Slave-making ant

Slave-making ants are brood parasites that capture broods of other ant species to increase the worker force of their colony. After emerging in the slave-maker nest, slave workers work as if they were in their own colony, while parasite workers only concentrate on replenishing the labor force from neighboring host nests, a process called slave raiding.

The slave-making ants are specialized to parasitize a single species or a group of related species, and they are often close relatives to their hosts, which is typical for social parasites. The slave-makers may either be permanent social parasites (thus depending on enslaved ants throughout their whole lives) or facultative slave-makers. The behavior is unusual among ants but has evolved several times independently.

Theft of brood for the purpose of employing the stolen individual's efforts in support of the thief is called dulosis (from Greek doulos, "slave"), but the term "slave-making" is used in older literature and is still common. Herbers (2007) considered the term offensive and suggested "slave-making ants" be replaced with "pirate ants", noting that pirates take captives and rely on forced labor. Furthermore, "slave" could be replaced with "captive" and "dulosis" with "leistic behavior" (Greek for pirated spoils, leistos).

A related type of social parasitism is called inquilinism, in which a reproductive enters a host colony, lays eggs, and relies on the host colony to rear its offspring. Unlike brood parasitism, the inquiline remains within the nest and typically its brood does not outnumber the host's brood.

Slave-making ants may either be permanent social parasites, thus depending on enslaved hosts ants throughout their whole lives or facultative slave-makers. Facultative slave-making ants, like those in the Formica sanguinea complex, represent an intermediate parasitic group, between free-living species and obligatory slave-making species. In laboratory tests, when slaves were removed from colonies of Formica sanguinea and Polyergus rufescens, the behavior of F. sanguinea changed dramatically within 30 days of slave removal, with workers becoming self-sufficient at feeding and brood care. Workers of Polyergus, in contrast, were unable to care for their brood, and experienced high mortality.

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