Atta on Display

LEAF-CUTTING ANTS ON DISPLAY Their amazingly sophisticated societies, perpetually active foraging columns, and incredible gardening behavior make leaf-cutting ants fascinating candidates for observation and study. Zoos and museums exhibit live colonies because of their effectiveness as display animals, applicability to educational programs, and relatively simple husbandry.
Both Acromyrmex and Atta species are used, though the comparatively spectacular coloniesof the latter are far more interesting and are preferred for exhibit. Several species of Atta are currently on display, but most institutions work with A. cephalotes, commonly encountered in the tropical forests of Central and South America and the Caribbean. The standard display technique for leaf-cutting ants is to house their fungus gardens in an observation nest connected to a foraging area.
	At the Cincinnati Zoo Insectarium, the leaf-cutting ant exhibit consists of a display colonyaccompanied by graphics and text illustrating the ants' social organization and gardening behavior. The observation nest is a naturalistic, underground cut-away showing ant tunnels and fungus garden chambers intertwined with plant roots. To maintain a large, active, and thus effective display population, additional fungus gardens are cultivated by the ants in plastic boxes off exhibit, but linked to the observation nest with clear plastic tubing.
The queen is kept trapped in public view in a special chamber within a centrally located garden.Small holes in this royal cell allow attendant workers ready access to the queen while preventing her escape. It's advantageous to know the queen's whereabouts when servicing the display, especially because excess workers and gardens are occasionally culled from the colony for population control and to stimulate fungal growth.
The foraging area is like a dense tropical forest, decorated with twisted vines and fallen logs and supplied daily with a generous portion of leafy branches. During special public events or programs, the ants may be offered an array of bright flowers, creating an entertaining rainbowof colorful parasols marching nestward. The ever active colonreadily captures the attention of the public and is one of the most popular displays at the Cincinnati Zoo!
	Some organizations have developed interesting display modifications. The London Zoo in England utilizes free-standing glass containers as garden chambers, highlighting the three-dimensional nature of the fungus gardens. Like crossing jungle vines, the ants must traverse a moat on aerial walkways to reach their foraging site. A few institutions use high-tech exhibitory to elucidate leaf-cutting ant behavior.
The Central Park Zoo in New York City placed miniature video cameras within nest tunnels to catch passing workers in action; highly magnified ants at work are shown live on large color viewing monitors. The Museum of Civilization in Quebec temporarily displayed leaf-cutting ants as part of a comprehensive exhibit on the history of communication. The multi-media exhibit focused primarily on the many diverse modes of human communication, but also explored alternatives employed by animals; leaf-cutting ants were chosen to illustrate chemical communication via pheromones. Fungus gardens were housed in futuristic boxes interconnected with zig-zagging runways, while interpretive text described the relationship between recruitment pheromones and the development of efficient foraging trails. The leaf-cutting ant colony was widely acclaimed to be the single most successful feature of the entire exhibit! The Smithsonian Institution's Insect Zoo in Washington D.C. displays A. texana, native only to Louisiana and Texas. This northern representative of the genus is unusual because it is polygynous, or tolerant of more than one mated queen within a colony. SASI has the distinction of being the only organization maintaining a naturally foraging observation colony of leaf-cutting ants. SASI works with Atta mexicana, a desert dwelling species native to Mexico and southern Arizona. At the SASI animal lab, leaf-cutting ant fungus gardens are established in a series of clear plastic containers, and joined to a large aquarium serving as an internal foraging area. As a precaution, the nest entrance is fitted with a queen excluder allowing only the free flow of workers, even though it is inconceivable that the queen would abandon the safety of the nest. The inner foraging area has a drawbridge leading to a passage through the wall to the desert outside. Since foraging workers return to the nest during intense mid-day heat, simply raising the drawbridge confines the colony for servicing. The leaf-cutting ant colony at SASI is available to students and scientists for school and research projects. Participants in SASI's educational programs and other visitors to SASI are able to view the intimate details of social life within the fungus gardens, and at the same time, observe workers foraging for plant material outside under natural conditions. While there are many interesting live arthropods and activities at SASI, the chance to watch the ants at work is alone worth the visit; don't miss this or any other opportunity to see the amazing leaf-cutting ants on parade!

REFERENCES & ADDITIONAL READING: DITMARS, R.L. (1938): A colony of parasol ants. New York Zoological Society Bulletin. Vol. xli, No. 6, pp. 183-188. HÖLLDOBLER, B. & E.O. WILSON. (1990): The Ants. Belknapp Press of Harvard University Press, Cambridge. 732 pp. LOFGREN, C.S. & R.L. VANDER MEER, Edit's. (1986): Fire Ants and Leaf-cutting ants, Biology and Management. Westview Press, Boulder and London. 435 pp. WEBER, N.A. (1972): Gardening Ants, the Attines. American Philosophical Society, Philadelphia. 146 pp. WEBER, N.A. (1982): Fungus Ants. In Social Insects, Vol. IV, H.R. Hermann, Edit., Academic Press, New York and London. pp: 255-363. WHEELER, W.M. (1973): The Fungus Growing Ants of North America. Dover Publications Inc., New York. 136+ pp. (originally published in 1907). WILSON, E.O. (1971): The Insect Societies. Belknapp Press of Harvard University Press, Cambridge, Mass. 548 pp. Bio: Randy Morgan is Headkeeper of the Cincinnati Zoo Insectarium. He has had a life-long interest in ant behavior and worked with SASI Director Steve Prchal to set up the naturally foraging leaf-cutting ant colony at SASI. The author thanks his wife, Kathy, for manuscript comments.