Kairomone
Encyclopedia
A kairomone is a semiochemical
, emitted by an organism, which mediates interspecific interactions in a way that benefits an individual of another species which receives it, without benefiting 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
(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
(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, the latter of which is less common or at least less studied.
tree (Pinus ponderosa), which produces a terpene
called myrcene when it is damaged by the Western pine beetle. Instead of deterring the insect, it acts synergistically with aggregation pheromones which in turn act to lure more beetles to the tree.
Specialist predatory beetles find bark beetle
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 is attracted to a pheromone produced by male Mediterranean fruit flies (Ceratitis capitata
) when lekking (a lek is a gathering of males for mating
display), causing the death of some. In contrast, it is the alarm pheromone (used to communicate the presence of a threat) of an ant (Iridomyrmex purpureus) that a spider
predator is attracted to.
if need be. Changes in morphology caused by predator presence is known as predator-induced polyphenism, and occurs across a variety of animals. For example Daphnia
cucullata show formation of "helmets" when exposed to predators or the water they have lived in. Their predators include cladocerans (such as Leptodora
kindtii) and larva
e of Chaoborus flavicans, a midge
. 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 are instinctively afraid of the smell of their natural predators, 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
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 allergen 1), the product of the rat Mup13 gene. Mice are fearful of these major urinary proteins
(Mups) even when they are made in bacteria, but mutant animals that are unable to detect the Mups shown 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 class.
. 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 less attacks on the herbivous pest if the applied kairomone distracts them from finding real hosts.
Semiochemical
A semiochemical is a generic term used for a chemical substance or mixture that carries a message. These chemicals acts as messengers within or between species...
, emitted by an organism, which mediates interspecific interactions in a way that benefits an individual of another species which receives it, without benefiting 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
Allomone
An allomone is any chemical substance 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 receiver...
(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
Entomology is the scientific study of insects, a branch of arthropodology...
(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, 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 PinePonderosa Pine
Pinus ponderosa, commonly known as the Ponderosa Pine, Bull Pine, Blackjack Pine, or Western Yellow Pine, is a widespread and variable pine native to western North America. It was first described by David Douglas in 1826, from eastern Washington near present-day Spokane...
tree (Pinus ponderosa), which produces a terpene
Terpene
Terpenes are a large and diverse class of organic compounds, produced by a variety of plants, particularly conifers, though also by some insects such as termites or swallowtail butterflies, which emit terpenes from their osmeterium. They are often strong smelling and thus may have had a protective...
called myrcene when it is damaged by the Western pine beetle. Instead of deterring the insect, it acts synergistically with aggregation pheromones which in turn act to lure more beetles to the tree.
Specialist predatory beetles find bark beetle
Bark beetle
A bark beetle is one of approximately 220 genera with 6,000 species of beetles in the subfamily Scolytinae. Traditionally, this was considered a distinct family Scolytidae, but now it is understood that bark beetles are in fact very specialized members of the "true weevil" family...
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 is attracted to a pheromone produced by male Mediterranean fruit flies (Ceratitis capitata
Ceratitis capitata
Ceratitis capitata, the Mediterranean fruit fly, or medfly for short, is a species of fruit fly capable of causing extensive damage to a wide range of fruit crops...
) when lekking (a lek is a gathering of males for mating
Mating
In biology, mating is the pairing of opposite-sex or hermaphroditic organisms for copulation. In social animals, it also includes the raising of their offspring. Copulation is the union of the sex organs of two sexually reproducing animals for insemination and subsequent internal fertilization...
display), causing the death of some. In contrast, it is the alarm pheromone (used to communicate the presence of a threat) of an ant (Iridomyrmex purpureus) that a spider
Spider
Spiders are air-breathing arthropods that have eight legs, and chelicerae with fangs that inject venom. They are the largest order of arachnids and rank seventh in total species diversity among all other groups of organisms...
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 morphologyMorphology (biology)
In biology, morphology is a branch of bioscience dealing with the study of the form and structure of organisms and their specific structural features....
if need be. Changes in morphology caused by predator presence is known as predator-induced polyphenism, and occurs across a variety of animals. For example Daphnia
Daphnia
Daphnia are small, planktonic crustaceans, between 0.2 and 5 mm in length. Daphnia are members of the order Cladocera, and are one of the several small aquatic crustaceans commonly called water fleas because of their saltatory swimming style...
cucullata show formation of "helmets" when exposed to predators or the water they have lived in. Their predators include cladocerans (such as Leptodora
Leptodora
Leptodora is a genus containing two species of large, nearly transparent predatory water fleas. They grow up to long, with two large antennae used for swimming and a single compound eye. The legs are used to catch other copepods that it comes into contact with by chance...
kindtii) and larva
Larva
A larva 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
Midge
A midge is a very small, two-winged flying insect. "Midge" may also refer to:-Real:* Midge Costanza , American politician* Mildred Gillars , aka "Midge", American broadcaster of Nazi propaganda during World War II...
. 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 are instinctively afraid of the smell of their natural predators, 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
Fear is a distressing negative sensation induced by a perceived threat. It is a basic survival mechanism occurring in response to a specific stimulus, such as pain or the threat of danger...
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 allergen 1), the product of the rat Mup13 gene. Mice are fearful of these major urinary proteins
Major urinary proteins
Major urinary proteins , 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 detected by the vomeronasal organ of the receiving animal. They...
(Mups) even when they are made in bacteria, but mutant animals that are unable to detect the Mups shown 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 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 pesticidePesticide
Pesticides are substances or mixture of substances intended for preventing, destroying, repelling or mitigating any pest.A pesticide may be a chemical unicycle, biological agent , antimicrobial, disinfectant or device used against any pest...
. 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 less attacks on the herbivous pest if the applied kairomone distracts them from finding real hosts.
See also
- Chemical ecologyChemical ecologyChemical ecology is the study of the chemicals involved in the interactions of living organisms. It focuses on the production of and response to signaling molecules and toxins. Chemical ecology is of particular importance among ants and other social insects – including bees, wasps, and termites –...
- Major urinary proteinsMajor urinary proteinsMajor urinary proteins , 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 detected by the vomeronasal organ of the receiving animal. They...
- PolyphenismPolyphenismA polyphenic trait is a trait for which multiple, discrete phenotypes can arise from a single genotype as a result of differing environmental conditions.-Definition:A polyphenism is a biological mechanism that causes a trait to be polyphenic...
- Push–pull technology