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A kairomone (a
coinage Coinage may refer to: * Coins, standardized as currency * Neologism, coinage of a new word * '' COINage'', numismatics magazine * Tin coinage, a tax on refined tin * Protologism ''Protologism'' is a term coined in 2003 by the American literary ...
using the Greek καιρός ''opportune moment'', paralleling
pheromone A pheromone () is a secreted or excreted chemical factor that triggers a social response in members of the same species. Pheromones are chemicals capable of acting like hormones outside the body of the secreting individual, to affect the behavio ...
"kairomone, n.". OED Online. September 2012. Oxford University Press. http://www.oed.com/view/Entry/241005?redirectedFrom=kairomone (accessed 3 October 2012).) is a
semiochemical A semiochemical, from the Greek wiktionary:σημεῖον, σημεῖον (''semeion''), meaning "signal", is a chemical substance or mixture released by an organism that affects the behaviors of other individuals. Semiochemical communication c ...
, emitted by an organism, which mediates
interspecific interaction Symbiosis (from Greek , , "living together", from , , "together", and , bíōsis, "living") is any type of a close and long-term biological interaction between two different biological organisms, be it mutualistic, commensalistic, or parasit ...
s in a way that benefits an individual of another species which receives it and harms the emitter. This "eavesdropping" is often disadvantageous to the producer (though other benefits of producing the substance may outweigh this cost, hence its persistence over evolutionary time). The kairomone improves the fitness of the recipient and in this respect differs from an
allomone An allomone (from Ancient Greek ' "other" and pheromone) is a type of semiochemical produced and released by an individual of one species that affects the behaviour of a member of another species to the benefit of the originator but not the rec ...
(which is the opposite: it benefits the producer and harms the receiver) and a synomone (which benefits both parties). The term is mostly used in the field of
entomology Entomology () is the science, scientific study of insects, a branch of zoology. In the past the term "insect" was less specific, and historically the definition of entomology would also include the study of animals in other arthropod groups, such ...
(the study of insects). Two main ecological cues are provided by kairomones; they generally either indicate a food source for the receiver, or the presence of a
predator Predation is a biological interaction where one organism, the predator, kills and eats another organism, its prey. It is one of a family of common feeding behaviours that includes parasitism and micropredation (which usually do not kill th ...
, the latter of which is less common or at least less studied.


Predators use them to find prey

An example of this can be found in the
Ponderosa Pine ''Pinus ponderosa'', commonly known as the ponderosa pine, bull pine, blackjack pine, western yellow-pine, or filipinus pine is a very large pine tree species of variable habitat native to mountainous regions of western North America. It is the ...
tree (''Pinus ponderosa''), which produces a
terpene Terpenes () are a class of natural products consisting of compounds with the formula (C5H8)n for n > 1. Comprising more than 30,000 compounds, these unsaturated hydrocarbons are produced predominantly by plants, particularly conifers. Terpenes ...
called
myrcene Myrcene, or β-myrcene, is a monoterpene. A colorless oil, it occurs widely in essential oils. It is produced mainly semi-synthetically from '' Myrcia'', from which it gets its name. It is an intermediate in the production of several fragrances. ...
when it is damaged by the Western pine beetle. Instead of deterring the insect, it acts
synergistically Synergy is an interaction or cooperation giving rise to a whole that is greater than the simple sum of its parts. The term ''synergy'' comes from the Attic Greek word συνεργία ' from ', , meaning "working together". History In Christia ...
with aggregation pheromones which in turn act to lure more beetles to the tree. Specialist predatory beetles find
bark beetle A bark beetle is the common name for the subfamily of beetles Scolytinae. Previously, this was considered a distinct family (Scolytidae), but is now understood to be a specialized clade of the "true weevil" family (Curculionidae). Although the ...
s (their prey) using the pheromones the bark beetles produce. In this case the chemical substance produced is both a pheromone (communication between bark beetles) and a kairomone (eavesdropping). This was discovered accidentally when the predatory beetles and other enemies were attracted to insect traps baited with bark beetle pheromones. Pheromones of different kinds may be exploited as kairomones by receivers. The German wasp, ''
Vespula germanica ''Vespula germanica'', the European wasp, German wasp, or German yellowjacket, is a species of wasp found in much of the Northern Hemisphere, native to Europe, Northern Africa, and temperate Asia. It has spread and become well-established in ma ...
'', is attracted to a pheromone produced by male Mediterranean fruit flies (''
Ceratitis capitata ''Ceratitis capitata'', commonly known as the Mediterranean fruit fly or medfly, is a yellow-and-brown fly native to sub-Saharan Africa. It has no near relatives in the Western Hemisphere and is considered to be one of the most destructive frui ...
'') when the males gather for a
mating In biology, mating is the pairing of either opposite-sex or hermaphroditic organisms for the purposes of sexual reproduction. ''Fertilization'' is the fusion of two gametes. ''Copulation'' is the union of the sex organs of two sexually reproduc ...
display, causing the death of some. In contrast, it is the
alarm pheromone A pheromone () is a secreted or excreted chemical factor that triggers a social response in members of the same species. Pheromones are chemicals capable of acting like hormones outside the body of the secreting individual, to affect the behavi ...
(used to communicate the presence of a threat) of an ant (''
Iridomyrmex purpureus ''Iridomyrmex'' is a genus of ants called rainbow ants (referring to their blue-green iridescent sheen) first described by Austrian entomologist Gustav Mayr in 1862. He placed the genus in the subfamily Dolichoderinae of the family Formicida ...
'') that a
spider Spiders ( order Araneae) are air-breathing arthropods that have eight legs, chelicerae with fangs generally able to inject venom, and spinnerets that extrude silk. They are the largest order of arachnids and rank seventh in total species ...
predator is attracted to.


