Sex pheromone

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Sex pheromones are pheromones released by an organism to attract an individual of the same species, encourage them to mate with them, or perform some other function closely related with sexual reproduction. Sex pheromones specifically focus on indicating females for breeding, attracting the opposite sex, and conveying information on species, age, sex and genotype. Non-volatile pheromones, or cuticular contact pheromones, are more closely related to social insects as they are usually detected by direct contact with chemoreceptors on the antennae or feet of insects.

Contents

Insect sex pheromones have found uses in monitoring and trapping of pest insects.

Evolution

Sex pheromones have evolved in many species. The many types of pheromones (i.e. alarm, aggregation, defense, sexual attraction) all have a common cause acting as chemical cues to trigger a response. However, sex pheromones are particularly associated with signaling mating behaviors or dominance. The odors released can be seen as a favorable trait selected by either the male or female leading to attraction and copulation. Chemical signaling is also used to find genetically different mates and thus avoid inbreeding. [1] Females are often selective when deciding to mate, and chemical communication ensures that they find a high-quality mate that satisfies their reproductive needs.

Sexual selection

Females of the tiger moth Utetheisa ornatrix choose males that produce more pheromones. Utetheisa bella.jpg
Females of the tiger moth Utetheisa ornatrix choose males that produce more pheromones.
Common crow butterfly male (Euploea core) with hair pencils everted to disperse sex pheromone. Common crow butterfly male with hair pencils everted to disperse sex pheromone image by Sumita Roy DuttaDSCN0187.jpg
Common crow butterfly male (Euploea core) with hair pencils everted to disperse sex pheromone.

Odours may be a kind of male "ornament" selected for by female choice. They meet the criteria for such ornaments that Charles Darwin set out in The Descent of Man, and Selection in Relation to Sex . After many years of study the importance of such chemical communication is becoming clear. [3]

Males usually compete for scarce females, which make adaptive choices based on male traits. The choice can benefit the female directly and/or genetically. In tiger moths ( Utetheisa ornatrix ), females choose the males that produce the most pheromone; an honest signal of the amount of protective alkaloids the male has, as well as an indicator of the size of female offspring (females fertilised by such males lay more eggs). [3] Male cockroaches form dominance hierarchies based on pheromone "badges", while females use the same pheromone for male choice. [4]

In most species, pheromones are released by the non-limiting sex. Some female moths signal, but this is cheap and low risk; it means the male has to fly to her, taking a high risk. This mirrors communication with other sensory modalities, e.g. male frogs croak; male birds are usually colourful. Male long-range pheromone signals may be associated with patchy resources for the female. In some species, both sexes signal. Males can sometimes attract other males instead, the sex pheromone acting as an aggregation pheromone. [3]

External fertilization and chemical duets

It is likely that most externally fertilizing species (e.g. marine worms, sea urchins) coordinate their sexual behaviour (release of sperm and eggs) using pheromones. This coordination is very important because sperm are diluted easily, and are short-lived. Coordination therefore provides a selective advantage to both males and females: individuals that do not coordinate are unlikely to achieve fertilisation and hence to leave offspring. [3]

The main selective advantage of outcrossing is that it promotes the masking of deleterious recessive alleles, while inbreeding promotes their harmful expression. [5] [6]

In humans

No study has led to the isolation of true human sex pheromones. [7] [8] While humans are highly dependent upon visual cues, when in close proximity, smells also play a role in sociosexual behaviors. An inherent difficulty in studying human pheromones is the need for cleanliness and odorlessness in human participants. [9]

Signalling

Sexual development in the freshwater alga Volvox is triggered by tiny concentrations of a glycoprotein pheromone. Mikrofoto.de-volvox-8.jpg
Sexual development in the freshwater alga Volvox is triggered by tiny concentrations of a glycoprotein pheromone.

Different species use a wide variety of chemical substances to send sexual signals. The first to be described chemically was bombykol, the silkworm moth's sex pheromone, which is a complex alcohol, (E,Z)-10,12-hexadecadienol, discovered in 1959. It is detected in the antennae of the male moth by a pheromone-binding protein which carries the bombykol to a receptor bound to the membrane of a nerve cell. [10] The chemicals used by other moths are species-specific. For example, the Eastern spruce budworm Choristoneura fumiferana female pheromones contain a 95:5 mix of E- and Z 11-tetradecenal aldehydes, while the sex pheromones of other species of spruce budworm contain acetates and alcohols. [11]

Sexual development in the freshwater green alga Volvox is initiated by a glycoprotein pheromone. [12] It is one of the most potent known biological effector molecules, as it can trigger sexual development at a concentration as low as 10−16 moles per litre. [12] Kirk and Kirk showed that sex-inducing pheromone production can be triggered experimentally in somatic cells by heat shock. [13]

