Figure 2.

Diagram of a typical ant colony representing the six topics discussed in this review. (1) Morphological caste determination. In most ant species, a switch during larval development triggers alternative trajectories toward different female castes. Only the queen and one-worker caste are represented here, but some species also have different morphological worker castes. (2) Division of labor. Different groups of workers perform different tasks. Here, some workers nurse the brood inside the nest, whereas others forage for food outside. (3) Chemical communication. Ants rely on chemical communication for many aspects of their social organization. (4) Social immunity. Ants use both behavioral and physiological defenses to limit the transmission of pathogens and diseases in their societies. (5) Social structure. Ant species differ in the number of queens found in one nest, as well as the number of males that the queens mate with (not shown here). In some cases, these numbers vary between colonies of the same species. (6) Mutualism. Many ant species engage in mutualistic interactions with other organisms. Here, some ants tend and protect aphids in exchange for the sugary honeydew they produce.