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Pheromone

Pheromone

Pheremones are chemical signals released by an organism that influence the behavior of another. Communication between living cells is often ultimately chemical in nature. Chemical substances produced by one cell travel to another cell where they bind to protein receptors in the cell membrane or within the interior of the cell and initiate a series of signal transduction mechanisms that elicit a response. Chemicals that travel within an organism between cells of its own body are variously termed paracrines, neurotransmitters , neuromodulators, or hormones . Pheromones are chemicals that are carried between individual organisms of the same species. The response of the receiving organism is usually a change in its physiology or behavior.

Pheromones are often involved in the mating behavior between males and females in which the chemical serves as an attractant for one of the sexes. Following emergence from the cocoon, female Cecropia moths crawl a short distance away and broadcast a pheromone early in the morning that serves as an attractant for flying males. Males have olfactory ("smell") receptors on their antennae and they fly upwind and orient themselves to equalize the signals received by the two antennae. In this way, they can locate a virgin female from several miles away. Females of closely related species may use the same or a similar chemical but broadcast it at different times of the day. Males are genetically programmed to respond only at the appropriate time.

The female nearly always produces pheromones that serve as sex attractants, but males may produce pheromones that serve as aphrodisiacs. Mantispids are small predaceous insects that resemble miniature praying mantids. Courtship behavior is elaborate because the male must convince the female that he is a potential mate rather than an easy meal. The male produces a sweet musklike substance from his abdomen that helps to appease the female and reduce her predatory instincts.

Pheromones may be involved in mating even when the organisms do not actually meet. Many marine creatures such as sea urchins and oysters release eggs and sperm in the water in a process called spawning. Pheromones in these secretions will induce other members of the same species to simultaneously release their eggs or sperm, thereby increasing the likelihood that external fertilization will occur.

The preceding examples have involved pheromones carried in the air or water, but direct contact between the receiving organism and the pheromone must sometimes occur. Ants finding a source of food will lay down a trail with a secretion from their Dufour's gland by touching their abdomen to the ground as they return to the colony. Foragers leaving the colony can follow the pheromone trail back to the food source.

Sometime a pheromone can be "decoded" by another species and used against the animal that normally responds to it. The bolas spider twirls a silken thread tipped with a glob of sticky silk that it throws at insect prey to entrap them. The strand is coated with the same pheromone produced by certain female moths to attract males of their own species. When the amorous moths fly to the spider expecting to mate, they are instead captured and eaten.

see also Chemoreception; Hormones; Insect; Sexual Reproduction; Synaptic Transmission

Kurt Redborg

Bibliography

Chapman, Reginald F. The Insects: Structure and Function, 4th ed. Cambridge: Cambridge University Press, 1998.

Sumich, James L. An Introduction to the Biology of Marine Life. Dubuque, IA: William C. Brown, 1996.

Wilson, E. O. The Insect Societies. Cambridge, MA: Belknap Press, 1971.

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pheromones

pheromones like hormones, are secretions that act as chemical signals. While hormones change the behaviour of target cells elsewhere in the body, pheromones are odours that ‘carry stimulation’ (from the Greek phero and horma) and change the behaviour of other creatures of the same species that pick up the scent. Pheromones are widespread in the animal world, from the single-celled amoeba to human beings. A classic example is the pheromone emitted by female gypsy moths, which can be detected by sensory receptors on the antennae of a male moth 1 Km or more away, enabling it to home in on the female. Unspayed female dogs can attract males from a similar distance. Ants have a ‘lexicon’ of different pheromones, which they use to elicit attacks on or flight from predators, to mark trails, and so on. Territorial mammals often mark their territory with pheromones in their urine, or rubbed on to ‘scenting posts’ from glands in their skin. There seems to be genetically determined variation of pheromones among individuals of some species, enabling them to recognize mates, offspring or intruders on their territory. Although humans appear to have lost much of the olfactory sensitivity of their mammalian ancestors, recent research suggests that body odours, not necessarily consciously perceived, play an important role in social interaction. Human sweat acquires a distinctive odour at puberty, but urine, as well as genital secretions, may also contain pheromones. The well-known synchronization of the menstrual cycles of nuns and girls at boarding school is probably mediated by odour, and there is evidence that smell enables mothers to distinguish their own children's clothing from that worn by others. Sexual preference is certainly influenced by smell: love may indeed be largely a matter of ‘chemistry’.

