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78-468: The Strepsiptera ( / s t r ɛ p ˈ s ɪ p t ər ə / ) are an order of insects with eleven extant families that include about 600 described species. They are endoparasites of other insects, such as bees , wasps , leafhoppers , silverfish , and cockroaches . Females of most species never emerge from the host after entering its body, finally dying inside it. The early-stage larvae do emerge because they must find an unoccupied living host, and

156-524: A change of developmental events (in which they differ from all the other pheromones, which trigger a change in behavior). They were first described in Schistocerca gregaria by Maud Norris in 1954. Signal pheromones cause short-term changes, such as the neurotransmitter release that activates a response. For instance, GnRH molecule functions as a neurotransmitter in rats to elicit lordosis behavior . The human trace amine-associated receptors are

234-537: A class of pheromone receptors involved in the olfactive detection of social cues. A review of studies involving non-human animals indicated that TAARs in the olfactory epithelium can mediate attractive or aversive behavioral responses to a receptor agonist . This review also noted that the behavioral response evoked by a TAAR can vary across species (e.g., TAAR5 mediates attraction to trimethylamine in mice and aversion to trimethylamine in rats). In humans, hTAAR5 presumably mediates aversion to trimethylamine, which

312-414: A group of six G protein-coupled receptors (i.e., TAAR1 , TAAR2 , TAAR5 , TAAR6 , TAAR8 , and TAAR9 ) that – with exception for TAAR1 – are expressed in the human olfactory epithelium . In humans and other animals, TAARs in the olfactory epithelium function as olfactory receptors that detect volatile amine odorants , including certain pheromones; these TAARs putatively function as

390-563: A hundred species, are marine. Insects such as snow scorpionflies flourish in cold habitats including the Arctic and at high altitude. Insects such as desert locusts , ants, beetles, and termites are adapted to some of the hottest and driest environments on earth, such as the Sonoran Desert . Insects form a clade , a natural group with a common ancestor, among the arthropods . A phylogenetic analysis by Kjer et al. (2016) places

468-442: A kind of carboxylic acid ) was found in female rhesus monkeys that produced six types in the vaginal fluids. The combination of these acids is referred to as "copulins". One of the acids, acetic acid, was found in all of the sampled female's vaginal fluid. Even in humans, one-third of women have all six types of copulins, which increase in quantity before ovulation. Copulins are used to signal ovulation; however, as human ovulation

546-506: A large number of stylopidians targeting wasps and bees, while the largest family of strepsipterans, the Stylopidae , with over 27% of all described strepsipterans, targets bees exclusively. Very rarely, multiple females may live within a single stylopized host; multiple males within a single host are somewhat more common. Strepsiptera of the family Myrmecolacidae can influence their host's behaviour , causing their ant hosts to linger on

624-417: A pest population with the corresponding parasitoid may sometimes aid in reducing the impact of such pests, although no strepsipterans have ever been tested for use in this capacity, let alone being available for such purposes, either commercially or experimentally. Insect Insects (from Latin insectum ) are hexapod invertebrates of the class Insecta . They are the largest group within

702-404: A pheromone to help find a female gamete for fertilization . Many well-studied insect species, such as the ant Leptothorax acervorum , the moths Helicoverpa zea and Agrotis ipsilon , the bee Xylocopa sonorina , the frog Pseudophryne bibronii , and the butterfly Edith's checkerspot release sex pheromones to attract a mate, and some lepidopterans (moths and butterflies) can detect

780-433: A potential mate from as far away as 10 km (6.2 mi). Some insects, such as ghost moths , use pheromones during lek mating . Traps containing pheromones are used by farmers to detect and monitor insect populations in orchards. In addition, Colias eurytheme butterflies release pheromones, an olfactory cue important for mate selection. In mealworm beetles, Tenebrio molitor , the female preference of pheromones

858-545: A pupa, developing through a series of increasingly adult-like nymphal stages. The higher level relationship of the insects is unclear. Fossilized insects of enormous size have been found from the Paleozoic Era, including giant dragonfly-like insects with wingspans of 55 to 70 cm (22 to 28 in). The most diverse insect groups appear to have coevolved with flowering plants . Adult insects typically move about by walking and flying; some can swim. Insects are

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936-447: A repellent pheromone, which causes avoidance behaviour in ants. Repellent trail markers may help ants to undertake more efficient collective exploration. The army ant Eciton burchellii provides an example of using pheromones to mark and maintain foraging paths. When species of wasps such as Polybia sericea found new nests, they use pheromones to lead the rest of the colony to the new nesting site. Gregarious caterpillars, such as

