[3] What makes Polyergus special is the way a newly mated queen can, all by herself, take over a Formica nest and start a new colony.

The queen responds by biting with her sharp mandibles and releasing a pheromone from her enlarged Dufour's gland that, unlike many other parasitic ants, has a pacifying effect.

Specific to Polyergus, when the queen first enters a Formica nest she releases a pheromone from her enlarged Dufour’s gland.

Topoff did experiments to show that this pheromone has an important facilitative effect in colony usurpation; it reduces the aggression of the defending Formica workers.

The researchers took the Dufour’s, pygidial, and poison glands from freshly mated Polyergus queens, using water as a negative control.

Because it was impossible to prevent a Polyergus queen from secreting her own pheromones during a live encounter, they used the harvester ant Pogonomyrmex occidentalis (naturally attacked by Formica) as the subject.

That takeover can occur even if the host queen is dead, but not if she is not present, proves that chemical absorption is important.

[3] Considerable work has been published on the evolution of ant dulosis and almost all of it has at least some empirical evidence to defend its positions.

[6] In addition, about 100 years ago, Carlo Emery observed that, "The slave-making temporarily and permanently parasitic ants originate from closely related forms which serve them as host.

Rather than just relying solely on morphological cues, he used enzyme gel electrophoresis assays to create a detailed phylogenetic picture of host and parasite connections.

[8] The selective forces involved in the evolution of social parasitism are not fully understood, and it is unlikely that one model fits all relationships.

"Any hypothesis explaining the evolution of slavery in Polyergus must account both for the origin of group raiding with brood capture, and for non-independent colony foundation by queens".

[9] Topoff gives an adequate hypothesis to the evolution of Polyergus by integrating three processes: queen takeover, olfactory imprinting, and territorial fighting.

His previous work (which was presented earlier) shows what would have evolved for adaptation to occur: "(1) sharp mandibles for killing the Formica queen, (2) a pheromone that reduces aggression from resident workers, (3) a tendency to hold onto the dead Formica queen long enough to absorb her odors...".