Colin Blakemore


See also body odour; taste and smell.

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pheromones

pheromones, any of a variety of substances, secreted by many animal species, that alter the behavior of individuals of the same species. Sex attractant pheromones, secreted by a male or female to attract the opposite sex, are widespread among insects. The pheromones produced by males include a substance produced by cockroaches that attracts females and orients them in the correct mating positions and a substance elaborated by the desert locust that accelerates sexual maturation in adults of both sexes. Male-attracting pheromones have been discovered in the females of many species of beetles, bees, and moths. The polyphemus moth will not mate unless red oak leaves are present; it has been found that the leaves give off a volatile aldehyde that stimulates the female to release a male-attracting pheromone. Attempts are being made to use pheromones in insect control, e.g., as bait to attract males to field traps or, in very high concentrations, to disorient insects and prevent mating.

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pheromone

pheromone (ectohormone) A chemical substance (see semiochemical) emitted by an organism into the environment as a specific signal to another organism, usually of the same species. Pheromones play an important role in the social behaviour of certain animals, especially insects and mammals. They are used to attract mates, to mark trails, and to promote social cohesion and coordination in colonies (see queen substance). Pheromones are usually highly volatile organic acids or alcohols and can be effective at minute concentrations.

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pheromone

pher·o·mone / ˈferəˌmōn/ • n. Zool. a chemical substance produced and released into the environment by an animal, esp. a mammal or an insect, affecting the behavior or physiology of others of its species. DERIVATIVES: pher·o·mo·nal / ferəˈmōnl/ adj.

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pheromone

pheromone A chemical substance, produced and released into the environment by an animal, which then elicits a physiological and/or behavioural response in another individual of the same species. For example, pheromones are released by a variety of glands on the abdomen, head, and wings of insects.

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pheromone

pheromone A chemical substance, produced and released into the environment by an animal, which then elicits a physiological and/or behavioural response in another individual of the same species. For example, pheromones are released by a variety of glands on the abdomen, head and wings of insects.

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pheromone

pheromone Substance secreted externally by certain animals that influences the behaviour of members of the same species. Common in mammals and insects, these substances are often sexual attractants. They may be a component of body products such as urine, or secreted by specific glands.

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pheromone

pheromonealone, atone, Beaune, bemoan, blown, bone, Capone, clone, Cohn, Cologne, condone, cone, co-own, crone, drone, enthrone, flown, foreknown, foreshown, groan, grown, half-tone, home-grown, hone, Joan, known, leone, loan, lone, moan, Mon, mown, ochone, outflown, outgrown, own, phone, pone, prone, Rhône, roan, rone, sewn, shown, Simone, Sloane, Soane, sone, sown, stone, strown, throne, thrown, tone, trombone, Tyrone, unbeknown, undersown, zone •Dione • backbone • hambone •breastbone • aitchbone •tail bone, whalebone •cheekbone • shin bone • hip bone •wishbone • splint bone • herringbone •thigh bone • jawbone • marrowbone •knuckle bone • collarbone •methadone • headphone • cellphone •heckelphone • payphone • Freefone •radio-telephone, telephone •videophone • francophone •megaphone • speakerphone •allophone • Anglophone • xylophone •gramophone • homophone •vibraphone • microphone •saxophone • answerphone •dictaphone •sarrusophone, sousaphone •silicone • pine cone • snow cone •flyblown • cyclone • violone •hormone • pheromone • Oenone •chaperone • progesterone •testosterone

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Pheromone

Pheromone


Pheromones are chemicals released by an animal that have some sort of effect on another animal. They are used to communicate or pass a signal to another animal. They will provoke either an immediate response or a more generalized and longer-lasting one. Both types are intended to affect or to modify the behavior of another animal.

Unlike hormones, which are described as chemical messengers inside the body of an animal, pheromones are part of the exocrine system. This system releases chemical signals outside the body. Hormones are used internally and are one way an organism's body systems communicate and cooperate. Pheromones are exactly the opposite. Although they are chemical signals, they are used only outside of the body and are intended to communicate something to another animal. While hormones have as their object certain "target cells" inside the body that they seek out for a response, pheromones have other organisms as their target.