1014-607: A superficial resemblance to flies. The forewings are modified into small club-shaped structures called halteres , which sense gyroscopic information. A similar organ exists in flies, though in that group the hindwings are modified instead, and the two groups are thought to have independently evolved the structures. The hindwings are generally fan-shaped, and have strongly reduced venation . The antennae are flabellate , and are covered in specialised chemoreceptors , likely to detect females over long distances. Adult male Strepsiptera have eyes unlike those of any other insect , resembling

1092-418: A system of paired openings along their sides, connected to small tubes that take air directly to the tissues. The blood therefore does not carry oxygen; it is only partly contained in vessels, and some circulates in an open hemocoel . Insect vision is mainly through their compound eyes , with additional small ocelli . Many insects can hear, using tympanal organs , which may be on the legs or other parts of

1170-525: A variety of ways. Male moths can sense the pheromones of female moths over great distances. Other species communicate with sounds: crickets stridulate , or rub their wings together, to attract a mate and repel other males. Lampyrid beetles communicate with light. Humans regard many insects as pests , especially those that damage crops, and attempt to control them using insecticides and other techniques. Others are parasitic , and may act as vectors of diseases . Insect pollinators are essential to

1248-525: A volatile substance when attacked by a predator that can trigger flight (in aphids ) or aggression (in ants , bees , termites , and wasps ) in members of the same species. For example, Vespula squamosa use alarm pheromones to alert others to a threat. In Polistes exclamans , alarm pheromones are also used as an alert to incoming predators. Pheromones also exist in plants: Certain plants emit alarm pheromones when grazed upon, resulting in tannin production in neighboring plants. These tannins make

1326-521: A well sclerotised cephalothorax (fused head and thorax ). Adult female mengenillids are wingless but are free living and somewhat mobile with legs and small eyes. This is probably also true for the bahiaxenids, though this has not been observed. Newly hatched primary (first instar ) larvae are on average 230 micrometres ( 1 ⁄ 128  in) in length, smaller than many single-celled organisms. They are highly mobile with well developed stemmata , which are able to distinguish color. The underside of

1404-428: Is 2-pyrrolidinone . Epideictic pheromones are different from territory pheromones, when it comes to insects. Fabre observed and noted how "females who lay their eggs in these fruits deposit these mysterious substances in the vicinity of their clutch to signal to other females of the same species they should clutch elsewhere." It may be helpful to note that the word epideictic , having to do with display or show (from

1482-504: Is concealed it is thought that they may be used for reasons other than sexual communication. The human vomeronasal organ has epithelia that may be able to serve as a chemical sensory organ; however, the genes that encode the VNO receptors are nonfunctional pseudogenes in humans. Also, while there are sensory neurons in the human VNO there seem to be no connections between the VNO and the central nervous system. The associated olfactory bulb

1560-673: Is dependent on the nutritional condition of the males. The effect of Hz-2V virus infection on the reproductive physiology and behavior of female Helicoverpa zea moths is that in the absence of males they exhibited calling behavior and called as often but for shorter periods on average than control females. Even after these contacts virus-infected females made many frequent contacts with males and continued to call; they were found to produce five to seven times more pheromone and attracted twice as many males as did control females in flight tunnel experiments. Pheromones are also utilized by bee and wasp species. Some pheromones can be used to suppress

1638-454: Is in a deep narrow fissure of the cephalothorax near the birth canal). Sperm passes through the opening directly into the body in a process called traumatic insemination , which has independently evolved in some other insects like bed bugs . Strepsiptera eggs hatch inside the female, and the planidium larvae can move around freely within the female's haemocoel ; this behavior is unique to these insects. The offspring consume their mother from

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1716-443: Is known to act as an hTAAR5 agonist and to possess a foul, fishy odor that is aversive to humans; however, hTAAR5 is not the only olfactory receptor that is responsible for trimethylamine olfaction in humans. As of December 2015, hTAAR5-mediated trimethylamine aversion has not been examined in published research. In reptiles , amphibia and non-primate mammals pheromones are detected by regular olfactory membranes, and also by

1794-412: Is present in the fetus, but regresses and vanishes in the adult brain. There have been some reports that the human VNO does function, but only responds to hormones in a "sex-specific manner". There also have been pheromone receptor genes found in olfactory mucosa. There have been no experiments that compare people lacking the VNO, and people that have it. It is disputed on whether the chemicals are reaching

