Summertime means projects. In this case, a game about leafcutter ants.
Atta is a neotropical and subtropical genus of ants, of which Atta cephalotes is the most common. Workers collect bits of leaves, bring them back to the nest, and grow fungus gardens which are their primary source of protein.
Each ant species cultivates a different fungal species (from the family Lepiotaceae) which can survive only when tended by ants; hence the relationship between the ants and the fungus is a mutualism: without one of the species partners, the other cannot survive. When a queen Atta leaves the nest of her birth to start a new colony, she carries in her mouth bits of her home fungus with which to inoculate a new garden after she mates and digs a new nest.
As seen below right, Atta workers are continuously polymorphous, with their body size varying by more than an order of magnitude. Their tasks vary depending on the worker size. For example, the largest workers, which can be described as soldiers, protect the nest from predators.
Normally when a nest is active, one sees workers of all sizes milling about the mound. But one entertaining experience I had was walking onto a quiet Atta colombica mound in Costa Rica and stomping my feet. Suddenly I was surrounded by swarms of soldier ants, but none others.
In contrast, the smallest workers, referred to as “minims,” are often seen riding the leaves being carried by the leaf-cutting workers (which are generally of medium size). It was suggested by Feener and Moss (1990) that the job these tiny ants are doing is to protect the leaf-carrying ant from parasitism by flies (Phoridae). The flies must alight on the leaf carried by the worker to lay an egg on her, and the minims can prevent this.
It turns out that A. colombica, at least, does not limit itself to leaves for the substrate of its fungus garden. During the dry season in Costa Rica when there are abundant flowers available from flowering trees, they provide an acceptable resource too, and in fact one encounters thick trails of leaf cutter ants in colors different from the usual green (below right).
Because flowers are an ephemeral, and thus at some point a novel resource for the ants, some of us on a tropical biology course conducted an experiment to see whether the ants preferred more familiar or more novel substrate resources. It turned out that foragers definitely preferred substrates that they had encountered before (Howard et al., 1996); this makes sense because some leaves are toxic to the fungus and the ants learn this and avoid those species (Howard et al., 1988). If a a particular species of leaf or flower was successful at growing fungus, it makes sense that the ants would prefer that species over a novel one whose effectiveness is unclear.
That gives some background on this interesting group of ants. And now, for the game, “Atta Girl!”
Anyone who is familiar with the game “The Settlers of Catan” will get the gist of the rules for this board game. Below is the board in play:
The game is loosely based on the needs of leafcutter ant colonies, but some of the rules are more generalized for ants. The four colors used for the players are the main colors of ants that you will see: black, red, yellow (to represent strongly nocturnal ants such as the Mexican honeypot ant which can be very pale straw colored) and green (for weaver ants in Australia). (Atta themselves are mainly reddish brown, so a bit of artistic license was necessary here.)
These are the resources:
There is a bit of a fudge factor here. While for many ants, aphids and other homopterans serve as a useful sugar source (their prodigious excrement is loaded with sugars because they are mainly sucking sap for amino acids, which are in much lower concentration), generally leafcutter ants feed on leaf sap or, in the case of flower-collecting, on nectar.
Because the leaves are a resource necessary for growing the fungus, these are more tightly coupled than other resources in the game. There are extra leaves tiles but only one fungus tile on the board, but at all times three leaves cards can be exchanged for a fungus.
Below are the other costs of construction:
“Tunnels” are built with plastic ants. Players then establish chambers (with a nest hole) for one point, and mounds for two points. Plastic ants represent tunnels, and two “longest tunnel” victory points apply.
Available “colony cards” are these:
Some will be familiar. Rove beetles (Staphylinidae) can have special relationships with ants. Many live in ant nests; they can be a benign presence, or a pest that eats brood. They would not block resource procurement by Atta per se, in reality in the case of Atta they are probably mainly scavengers in their refuse piles. But for ants in general, they are useful as a proxy for an interfering nuisance. The usual two victory points are available to the player who plays the most rove beetle cards.
Kleptoparasites steal resources from other species. In the case of Atta, flies in the family Milichiidae may serve this role (Moser and Neff, 1971).
Two of the colony cards are particular to “Atta Girl!” The “male ants” card is a negative for the player who draws it. This is a bit of a joke that will be understood by those who know a lot about social Hymenoptera (social bees, ants, and wasps). These species are essentially matriarchal. The colony is run by the queen(s) and workers who are all female. The only function of males in social Hymenoptera is to provide sperm to the queens; they do no work around the colony before their mating flight, but just tend to get in the way of workers trying to do their jobs. So, we added that element to the game.
Finally, there is a special card that allows the player to draw two more colony cards immediately, and accept the good or bad consequences.
So, the game is not only fun but teaches a little bit about ant biology, as the players compete to see whose colony will collect the most resources and dominate. We’re sorry it’s not available commercially, but it was a lot of fun to make!
D. H. Feener Jr., K. A.G. Moss, 1990. Defense against parasites by hitchhikers in leaf-cutting ants: a quantitative assessment. Behavioral Ecology and Sociobiology 26(1):17-29
Howard, J. J., Cazin Jr, J., & Wiemer, D. F. (1988). Toxicity of terpenoid deterrents to the leafcutting ant Atta cephalotes and its mutualistic fungus.Journal of chemical ecology, 14(1), 59-69.
Howard, J. J., Henneman, M. L., Cronin, G., Fox, J. A., & Hormiga, G. 1996. Conditioning of scouts and recruits during foraging by a leaf-cutting ant, Atta colombica. Animal Behaviour, 52(2), 299-306.
Moser, J. C., & Neff, S. E. 1971. Pholeomyia comans (Diptera: Milichiidae) an associate of Atta texana: larval anatomy and notes on biology. Zeitschrift für angewandte Entomologie, 69(1?4), 343-348.