Prey use them to adjust to predators

Some prey make use of chemicals originating from predators, using these cues as an indicator of the level of predation risk and changing their
morphology Morphology, from the Greek and meaning "study of shape", may refer to: Disciplines * Morphology (archaeology), study of the shapes or forms of artifacts * Morphology (astronomy), study of the shape of astronomical objects such as nebulae, galaxies ...
if need be. Changes in morphology caused by predator presence is known as
predator-induced polyphenism A polyphenic trait is a trait for which multiple, discrete phenotypes can arise from a single genotype as a result of differing environmental conditions. It is therefore a special case of phenotypic plasticity. There are several types of polyphe ...
, and occurs across a variety of animals. For example, ''
Daphnia ''Daphnia'' is a genus of small planktonic crustaceans, in length. ''Daphnia'' are members of the order Anomopoda, and are one of the several small aquatic crustaceans commonly called water fleas because their saltatory swimming style resembl ...
cucullata'' show formation of "helmets" when exposed to predators or the water they have lived in. Their predators include cladocerans (such as ''
Leptodora ''Leptodora'' is a genus containing two species of large, nearly transparency and translucency, transparent Predation, predatory water fleas. They grow up to long, with two large antenna (biology), antennae used for swimming and a single compoun ...
kindtii'') and
larva A larva (; plural larvae ) is a distinct juvenile form many animals undergo before metamorphosis into adults. Animals with indirect development such as insects, amphibians, or cnidarians typically have a larval phase of their life cycle. ...
e of '' Chaoborus flavicans'', a
midge A midge is any small fly, including species in several families of non-mosquito Nematoceran Diptera. Midges are found (seasonally or otherwise) on practically every land area outside permanently arid deserts and the frigid zones. Some mid ...
. They respond to these kairomones by doubling the size of their helmets, a protective structure. These changes in morphology make them safer from predators.
Mice A mouse ( : mice) is a small rodent. Characteristically, mice are known to have a pointed snout, small rounded ears, a body-length scaly tail, and a high breeding rate. The best known mouse species is the common house mouse (''Mus musculus' ...
are instinctively afraid of the smell of their natural
predator Predation is a biological interaction where one organism, the predator, kills and eats another organism, its prey. It is one of a family of common feeding behaviours that includes parasitism and micropredation (which usually do not kill th ...
s, including cats and rats. This occurs even in laboratory mice that have been isolated from predators for hundreds of generations. When the chemical cues responsible for the
fear Fear is an intensely unpleasant emotion in response to perceiving or recognizing a danger or threat. Fear causes physiological changes that may produce behavioral reactions such as mounting an aggressive response or fleeing the threat. Fear ...
response were purified from cat saliva and rat urine, two homologous protein signals were identified: Fel d 4 ('' Felis domesticus'' allergen 4), the product of the cat ''Mup'' gene, and Rat n 1 (''
Rattus norvegicus ''Rattus'' is a genus of muroid rodents, all typically called rats. However, the term rat can also be applied to rodent species outside of this genus. Species and description The best-known ''Rattus'' species are the black rat (''R. rattus'') ...
'' allergen 1), the product of the rat ''Mup13'' gene. Mice are fearful of these
major urinary proteins Major urinary proteins (Mups), also known as α2u-globulins, are a subfamily of proteins found in abundance in the urine and other secretions of many animals. Mups provide a small range of identifying information about the donor animal, when dete ...
(Mups) even when they are made in bacteria, but mutant animals that are unable to detect the Mups show no fear of rats, demonstrating their importance in initiating fearful behaviour. It is not known exactly how Mups from different species initiate disparate behaviours, but mouse Mups and predator Mups have been shown to activate unique patterns of sensory neurons in the nose of recipient mice. This implies the mouse perceives them differently, via distinct neural circuits. The pheromone receptors responsible for Mup detection are also unknown, though they are thought be members of the
V2R receptor V, or v, is the twenty-second and fifth-to-last Letter (alphabet), letter in the Latin alphabet, used in the English alphabet, modern English alphabet, the alphabets of other western European languages and others worldwide. Its name in Englis ...
class.