1872-404: Is the need for cleanliness and odorlessness in human participants. Though various researchers have investigated the possibility of their existence, no pheromonal substance has ever been demonstrated to directly influence human behavior in a peer reviewed study. Experiments have focused on three classes of possible human pheromones: axillary steroids, vaginal aliphatic acids, and stimulators of

1950-853: The Latin word insectum from in , "cut up", as insects appear to be cut into three parts. The Latin word was introduced by Pliny the Elder who calqued the Ancient Greek word ἔντομον éntomon "insect" (as in entomology ) from ἔντομος éntomos "cut in pieces"; this was Aristotle 's term for this class of life in his biology , also in reference to their notched bodies. The English word insect first appears in 1601 in Philemon Holland 's translation of Pliny. In common speech, insects and other terrestrial arthropods are often called bugs . Entomologists to some extent reserve

2028-2237: The Paraneoptera , and Kjer et al. 2016 for the Holometabola . The numbers of described extant species (boldface for groups with over 100,000 species) are from Stork 2018. Archaeognatha (hump-backed/jumping bristletails, 513 spp) [REDACTED] Zygentoma (silverfish, firebrats, fishmoths, 560 spp) [REDACTED] Odonata (dragonflies and damselflies, 5,899 spp) [REDACTED] Ephemeroptera (mayflies, 3,240 spp) [REDACTED] Zoraptera (angel insects, 37 spp) [REDACTED] Dermaptera (earwigs, 1,978 spp) [REDACTED] Plecoptera (stoneflies, 3,743 spp) [REDACTED] Orthoptera (grasshoppers, crickets, katydids, 23,855 spp) [REDACTED] Grylloblattodea (ice crawlers, 34 spp) [REDACTED] Mantophasmatodea (gladiators, 15 spp) [REDACTED] Phasmatodea (stick insects, 3,014 spp) [REDACTED] Embioptera (webspinners, 463 spp) [REDACTED] Mantodea (mantises, 2,400 spp) [REDACTED] Blattodea (cockroaches and termites, 7,314 spp) [REDACTED] Psocodea (book lice, barklice and sucking lice, 11,000 spp) [REDACTED] [REDACTED] Hemiptera (true bugs, 103,590 spp) [REDACTED] Thysanoptera (thrips, 5,864 spp) [REDACTED] Hymenoptera (sawflies, wasps, bees, ants, 116,861 spp) [REDACTED] Strepsiptera (twisted-wing flies, 609 spp) [REDACTED] Coleoptera (beetles, 386,500 spp) [REDACTED] Raphidioptera (snakeflies, 254 spp) [REDACTED] Neuroptera (lacewings, 5,868 spp) [REDACTED] Megaloptera (alderflies and dobsonflies, 354 spp) [REDACTED] Lepidoptera (butterflies and moths, 157,338 spp) [REDACTED] Trichoptera (caddisflies, 14,391 spp) [REDACTED] Diptera (true flies, 155,477 spp) [REDACTED] Mecoptera (scorpionflies, 757 spp) [REDACTED] Siphonaptera (fleas, 2,075 spp) [REDACTED] [REDACTED] [REDACTED] [REDACTED] [REDACTED] [REDACTED] [REDACTED] Pheromone The portmanteau word "pheromone"

2106-491: The arthropod phylum . Insects have a chitinous exoskeleton , a three-part body ( head , thorax and abdomen ), three pairs of jointed legs , compound eyes , and a pair of antennae . Insects are the most diverse group of animals, with more than a million described species ; they represent more than half of all animal species. The insect nervous system consists of a brain and a ventral nerve cord . Most insects reproduce by laying eggs . Insects breathe air through

2184-406: The crown group , but are all more closely related to modern strepsiperans than Protoxenos is. The finding of a parasitic first instar in the same deposit indicates that the parasitic lifestyle of the group has likely existed nearly unchanged for 100 million years, though their evolutionary history prior to this remains a mystery. The idea that mengellinids' targeting of zygentomans represents

2262-562: The femur . The larvae are very active as they only have a limited amount of time to find a host before they exhaust their energy reserves. These first- instar larvae have stemmata (simple, single-lens eyes). When the larvae latch onto a host, they enter it by secreting enzymes that soften the cuticle, usually in the abdominal region of the host. Some species have been reported to enter the eggs of hosts. Larvae of Stichotrema dallatorreanurn Hofeneder from Papua New Guinea were found to enter their orthopteran host's tarsus (foot). Once inside

