Kairomones

Kairomones are chemical signals emitted by one species that are detected by individuals of a different species, providing a fitness advantage to the receiver while not necessarily benefiting the emitter. In this interspecific context, the receiver gains information that helps locate food, mates, or habitat, whereas the emitter may suffer a cost or gain no advantage from the signal. This concept is contrasted with pheromones, which mediate communication within the same species; allomones, which benefit the emitter but harm the receiver; and synomones, which benefit both parties.

Common examples and contexts include: carbon dioxide and host-related odors emitted by animals or plants that attract blood-feeding insects such as mosquitoes; herbivore-induced plant volatiles released when leaves are damaged by caterpillars or other herbivores that can recruit parasitoids or predators to the herbivores’ location; and various aquatic and terrestrial interactions where predators or parasites exploit chemical cues released by injured or stressed organisms. While kairomones can originate from hosts, prey, or damaged tissue, their ecological role remains that they convey information advantageous to the receiver, even if the emitter is disadvantaged.

Ecological significance and applications: kairomones shape foraging, host-seeking, and mating behaviors and can drive coevolutionary dynamics between species. In agriculture and pest management, kairomones are exploited to develop lure-and-kill or push-pull strategies by attracting pests to traps or by drawing natural enemies to crops. The effectiveness of kairomones depends on environmental conditions and the reliability of the cue in natural settings.