Leafcutter Ant

Mary Fitzpatrick

Kingdom: Animalia

Phylum: Arthropoda

Class: Insecta

Order: Hymenoptera

Family: Formicidae

Genus: Atta

Species: A. cephalotes

Morphology

A. cephalotes are reddish brown in color, with very long, skinny legs. Only males and queens are alate, and have wings. Their distinguishable characteristics can be defined by their 11 segmented antennae with a club end, three pairs of spines with a smooth exoskeleton, and strong polymorphism (Hölldobler, and Wilson, 2010). Sizes of A. cephalotes ranges from 1.5mm to 3cm, depending on the caste that the ant is in inside the colony. Female workers are variable in size, depending on what type of job they have in their colony. They are a darker brown, and have mandibles with sharp jagged "teeth" used for leaf cutting (Cherrett, 1968) . Soldiers have the same morphological characteristics as workers, except are slightly larger, averaging around 18 mm. Many queens can grow up to 20 mm with wings that grow beyond their thorax.

Habitat and Distribution

The genus Atta are neotropical leafcutter ants that are native to South America, Central America, and Mexico (Correa et al., 2005) . A. cephalotes prefer to create their colonies in secondary forests or disturbed forests compared to old growth primary forests due to their adaptation in gathering leaves with high nutrient content in shade tolerant plant species (Farji‐Brener, 2001). Other than rainforests, A. cephalotes have adapted to living in any habitat with enough plant material, including agricultural plantations. Millions of members in a colony can span up to 100 square meters. Several underground nests are excavated by the colony, with each nest containing a fungus garden for nursing larvae. Each nest cavity is connected to each other by a tunnel system.

Social Caste

Queen- Queens are the largest ant of the colony, and only one queen is present in every colony, unless in the rare case where the colony size is too large. The sole task that queens have are to reproduce and to initiate new colonies, and can live for more than 20 years leading the colony (Peregrine, 1975). During October to December during the mating season, virgin queens will take a nuptial flight, and mate with several different males, gathering enough sperm to last her up to 20 years. After mating, the virgin queen will lose her wings and start excavating tunnels for her new colony. The queen will produce fungal spores from her mouth and collect leaf litter for nutrients for her soon to be hatched eggs. The queen will produce around 150-200 million eggs in her lifetime. After the colony expands, the queen will stay in the main chamber and take care of new brood the rest of her lifetime.

Male- Males hatch from eggs that were not fertilized during the mating process. Males serve no purpose in maintaining the colony, with the only task being mating with other queens (Marquez, 2020). Male eggs will not be laid unless the colony is ready to expand into new colonies. Soon after mating with females during their nuptial flight, they will die soon after.

Worker- Workers are infertile females, and range in size significantly. Depending on the size of the worker, they will have different tasks for the colony. Workers will live up to 6-10 weeks.

Maxima workers are the largest ants or the worker caste, and do the majority of foraging, leaf cutting, and transportation back to the colony (Marquez, 2020). Media workers are the second largest workers, and assist maxima workers by cutting leaves into smaller pieces, and aiding in the transportation of leaves back to the colony. Minors are the second the smallest ants, and work inside the colony by cutting up the leaf litter into pieces and planting them into the garden substrate inside the nest cavities. Minors will treat the leaves with fecal liquid, put the leaf pieces into the substrate, then pluck a few fungal threads called mycelium from an older garden and plant them with the new leaf substrate. The smallest workers are called minims, and their primary role is to take care of the brood and watch over the fungus gardens. Minims can also hitchhike on top of the leaves that the larger works bring back to the colony (Linksvayer et al., 2002). Many parasitic flies attempt to lay their eggs onto the heads of the foragers, so minims are used as a defense against any attacks against foreign contaminants.

Soldier- Soldiers are also infertile females, but are slightly larger and do not leave the colony to forage for leaf litter. Instead, they are used for defense against dangers to the colony. When a danger is sensed trying to get inside of the colony, the soldiers will leave the colony and attack the threat with their sharp and powerful mandibles (Marquez, 2020).

Diet

When cut leaves are brought back to be created into a fungus garden, the fungus will break down the leaf's cellulose, which cannot be broken down by the ants themselves. As the fungi grows from digesting the leaf litter, the ants collect the fungi's nutritional body that contains xylan and starch, and use it to feed the brood and adults (Cherrett, 1968) . The ants and fungi form a true symbiosis, where both partners benefit from their relationship. The ants gain nutrients to feed the colony, while the fungi is provided a well established environment for growth. Besides fungus, worker ant also feed on plant sap as nutrients to give them energy during their forage (Cherrett and Quinlan, 1979) .

Works Cited

Cherrett, J. M. (1968). The Foraging Behaviour of Atta cephalotes (Hymenoptera and Formicidae). I. Foraging pattern and plant species in tropical rain forest. Journal of Animal Ecology. 37: 387-403.

Cherrett, J. M. and Quinlan R. J. (1979). The role of fungus in the diet of the leaf-cutting ant Atta cephalotes (L.). Ecological Entomology. 4: 151-160.

Correa, M.M., Bieber, G.D. and Leal, I.R. (2005). Occurrence of Atta cephalotes (L.) (Hymenoptera: Formicidae) in Algoas northeastern Brazil. Neotropical Entomology. 34: 695-698.

Farji‐Brener, A. G. (2001). Why are leaf‐cutting ants more common in early secondary forests than in old‐growth tropical forests? An evaluation of the palatable forage hypothesis. Oikos, 92(1), 169-177.

Hölldobler, B., & Wilson, E. O. (2010). The leafcutter ants: civilization by instinct. WW Norton & Company.

Linksvayer, T. A., McCall, A. C., Jensen, R. M., Marshall, C. M., Miner, J. W., & McKone, M. J. (2002). The Function of Hitchhiking Behavior in the Leaf‐cutting Ant Atta cephalotes 1. Biotropica, 34(1), 93-100.

Marques, Diana. “Ants and Their Garden.” Diana Marques, American Scientist, 16 Mar. 2020, https://www.dianamarques.com/portfolio/ants-and-their-garden/.

Peregrine, D. J. "Some Field Observations on the Bachacs of Trinidad. First printed in Journal of the Trinidad & Tobago Field Naturalists' Club, 1975.

Page updated

Google Sites

Report abuse