The Breeder is a rachni Queen genetically engineered by the Reapers, which appears in the Attican Traverse: Krogan Team mission on Uttuku. The breeder only appears if the rachni queen was killed by Shepard on Noveria. Unlike the first rachni queen, the Breeder will prove untrustworthy if set free by Shepard, and result in the loss of the Arlakh Company of krogan as war assets.
The Breeder is entrenched deep within the tunnels on Uttuku, guarded by Reaper technology and barriers controlled by local nodes. It speaks through the mouths of the dead krogan scout team, many of whom are suspended on the walls by the same webbing encountered on the way into the central chamber.