Pheromone

Pheromone is a chemical signal released by an individual that influences the behavior or physiology of others of the same species. It is a subset of semiochemicals used for intraspecific communication, as opposed to allomones or kairomones that affect other species. Pheromones can convey information about mating status, territory, danger, or social structure.

Pheromones are categorized by the immediate nature of the response: releaser pheromones provoke rapid behavioral changes, such as mating or trail-following; primer pheromones induce longer-term physiological changes, including hormonal modulation. Sex pheromones attract mates, aggregation pheromones unify individuals, and alarm pheromones trigger defensive or avoidance reactions. In social insects, queen pheromones help regulate caste and reproduction.

Detection occurs through chemosensory systems. In many animals, pheromones are detected by the olfactory system and, in some vertebrates, by a vomeronasal organ. Receptor families such as odorant receptors and pheromone-specific receptors transduce signals to the brain, producing context-appropriate responses.

Across taxa, pheromone use is widespread: insects employ trail, sex, aggregation, and alarm pheromones; bees and wasps use queen pheromones; fish release pheromones to synchronize reproduction. The existence and effect of pheromones in humans remains debated, with some studies suggesting subtle influence but no consensus on a clear, universal pheromonal system.

Applications include pest management through pheromone traps and disruption of mating cycles, as well as research tools for studying animal behavior and chemical communication. The term pheromone specifically denotes a signal between individuals of the same species; chemicals that affect other species are referred to as allomones or kairomones, and those involved in broader chemical signaling are called semiochemicals.