Uses

A pheromone trap in use to monitor insect pests Sesiidae Pheromon fg01.jpg
A pheromone trap in use to monitor insect pests

Sex pheromones have found applications in pest monitoring and pest control. For monitoring, pheromone traps are used to attract and catch a sample of pest insects to determine whether control measures are needed. For control, much larger quantities of a sex pheromone are released to disrupt the mating of a pest species. This can be either by releasing enough pheromone to prevent males from finding females, effectively drowning out their signals, or by mass trapping, attracting and removing pests directly. [14] For example, research on the control of the spruce bud moth ( Zeiraphera canadensis) has focused on the use of the pheromone E-9-tetradecenyl-acetate, a chemical the spruce bud moth releases during mating. [15]

Related Research Articles

<i>Volvox</i> Genus of algae

Volvox is a polyphyletic genus of chlorophyte green algae in the family Volvocaceae. It forms spherical colonies of up to 50,000 cells. They live in a variety of freshwater habitats, and were first reported by Antonie van Leeuwenhoek in 1700. Volvox diverged from unicellular ancestors approximately 200 million years ago.

Pheromone Secreted or excreted chemical factor that triggers a social response in members of the same species

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 behavior of the receiving individuals. There are alarm pheromones, food trail pheromones, sex pheromones, and many others that affect behavior or physiology. Pheromones are used by many organisms, from basic unicellular prokaryotes to complex multicellular eukaryotes. Their use among insects has been particularly well documented. In addition, some vertebrates, plants and ciliates communicate by using pheromones. The ecological functions and evolution of pheromones are a major topic of research in the field of chemical ecology.

<i>Helicoverpa zea</i> Species of moth

Helicoverpa zea, commonly known as the corn earworm, is a species in the family Noctuidae. The larva of the moth Helicoverpa zea is a major agricultural pest. Since it is polyphagous during the larval stage, the species has been given many different common names, including the cotton bollworm and the tomato fruitworm. It also consumes a wide variety of other crops.

Chemical ecology is the study of chemically-mediated interactions between living organisms, and the effects of those interactions on the demography, behavior and ultimately evolution of the organisms involved. It is thus a vast and highly interdisciplinary field. Chemical ecologists seek to identify the specific molecules that function as signals mediating community or ecosystem processes and to understand the evolution of these signals. The substances that serve in such roles are typically small, readily-diffusible organic molecules, but can also include larger molecules and small peptides.

Cabbage looper Species of moth

The cabbage looper is a medium-sized moth in the family Noctuidae, a family commonly referred to as owlet moths. Its common name comes from its preferred host plants and distinctive crawling behavior. Cruciferous vegetables, such as cabbage, bok choy, and broccoli, are its main host plant; hence, the reference to cabbage in its common name. The larva is called a looper because it arches its back into a loop when it crawls.

Bombykol Chemical compound

Bombykol is a pheromone released by the female silkworm moth to attract mates. It is also the sex pheromone in the wild silk moth. Discovered by Adolf Butenandt in 1959, it was the first pheromone to be characterized chemically.

A semiochemical, from the Greek σημεῖον (semeion), meaning "signal", is a chemical substance or mixture released by an organism that affects the behaviors of other individuals. Semiochemical communication can be divided into two broad classes: communication between individuals of the same species (intraspecific) or communication between different species (interspecific).

Lesser wax moth Species of moth

The lesser wax moth is a small moth of the snout moth family (Pyralidae) that belongs to the subfamily Galleriinae. The species was first described by Johan Christian Fabricius in 1794. Adults are about 0.5 inches (13 mm) in length and have a distinct yellow head with a silver-grey or beige body. Lesser wax moths are common in most parts of the world, except in areas with cold climates. Their geographic spread was aided by humans who inadvertently introduced them to many regions worldwide.

Diamondback moth Species of moth

The diamondback moth, sometimes called the cabbage moth, is a moth species of the family Plutellidae and genus Plutella. The small, grayish-brown moth sometimes has a cream-colored band that forms a diamond along its back. The species may have originated in Europe, South Africa, or the Mediterranean region, but it has now spread worldwide.

<i>Spodoptera litura</i> Species of moth

Spodoptera litura, otherwise known as the tobacco cutworm or cotton leafworm, is a nocturnal moth in the family Noctuidae. S. litura is a serious polyphagous pest in Asia, Oceania, and the Indian subcontinent that was first described by Johan Christian Fabricius in 1775. Its common names reference two of the most frequent host plants of the moth. In total, 87 species of host plants that are infested by S. litura are of economic importance. The species parasitize the plants through the larvae vigorous eating patterns, oftentimes leaving the leaves completely destroyed. The moth's effects are quite disastrous, destroying economically important agricultural crops and decreasing yield in some plants completely. Their potential impact on the many different cultivated crops, and subsequently the local agricultural economy, has led to serious efforts to control the pests.

