Alarm Pheromones of Insects
Alarm pheromones are defined as chemical substances, produced and released by an organism, that warn or alert another of the same species of impending danger. This is exemplified by many species of aphids (Hemiptera: Aphididae) in which the pheromone is caused to be released by attack, for example, by predators, with ensuing dispersal by which individual aphids may avoid a subsequent attack. However, the term alarm pheromone also is employed when the responding individuals are stimulated to show aggression towards the attacking agent. This is common in the social Hymenoptera; for example, the honeybee, Apis mellifera (Hymenoptera: Apidae), and many ant species respond aggressively to their alarm pheromones.
As alarm pheromones can benefit the survival of members of the species involved, it is common for insects that employ alarm pheromones to live in congregations for some or all of their life cycle. In the case of social Hymenoptera, the colony is genetically