Reproductive development and ontogeny of queen pheromone production in thefire ant Solenopsis invicta

Queens of the fire ant, Solenopsis invicta Buren, produce several releaser and primer pheromones. Using bioassays, the ontogeny of three of these pher omones related to reproductive development was investigated. Virgin queens, in which the process of wing-shedding (dealation) serves as an indicator o f the initiation of reproductive development, were studied. First, the prod uction of two queen pheromones produced in the poison gland was examined. T he pheromone responsible for initiation and maintenance of retinue formatio n, a releaser effect, was found to be produced in detectable quantities 2 d ays after dealation, at which time queens showed significant ovary developm ent and many (30%) had started laying eggs. A primer pheromone that inhibit s alate virgin queens from dealating was detected in queens 3 days followin g wing-shedding, when 80% of the queens were ovipositing. Second, I examine d the onset of a pheromone of unknown glandular origin produced by reproduc tively active virgin queens which leads to their destruction in queenright colonies by stimulating workers to attack and kill them. This pheromone is secreted in quantities detectable by bioassay 2 days after dealation. Thus, in S. invicta, the ontogeny of three distinct queen pheromones is tightly linked with ovary development and initiation of egg laying. These results d emonstrate reproductive and communicative functions are closely associated during the transition from potential to functional queen.