Alate Semiochemicals Release Worker Behavior During Fire Ant Nuptial Flights

Bioassays conducted during induced laboratory mating flights of Solenopsis invicta Buren investigated whether alate semiochemicals stimulate formation of the worker retinues that accompany alates during the preflight stage. In paired tests comparing worker response to alates vs response to other workers, workers preferentially entered, searched and recruited nestmates to vials that contained either an alate corpse or alate residue. Olfactory cues of both males and gynes (but not workers) attracted workers, induced alarm - recruitment, and promoted alate retrieval. Workers responding to these cues in our bioassays exhibited recruitment behavior previously unreported for fire ants, i.e., “back - and - forth jerking” and “group recruitment.” We propose that the observed worker behavior is a response to alate mandibular gland - derived alarm pheromone modulated by less volatile caste recognition cues associated with the alate cuticle.