Applications

Like pheromones (communication chemicals used within a species), kairomones can be utilized as an 'attracticide' to lure a pest species to a location containing
pesticide Pesticides are substances that are meant to control pests. This includes herbicide, insecticide, nematicide, molluscicide, piscicide, avicide, rodenticide, bactericide, insect repellent, animal repellent, microbicide, fungicide, and lampri ...
. However, they might also be used to lure desired species. Kairomones produced by the hosts of parasitic wasps have been used in an attempt to attract them and keep them around in crops where they reduce herbivory, but this could instead result in fewer attacks on the herbivous pest if the applied kairomone distracts them from finding real hosts. For example, studies have shown that kairomones are effective in attracting female African sugarcane borers to deposit eggs on dead leaf material. Recent discoveries have highlighted that predators are attracted to the odour of co-existing predators. Kairomones have been extensively studied, and some are in successful usage, in Florida's '' Anastrepha suspensa'' eradication zone in support of the
citrus ''Citrus'' is a genus of flowering plant, flowering trees and shrubs in the rue family, Rutaceae. Plants in the genus produce citrus fruits, including important crops such as Orange (fruit), oranges, Lemon, lemons, grapefruits, pomelos, and lim ...
, and various other
orchard An orchard is an intentional plantation of trees or shrubs that is maintained for food production. Orchards comprise fruit- or nut-producing trees which are generally grown for commercial production. Orchards are also sometimes a feature of ...
industries there.


See also

*
Chemical ecology A chemical substance is a form of matter having constant chemical composition and characteristic properties. Some references add that chemical substance cannot be separated into its constituent elements by physical separation methods, i.e., wit ...
*
Major urinary proteins Major urinary proteins (Mups), also known as α2u-globulins, are a subfamily of proteins found in abundance in the urine and other secretions of many animals. Mups provide a small range of identifying information about the donor animal, when dete ...
*
Polyphenism A polyphenic trait is a trait for which multiple, discrete phenotypes can arise from a single genotype as a result of differing environmental conditions. It is therefore a special case of phenotypic plasticity. There are several types of polyphe ...
*
Push–pull technology Push–pull may refer to: In electronic technology *Push–pull output, type of electronic circuit * Push–pull converter, in electronics, is a type of DC to DC converter that uses a transformer * Push–pull connector, an electronic cable conne ...


References

*Weber A. 1999. The importance of info chemicals and clone-specific phenotypic plasticity in Daphnia ecology. PhD thesis University of Utrecht, The Netherlands. . {{Wiktionary Chemical ecology Insect ecology Phytochemicals Semiochemicals