<i>Choristoneura fumiferana</i> Species of moth

Choristoneura fumiferana, the eastern spruce budworm, is a species of moth of the family Tortricidae native to the eastern United States and Canada. The caterpillars feed on the needles of spruce and fir trees. Eastern spruce budworm populations can experience significant oscillations, with large outbreaks sometimes resulting in wide scale tree mortality. The first recorded outbreaks of the spruce budworm in the United States occurred in about 1807, and since 1909 there have been waves of budworm outbreaks throughout the eastern United States and Canada. In Canada, the major outbreaks occurred in periods circa 1910–20, c. 1940–50, and c. 1970–80, each of which impacted millions of hectares of forest. Longer-term tree-ring studies suggest that spruce budworm outbreaks have been recurring approximately every three decades since the 16th century, and paleoecological studies suggest the spruce budworm has been breaking out in eastern North America for thousands of years.

<i>Cimex</i> Genus of true bugs

Cimex is a genus of insects in the family Cimicidae. Cimex species are ectoparasites that typically feed on the blood of birds and mammals. Two species, Cimex lectularius and Cimex hemipterus, are known as bed bugs and frequently feed on humans, although other species may parasitize humans opportunistically. Species that primarily parasitize bats are known as bat bugs.

Mating disruption (MD) is a pest management technique designed to control certain insect pests by introducing artificial stimuli that confuse the individuals and disrupt mate localization and/or courtship, thus preventing mating and blocking the reproductive cycle. It usually involves the use of synthetic sex pheromones, although other approaches, such as interfering with vibrational communication, are also being developed.

<i>Aphomia sociella</i> Species of moth

Aphomia sociella, also known as the bee moth and the bumble bee wax moth, is a small moth of the family Pyralidae and subfamily Galleriinae. Its body and forewings are typically reddish brown, tan, or dark green in color and females have a dark spot in the center of each forewing. The bee moth is native to Europe and are named "bee moths" because they seek out nests of bees and wasps to lay their eggs. Aphomiasociella are considered a pest because the bee moth larvae severely damage commercial bee hives. Bee moths are also studied for their unique mating ritual which includes a release of pheromones from both the male and the female along with an ultrasonic signal emitted through the male's tymbals.

<i>Chloridea virescens</i> Species of moth

Chloridea virescens, commonly known as the tobacco budworm, is a moth of the family Noctuidae found throughout the eastern and southwestern United States along with parts of Central America and South America.

Pheromone trap Type of insect trap that uses pheromones to lure insects

A pheromone trap is a type of insect trap that uses pheromones to lure insects. Sex pheromones and aggregating pheromones are the most common types used. A pheromone-impregnated lure, as the red rubber septa in the picture, is encased in a conventional trap such as a bottle trap, Delta trap, water-pan trap, or funnel trap. Pheromone traps are used both to count insect populations by sampling, and to trap pests such as clothes moths to destroy them.

<i>Helicoverpa assulta</i> Species of moth

Helicoverpa assulta, the oriental tobacco budworm, is a moth of the family Noctuidae. H. assulta adults are migratory and are found all over the Old World Tropics including Asia, Africa, and Australia.

Odour is sensory stimulation of the olfactory membrane of the nose by a group of molecules. Certain body odours are connected to human sexual attraction. Humans can make use of body odour subconsciously to identify whether a potential mate will pass on favourable traits to their offspring. Body odour may provide significant cues about the genetic quality, health and reproductive success of a potential mate. Body odour affects sexual attraction in a number of ways including through human biology, the menstrual cycle and fluctuating asymmetry. The olfactory membrane plays a role in smelling and subconsciously assessing another human's pheromones. It also affects the sexual attraction of insects and mammals. The major histocompatibility complex genes are important for the immune system, and appear to play a role in sexual attraction via body odour. Studies have shown that body odor is strongly connected with attraction in heterosexual females. The women in one study ranked body odor as more important for attraction than “looks”. Humans may not simply depend on visual and verbal senses to be attracted to a possible partner/mate.

The pheromone biosynthesis activation neuropeptide (PBAN) is a neurohormone that activates the biosynthesis of pheromones in moths. Female moths release PBAN into their hemolymph during the scotophase to stimulate the biosynthesis of the unique pheromone that will attract the conspecific males. PBAN release is drastically reduced after mating, contributing to the loss in female receptivity. In Agrotis ipsilon, it has been shown that the Juvenile Hormone helps induce release of PBAN which goes on to influence pheromone production and responsiveness in females and males, respectively. In the Helicoverpa assulta, the circadian rhythm of pheromone production is closely associated with PBAN release.

