew them up and lay them down. They also tend for the
larvae and eggs in the colony. The gargantuan soldiers defend the colony
and provide escort to the workers from enemy ants and predators.
IT'S A ROUGH LIFE FOR AN ANT
Ants, in general, have many enemies. Spiders often
come upon ants that have fallen into their webs, providing them with a
scrumptious snack. 'Hunter' spiders are spiders that do not trap their pray,
but actually chase it. They also prey on ants. Anteaters also eat ants, hence
their name. There is even an insect called the antlion that builds a trap
nest similar to an ant's. The nest lures ants to its opening, where the antlion
awaits it with gaping jaws. Ants even fight each other! Some computer
games depict black ants attacking red ants; this is not an accurate
scenario. Ants may very well compete with members of their own species,
regardless of color. In fact, it is more likely that these ants will attack
their own species since they get food from a common source. This is why soldiers
are essential parts of any colony.
HELLO, COUSIN
Let us now turn our attention to the relatives,
and non-relatives of Atta cephelotes. Termites look and act like ants. In
fact, many people think of them as "white ants". This is untrue. In fact,
termites belong to a completely different order. However, they are incredibly
similar in many ways. This phenomenon is called convergent evolution. The
true relatives of the ant are bees and wasps. They all have a hard exoskeleton
with three distinctive body regions. Paper wasps, ants, and bees all have
similar, yet complex social structures. Also, if you look at an ant drone
or queen, you'd notice that they look remarkably similar to wasps. In addition,
several ant species, such as fire ants, have stingers similar to the ones
bees, hornets, and wasps carry. Amazingly, ants, bees, and wasps are
related.
WHAT AN ANT!
The Leafcutting Ant is incredible. They have one
of the most complex social structures in the world, even amongst its relatives.
The leaves the Leafcutting Ant carries to its nest are 30 times their weight, a feat equivalent to a human carrying a bulldozer. They build mounds containing three hundred and fifty cubic meters of soil, right
above an underground city of three thousand chambers and four million ants,
the approximate population of Arizona. Needless to say, the Leafcutting Ant
is one cool insect.
Come see a Leafcutting Ant colony at the Orkin Insect Zoo in
the Smithsonian, National Museum of Natural History !
Leafcutting
Ants