2340-449: The forest tent caterpillar , lay down pheromone trails that are used to achieve group movement. In animals, sex pheromones indicate the availability of the female for breeding. Male animals may also emit pheromones that convey information about their species and genotype . At the microscopic level, a number of bacterial species (e.g. Bacillus subtilis , Streptococcus pneumoniae , Bacillus cereus ) release specific chemicals into

2418-399: The vomeronasal organ (VNO), or Jacobson's organ, which lies at the base of the nasal septum between the nose and mouth and is the first stage of the accessory olfactory system . While the VNO is present in most amphibia, reptiles, and non-primate mammals, it is absent in birds , adult catarrhine monkeys (downward facing nostrils, as opposed to sideways), and apes . An active role for

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2496-891: The vomeronasal organ , including this 2018 study claiming pheromones affect men's sexual cognition. Axillary steroids are produced by the testes , ovaries , apocrine glands, and adrenal glands . These chemicals are not biologically active until puberty when sex steroids influence their activity. The change in activity during puberty suggest that humans may communicate through odors. Several axillary steroids have been described as possible human pheromones: androstadienol , androstadienone , androstenol , androstenone , and androsterone . While it may be expected on evolutionary grounds that humans have pheromones, these three molecules have yet to be rigorously proven to act as such. Research in this field has suffered from small sample sizes, publication bias , false positives, and poor methodology. A class of aliphatic acids (volatile fatty acids as

2574-775: The Greek 'deixis'), has a different but related meaning in rhetoric, the human art of persuasion by means of words. Laid down in the environment, territorial pheromones mark the boundaries and identity of an organism's territory. Cats and dogs deposit these pheromones by urinating on landmarks that mark the perimeter of the claimed territory. In social seabirds, the preen gland is used to mark nests, nuptial gifts, and territory boundaries with behavior formerly described as ' displacement activity '. Social insects commonly use trail pheromones. For example, ants mark their paths with pheromones consisting of volatile hydrocarbons . Certain ants lay down an initial trail of pheromones as they return to

2652-994: The Halictophagidae are found on leafhoppers, treehoppers, and mole cricket hosts. Strepsipteran insects in the genus Xenos parasitize Polistes carnifex , a species of social wasps. These obligate parasites infect the developing wasp larvae in the nest and are present within the abdomens of female wasps when they hatch out. Here they remain until they thrust through the cuticle and pupate (males) or release infective first- instar larvae onto flowers (females). These larvae are transported back to their nests by foraging wasps. After: † Protoxenidae † Cretostylopidae † Phthanoxenidae † Mengeidae Bahiaxenidae Mengenillidae Corioxenidae Bohartillidae Halictophagidae Elenchidae † Protelencholacidae Myrmecolacidae Callipharixenidae Xenidae Stylopidae Some insects which have been considered pests may have strepsipteran endoparasites. Inoculation of

2730-623: The Hemiptera (true bugs), Lepidoptera (butterflies and moths), Diptera (true flies), Hymenoptera (wasps, ants, and bees), and Coleoptera (beetles), each with more than 100,000 described species. Insects are distributed over every continent and almost every terrestrial habitat. There are many more species in the tropics , especially in rainforests , than in temperate zones. The world's regions have received widely differing amounts of attention from entomologists. The British Isles have been thoroughly surveyed, so that Gullan and Cranston 2014 state that

2808-648: The ancestral ecology of the group as a whole has been considered questionable. The vast majority of living strepispterans are placed within the grouping Stylopidia, which includes the families Corioxenidae , Halictophagidae , Callipharixenidae , Bohartillidae , Elenchidae , Myrmecolacidae , Stylopidae , Protelencholacidae (extinct) and Xenidae . All Stylopidia have endoparasitic females having multiple genital openings. Two living families, Mengenillidae and Bahiaxenidae , are placed outside of this group, along with several extinct families. The Stylopidae have four-segmented tarsi and four- to six-segmented antennae, with

2886-499: The arrival of both sexes at a calling site and increase the density of conspecifics surrounding the pheromone source. Most sex pheromones are produced by the females; only a small percentage of sex attractants are produced by males. Aggregation pheromones have been found in members of the Coleoptera , Collembola , Diptera , Hemiptera , Dictyoptera , and Orthoptera . In recent decades, aggregation pheromones have proven useful in

2964-537: The basis of scent signals, which enables them to avoid mating with close relatives and minimizes deleterious inbreeding . In addition to mice, two species of bumblebee, in particular Bombus bifarius and Bombus frigidus , have been observed to use pheromones as a means of kin recognition to avoid inbreeding. For example, B. bifarius males display "patrolling" behavior in which they mark specific paths outside their nests with pheromones and subsequently "patrol" these paths. Unrelated reproductive females are attracted to