<i>Ostrinia furnacalis</i> Species of moth

Ostrinia furnacalis is a species of moth in the family Crambidae, the grass moths. It was described by Achille Guenée in 1854 and is known by the common name Asian corn borer since this species is found in Asia and feeds mainly on corn crop. The moth is found from China to Australia, including in Java, Sulawesi, the Philippines, Borneo, New Guinea, the Solomon Islands, and Micronesia. The Asian corn borer is part of the species complex, Ostrinia, in which members are difficult to distinguish based on appearance. Other Ostrinia such as O. orientalis, O. scapulalis, O. zealis, and O. zaguliaevi can occur with O. furnacalis, and the taxa can be hard to tell apart.

References

  1. ↑ Bernstein, C., Bernstein, H. (1997). "Sexual communication". J. Theor. Biol. 188 (1): 69–78. doi:10.1006/jtbi.1997.0459. PMID   9299310.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  2. ↑ Howse, P.; Stevens, J.M.; Jones, Owen T. (2013). Insect Pheromones and their Use in Pest Management. Springer. p. 44. ISBN   978-94-011-5344-7.
  3. 1 2 3 4 Wyatt, T. (2003). Pheromones and Animal Behaviour . Cambridge University Press.[ page needed ]
  4. ↑ Moore, A.J.; Moore, P.J. (1999). "Balancing sexual selection through opposing mate choice and male competition". Proceedings of the Royal Society B: Biological Sciences. 266 (1420): 711–716. doi:10.1098/rspb.1999.0694. PMC   1689829 .
  5. ↑ Bernstein, H.; Hopf, F.A.; Michod, R.E. (1987). "The molecular basis of the evolution of sex". Adv Genet. Advances in Genetics. 24: 323–70. doi:10.1016/s0065-2660(08)60012-7. ISBN   9780120176243. PMID   3324702.
  6. ↑ Michod, R.E. (1994). Eros and Evolution: A Natural Philosophy of Sex . Addison-Wesley. ISBN   978-0201442328.
  7. ↑ Wysocki, Charles J.; Preti, George (7 October 2004). "Facts, fallacies, fears, and frustrations with human pheromones". The Anatomical Record. 281A (1): 1201–1211. doi: 10.1002/ar.a.20125 . PMID   15470677. It is emphasized that no bioassay-guided study has led to the isolation of true human pheromones, a step that will elucidate specific functions to human chemical signals.
  8. ↑ Riley, Alex (9 May 2016). "Pheromones are probably not why people find you attractive". BBC News. Retrieved 2016-05-09.
  9. ↑ Grammer, Karl; Fink, Bernhard; Neave, Nick (2005). "Human pheromones and sexual attraction". European Journal of Obstetrics and Gynecology and Reproductive Biology. 118 (2): 135–142. doi:10.1016/j.ejogrb.2004.08.010. PMID   15653193.
  10. ↑ Sandler, Benjamin H.; Nikonova, Larisa; Leal, Walter S.; Clardy, Jon (2000). "Sexual attraction in the silkworm moth: structure of the pheromone-binding-protein–bombykol complex". Chemistry & Biology. 7 (2): 143–151. doi: 10.1016/S1074-5521(00)00078-8 . PMID   10662696.
  11. ↑ Allison, Jeremy D.; Carde, Ring T. (2016). Pheromone Communication in Moths: Evolution, Behavior, and Application. University of California Press. pp. 265–271. ISBN   978-0520964433.
  12. 1 2 Hallmann, A.; Godl, K.; Wenzl, S.; Sumper, M. (1998). "The highly efficient sex-inducing pheromone system of Volvox". Trends Microbiol. 6 (5): 185–9. doi:10.1016/s0966-842x(98)01234-7. PMID   9614342.
  13. ↑ Kirk, D.L.; Kirk, M.M. (1986). "Heat shock elicits production of sexual inducer in Volvox". Science. 231 (4733): 51–4. Bibcode:1986Sci...231...51K. doi:10.1126/science.3941891. PMID   3941891.
  14. ↑ Foster, S. P.; Harris, M. O. (1997). "Behavioral Manipulation Methods for Insect Pest Management". Annual Review of Entomology. 42 (1): 123–146. doi:10.1146/annurev.ento.42.1.123. PMID   15012310.
  15. ↑ Turgeon, Jean J. (1992). "Status of research on the development of management tactics and strategies for the spruce bud moth in white spruce plantations". The Forestry Chronicle. 68 (5): 614–622. doi: 10.5558/tfc68614-5 .
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