||This article possibly contains original research. (December 2010)|
|Atta cephalotes worker carrying leaf segment|
Atta cephalotes is one of 41 species of leafcutter ant. This species is part of the Attini tribe (the fungus-growing ants). A single colony of ants can contain up to 5 million members, and each colony has one queen that can live more than 15 years. The colony comprises different castes, known as ‘task partitioning’, and each caste has a different job to do.
Biology and behaviour
Ants are split into different castes. Soldiers are the largest of the ants and they often stand guard at the entrance of the nest, or will even go on scouting missions to watch for predators. Workers, who are all female, are divided into two types, media and minima, that both have big jaws and sharp teeth. Media workers are the larger of the two, and they cut the leaves and bring them back to the nest. These ants are able to navigate to the source of leaves by following the pheromone scent of the other ants ahead, a process known as ‘tandem running’. Once the media workers have deposited the material into the nest, slightly smaller workers called ‘minima workers’ cut up the leaves into small pieces and then feed it to a fungus they cultivate. They also cover the leaf in antibacterial saliva which stops other types of fungus growing.
A special caste of workers manage the colony's rubbish dump. These ants are excluded from the rest of the colony. If any wander outside the dump, the other ants will kill or force them back. Rubbish workers are often contaminated with disease and toxins, and live only half as long as their peers.
The smaller ‘minima’ workers feed the entire colony of ants. These minima workers also act as guards and follow the media workers or hitch a ride on the leaf they’re carrying to the source of the leaves and attack small parasitoids called phroid flies.
The queen is larger than the other females and is winged. Her role is to give birth to workers.
The females can be workers or soldiers, and cannot produce workers but instead produce males only.
Males are also winged, and their only role is to inseminate the virgin queen.
The leaves that the worker ants cut are not for their consumption, as it is toxic to ants. Instead, the minima ants feeding it to a fungus that they farm.
Across the rainforest floor they occupy an area typically an area of approximately 20 feet. They live in nests that can be as deep as 7 metres that they have carefully positioned so that a breeze can rid the nest of the dangerous levels of CO2 given off by the fungus they farm and eat.
Evolution and history
Leaf-cutter ants are an extremely specialised species. It has evolved over 25 million years to have a symbiotic relationship with the fungus it farms.
Mating in Atta cephalotes requires flight, which is why the queen and the males are winged. In preparation, the queen will store some fungus in a pouch in her mouth to begin cultivating in her future colony. The process starts with the queen flying up off the ground. The male will then join her and inseminate her, at which point he is no longer needed and dies. The queen will reach the ground and very quickly lose her wings, and will then look for a suitable place to begin a new colony. Once an adequate place is found, she will start digging into the earth and release a bit of the fungus she had previously stored to begin the process of a new underground system.
|Wikimedia Commons has media related to Atta cephalotes.|
- "Species: Atta cephalotes". AntWeb. 2010-06-30. Retrieved 2010-08-20.
www.arkive.org/leaf-cutter-ant San Francisco State University Department of Geography www.thewildones.org