In terms of the amount of energy an organism uses by communicating this way, a chemical communication system is highly efficient. The animal usually uses substances that it already produces as waste or debris. Like hormones, pheromones are powerful and are highly effective in small amounts. Another reason that animals use pheromones or chemical signals is that these convey stable and simple signals. The message they contain is easily understood and often remains around for quite some time. Chemicals can also carry information in the dark.

Pheromones are usually intended only for other animals of the same species. They are often released by animals into their environment in the form of urine or sweat. They may also be passed from one animal to another by glands in the skin. Pheromones are classified in two major categories: primers or signalers (also called releasers).

PRIMING PHEROMONES

Priming pheromones are not used often. These cause a long-term response in the body of another animal that later influences how it behaves. An example of this is a female moth who releases an airborne chemical mixture. The mixture causes male moths of her species who are downwind to fly toward her (sometimes from as far away as 4 miles [6.44 meters]). As a result, the male moths change their behavior and keep flying upwind until they reach the female.

SIGNALING PHEROMONES

The more common signaling pheromones result in an immediate response, such as fear or aggression. An animal leaving its scent markers on its territory is an example of the use of signaling pheromones. Aside from these broad categories of pheromones, pheromones can also be grouped according to the type of behavior they provoke and by the role they play for a certain species.

BEHAVIORAL PHEROMONES

Pheromones can stimulate or deter (stop or prevent) a certain behavioral response such as egg-laying. Pheromones can also attract an animal to seek out the source of the chemical as some males do when they are get the scent of a female who is ready to mate. Other pheromones can repel or warn animals away from the source (as a territorial urine marker would do). Pheromones can serve as sexual or courtship chemicals to attract mates. Aggregation pheromones serve to attract other members of the species to the same spot, as when ants lay down a chemical trail for other ants to guide them to a food source.

Animals that are social and live in groups may release pheromones for defensive purposes in order to alert the band to some danger. Territorial, or marking, pheromones serve to communicate the boundaries of an animal's territory to others and to warn others to keep out. Finally, pheromones are an important means of regulating the behavior of individuals in a group. Studies have shown that when the odor of a male mouse is introduced among a group of female mice, the female's reproductive cycles become synchronized. It also is thought that humans release pheromones, but that they are mostly unaware of them.

[See alsoExcretory System ]

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Pheromones

Pheromones

Pheromones are very reactive (volatile) chemical compounds secreted by insects and animals that act as chemical signals between individuals. The pheromone-mediated signals influence physiology and behavior in a manner similar to hormones.

Pheromones are important to a variety of behaviors including mate attraction, territorality, trail marking, danger alarms, and social recognition and regulation.

The term pheromone is derived from the Greek words pheran (to transfer) and horman (to excite). In animals, they are produced in special glands and are released through body fluids, including saliva and perspiration. Most pheromones are biogenetically derived blends of two or more chemicals that must be emitted in exact proportions to be biologically active.

There is a remarkable diversity in the three-dimensional chemistry (stereochemistry) of pheromones. Insects are sensitive to and utilize slightly differing chemical structures to sharpen the perception of pheromone messages. The configurations of pheromones are critical. For example, while one configuration of a pheromone can trigger a reaction, another configuration of the molecule can inhibit the reaction.

Pheromones are found throughout the insect world. They are active in minute amounts. In fact, the pheromones released by some female insects such as the silkworm moth are recognized by the male of the species as far as a mile away. The pheromone secreted by the female gypsy moth can be detected by the male in concentrations as low as one molecule of pheromone in 1x1OI7 molecules of air. Insects detect pheromones with specialized chemosensory organs.

Another common example of pheromones in action is the trailing behavior of ants. Scout ants release pheromones that guide other ants to the location of food. In boars, pheromones found in boar saliva are known to cause the female to assume a mating position.

An increasingly important use of pheromones involves the control of insects. Because insects rely on phermomones, these compounds have been used by farmers as a method to control harmful insects. Using insect sex attractant pheromones, scientists have been able to produce highly specific traps and insecticides.

