Pheromones Serving Functions Other than Reproduction
Besides sexual responses as described above pheromones mediate several other types of behaviour. Alarm pheromones have been found in termites and bees. The termite soldiers liberate alarm pheromones attracting (communicating alarm signals) the aggressive workers that participate in attacking the intrusive individuals. Trait pheromones secreted by insects help social integrity during migration of colonies by orienting along an invisible chemical trail that has been laid out by one or more conspecific insects. Both aerial land terrestrial trails are possible. Some species of ants and termites deploy trait pheromones in the recruitment of workers to food sources. Aggregate pheromones make it possible for both sexes to aggregate.
They are produced by members of both sexes. Pheromone-mediated aggregation helps to aggregate insects for feeding, protection, reproduction etc. A pheromone, 2-methoxy-5- ethylaphenol is produced from faeces of the migratory locust, Locusta migratoria migratorioides. The pheromone causes the young hoppers to aggregate and is also associated with the induction of morphological and physiological changes that result in the transformation of the hoppers to the migratory phase. In cockroaches also, the pheromones released from various surfaces of the body and from the faeces cause aggregation. In the protozoan Dictyostelium discoideum (amoebae, also known as cellular slime molds) the amoebae release pulses of a pheromone, which has been identified as cyclic 3'-5'AMP resulting in the aggregation.