But some invaders manage to slip in with ease, none more mystifyingly
than the ant nest beetle.
Adult beetles stride into an ant colony in search of a mate, without
being harassed. They lay eggs, from which larva hatch. As far as
scientists can tell, workers feed the young beetles as if they were
When the beetles grow into adults, the ants swarm around them,
grooming their bodies. In exchange for this hospitality, the beetles
sink their jaws into ant larvae and freshly moulted adults in order to
drink their body fluids.
Social organisms are superentities. Where they exist they dominate. A good evolutionary strategy for an creature which is not of the social organism's species is to ingratiate itself into the society of the social organism, benefitting from its protection and resources.
This is what the Asari do. They are nest parasites of intelligent social species. Their "attractiveness" is interpreted as sexual by humans but is something more primal - it is an induced perception of desirability or charisma which makes members of social species feel like the Asari individual should be a valued part of the society or family or mate group. Much in the way the ant nest beetles are perceived by the ants.
Social insects are bound together with sound and smell cues. For intelligent social species (which would be all spacefaring species) it would not be surprising that the neural mechanisms which hold together social species might have evolved convergently, and so all be susceptible to the same mechanisms the Asari evolved to trick the social species they evolved with on their homeward.
The prediction: intelligent asocial creatures (a rarity I would think) would be immune to the Asari. But synthetic social species might not.
The question - why would Asari reproduce in the company of a member of the social species? If a member of the parasitized social species accepts the Asari as a mate, that means he or she has been well and truly tricked. The hustle is effective and that Asari individual is safely ensconced in a social nest. Resources and protection will therefore be available to the next generation as well, and with those things ensured it is a good time to reproduce.