Pheromone traps are used to control the insects such as the European corn borer that damages millions of dollars of crops each year. The European corn borer larvae feed on and bore into the corn plant. Cavities produced by borers reduce the strength of the corn and interfere with plant physiology, including the translocation of water and nutrients. European corn borer pheromone traps contain a substance that mimics (i.e., acts like) a part of the chemical communication system used by female moths when they are receptive to mating. Male moths are attracted to and captured by the pheromone trap that is coated with a sticky substance that retains attracted insects.

Pheromones even influence human sexual behavior. The search for human aphrodisiacs (stimulants to sexual response) is as old as human history. Although the scientific evidence with regard to human pheromones is contradictory and highly debatable, pheromones are often used as an olfactory aphrodisiac in fragrances and perfumes.

One of the first human pheromones to be discovered were molecules called copulins, which exist in the vaginal secretion of women. At the time of their discovery, it was believed that these compounds could stimulate male sexual response. They were thought to work like their chemical counterparts excreted by monkeys, baboons, and chimpanzees. Other compounds implicated as pheromones have been discovered in human perspiration and urine. Still other compounds appear to function in the regulation and synchronization of the human female menstrual cycle.

The organ responsible for detecting pheromones in animals including humans is a chemosensory structure in the nose called the vomeronasal organ (VNO). The cells that up the VNO transmit a signal to the hypothalamus in the brain. The stimulating effect on the hypothalamus results in the production of proteins that may influence behavior.

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Learn more about citation styles

Citation styles

Encyclopedia.com gives you the ability to cite reference entries and articles according to common styles from the Modern Language Association (MLA), The Chicago Manual of Style, and the American Psychological Association (APA).

Within the “Cite this article” tool, pick a style to see how all available information looks when formatted according to that style. Then, copy and paste the text into your bibliography or works cited list.

Because each style has its own formatting nuances that evolve over time and not all information is available for every reference entry or article, Encyclopedia.com cannot guarantee each citation it generates. Therefore, it’s best to use Encyclopedia.com citations as a starting point before checking the style against your school or publication’s requirements and the most-recent information available at these sites:

Modern Language Association

http://www.mla.org/style

The Chicago Manual of Style

http://www.chicagomanualofstyle.org/tools_citationguide.html

American Psychological Association

http://apastyle.apa.org/

Notes:
  • Most online reference entries and articles do not have page numbers. Therefore, that information is unavailable for most Encyclopedia.com content. However, the date of retrieval is often important. Refer to each style’s convention regarding the best way to format page numbers and retrieval dates.
  • In addition to the MLA, Chicago, and APA styles, your school, university, publication, or institution may have its own requirements for citations. Therefore, be sure to refer to those guidelines when editing your bibliography or works cited list.

Pheromones

Pheromones

Pheromones are volatile chemical compounds secreted by insects and animals. They act as chemical signals between individuals influencing physiology and behavior in a manner similar to hormones . Pheromones are important to a variety of behaviors including mate attraction, territorality, trail marking, danger alarms, and social recognition and regulation.

The term pheromone is derived from the Greek words pheran (to transfer) and horman (to excite). In animals, they are produced in special glands and are released through body fluids, including saliva and perspiration. Most pheromones are biogenetically derived blends of two or more chemicals that must be emitted in exact proportions to be biologically active.

There is a remarkable diversity in the stereochemistry of pheromones. Insects are sensitive to and utilize chirality to sharpen the perception of pheromone messages. The configurations of pheromones are critical. Stereoisomers of pheromones, for example, can also be inhibitors of the pheromone action.

Pheromones are found throughout the insect world. They are active in minute amounts. In fact, the pheromones released by some female insects (e.g., Silkworm Moth) are recognized by the male of the species as far as a mile away. The pheromone secreted by the female gypsy moth can be detected by the male in concentrations as low as one molecule of pheromone in 1x1Oi7 molecules of air. Insects detect pheromones with specialized chemosensory organs.

At close range, pheromones continue to be released dictating specific behaviors. Another common example of pheromones in action is the trailing behavior of ants . Scout ants release pheromones that guide other ants to the location of food. In boars, pheromones found in boar saliva are known to cause the female to assume a mating position.

