[1] Production of allomones is a common form of defense against predators, particularly by plant species against insect herbivores.
In addition to defense, allomones are also used by organisms to obtain their prey or to hinder any surrounding competitors.
Others alter the allomones to form pheromones or other hormones, and yet others adopt them into their own defensive strategies, for example by regurgitating them when attacked by an insectivorous insect.
A third class of allelochemical (chemical used in interspecific communication), synomones, benefit both the sender and receiver.
Disrupt normal host selection behaviour e.g. Repellents, suppressants, locomotory excitants.