An increasingly important use of pheromones involves the control of insects. Because insects rely on phermomones, these compounds have been used by farmers as a method to control harmful insects. Using insect sex attractant pheromones, scientists have been able to produce highly specific traps and insecticides .

Pheromone traps are used to control the insects such as the European corn borer that damages millions of dollars of crops each year. The European corn borer larvae feed on and bore into the corn plant . Cavities produced by borers reduce the strength of the corn and interfere with plant physiology, including the translocation of water and nutrients . European corn borer pheromone traps contain a substance that mimics (i.e., acts like) a part of the chemical communication system used by female moths when they are are receptive to mating. Male moths are attracted to and captured by the pheromone trap that is coated with a sticky substance that retains attracted insects.

Research continues on insect pheromones. It is assumed that these compounds hold the key to developing insecticides that can kill only harmful insects while being harmless to humans and beneficial insects.

The search for human aphrodisiacs (stimulants to sexual response) is as old as human history. Although the scientific evidence with regard to human pheromones is contradictory and highly debatable, pheromones are often used as an olfactory aphrodisiac in fragrances and perfumes.

The first discovery related to human pheromones was reported the early 1970s. At this time low molecular weight aliphatic acids, called copulins, were found in the vaginal secretion of women. At the time, it was believed that these compounds could stimulate male sexual response. They were thought to work as did their chemical counterparts excreted by monkeys , baboons , and chimpanzees . In the late 1970s, more alleged human pheromones were discovered in human perspiration and urine. Some studies suggest a role for pheromones in the regulation and synchronization of the human female menstrual cycle .

The organ responsible for detecting pheromones in animals is a chemosensory structure in the nose called the vomeronasal organ (VNO). In lower animals, this organ detects substances that mediate sexual and territorial behaviors in species. It was once generally believed that humans did not have a VNO. Embryological texts asserted that this organ disappeared during embryonic development. In the 1980s, however, investigations refuted this alleged disappearance. Subsequent research suggested that a functioning VNO was present in near two small holes on the hard divider in the nose. A group of cells similar to nerve cells are located behind these holes. These cells, which make up the VNO, transmit a signal to the hypothalamus in the brain . The stimulating effect on the hypothalamus results in the production of proteins that may influence behavior.

See also Aerosols; Biochemistry; Biological rhythms; Smell.

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Pick a style below, and copy the text for your bibliography.

  • MLA
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"Pheromones." The Gale Encyclopedia of Science. . Encyclopedia.com. 21 Sep. 2018 <http://www.encyclopedia.com>.

"Pheromones." The Gale Encyclopedia of Science. . Encyclopedia.com. (September 21, 2018). http://www.encyclopedia.com/science/encyclopedias-almanacs-transcripts-and-maps/pheromones

"Pheromones." The Gale Encyclopedia of Science. . Retrieved September 21, 2018 from Encyclopedia.com: http://www.encyclopedia.com/science/encyclopedias-almanacs-transcripts-and-maps/pheromones

Learn more about citation styles

Citation styles

Encyclopedia.com gives you the ability to cite reference entries and articles according to common styles from the Modern Language Association (MLA), The Chicago Manual of Style, and the American Psychological Association (APA).

Within the “Cite this article” tool, pick a style to see how all available information looks when formatted according to that style. Then, copy and paste the text into your bibliography or works cited list.

Because each style has its own formatting nuances that evolve over time and not all information is available for every reference entry or article, Encyclopedia.com cannot guarantee each citation it generates. Therefore, it’s best to use Encyclopedia.com citations as a starting point before checking the style against your school or publication’s requirements and the most-recent information available at these sites:

Modern Language Association

http://www.mla.org/style

The Chicago Manual of Style

http://www.chicagomanualofstyle.org/tools_citationguide.html

American Psychological Association

http://apastyle.apa.org/

Notes:
  • Most online reference entries and articles do not have page numbers. Therefore, that information is unavailable for most Encyclopedia.com content. However, the date of retrieval is often important. Refer to each style’s convention regarding the best way to format page numbers and retrieval dates.
  • In addition to the MLA, Chicago, and APA styles, your school, university, publication, or institution may have its own requirements for citations. Therefore, be sure to refer to those guidelines when editing your bibliography or works cited list.