3042-450: The behavior of the recipient. For example, some organisms use powerful attractant molecules to attract mates from a distance of two miles or more. In general, this type of pheromone elicits a rapid response, but is quickly degraded. In contrast, a primer pheromone has a slower onset and a longer duration. For example, rabbit (mothers) release mammary pheromones that trigger immediate nursing behavior by their babies. Primer pheromones trigger

3120-456: The body and affect neurocircuits , including the autonomous nervous system with hormone or cytokine mediated physiological changes, inflammatory signaling, immune system changes and/or behavioral change in the recipient. They proposed the term to describe chemical signals from conspecifics that elicit innate behaviors soon after the German biochemist Adolf Butenandt had characterized

3198-407: The body is covered in minute hair-like structures (microtrichia), which allow the larvae to stick to wet surfaces via capillary action . At the back of the body are well developed large bristle-like cerci , which are attached to muscles, which allow the larvae to jump. The tarsal segment of their legs have structures which allow them to cling to their hosts. Later larval instars which develop inside

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3276-459: The body. Their sense of smell is via receptors, usually on the antennae and the mouthparts. Nearly all insects hatch from eggs . Insect growth is constrained by the inelastic exoskeleton, so development involves a series of molts . The immature stages often differ from the adults in structure, habit and habitat. Groups that undergo four-stage metamorphosis often have a nearly immobile pupa . Insects that undergo three-stage metamorphosis lack

3354-470: The brain through the VNO or other tissues. In 2006, it was shown that a second mouse receptor sub-class is found in the olfactory epithelium . Called the trace amine-associated receptors (TAAR), some are activated by volatile amines found in mouse urine, including one putative mouse pheromone. Orthologous receptors exist in humans providing, the authors propose, evidence for a mechanism of human pheromone detection. Although there are disputes about

3432-636: The clade Coleopterida . The most basal strepsipteran is the fossil Protoxenos janzeni discovered in Eocene aged Baltic amber , while the most basal living strepsipteran is Bahiaxenos relictus , the sole member of the family Bahiaxenidae . The earliest known strepsipteran fossils are those of Cretostylops engeli (Cretostylopdiae) and Kinzelbachilla ellenbergeri , Phthanoxenos nervosus and Heterobathmilla kakopoios (Phthanoxenidae), discovered in middle Cretaceous Burmese amber from Myanmar , around 99 million years old, which all lie outside

3510-462: The clade Mecopterida (containing the Diptera and Lepidoptera), but found no strong evidence for affinity with any other extant group. Study of their evolutionary position has been problematic due to difficulties in phylogenetic analysis arising from long branch attraction . Most modern molecular studies find strepsipterans as the sister group of beetles (Coleoptera), with both groups together forming

3588-464: The evolution of unicellular prokaryotes to multicellular eukaryotes , primordial pheromone signaling between individuals may have evolved to paracrine and endocrine signaling within individual organisms. Some authors assume that approach-avoidance reactions in animals, elicited by chemical cues, form the phylogenetic basis for the experience of emotions in humans. Mice can distinguish close relatives from more distantly related individuals on

3666-667: The eyes found in the trilobite group Phacopina . Instead of a compound eye consisting of hundreds to thousands of ommatidia , that each produce a pixel of the entire image, the strepsipteran eyes consist of only a few dozen "eyelets" that each produce a complete image. These eyelets are separated by cuticle and/or setae, giving the cluster eye as a whole a blackberry-like appearance. The females of Stylopidia, which includes 97% of all described strepsipteran species and all modern strepsipteran families except Mengenillidae and Bahiaxenidae , are not known to leave their hosts and are neotenic in form, lacking wings, legs, and eyes, but have

3744-439: The filamentous fungi Neurospora crassa and Mucor mucedo , the water mold Achlya ambisexualis , the aquatic fungus Allomyces macrogynus , the slime mold Dictyostelium discoideum , the ciliate protozoan Blepharisma japonicum and the multicellular green algae Volvox carteri . In addition, male copepods can follow a three-dimensional pheromone trail left by a swimming female, and male gametes of many animals use

3822-477: The first such chemical, bombykol , a chemically well-characterized pheromone released by the female silkworm to attract mates. Aggregation pheromones function in mate choice , overcoming host resistance by mass attack, and defense against predators. A group of individuals at one location is referred to as an aggregation, whether consisting of one sex or both sexes. Male-produced sex attractants have been called aggregation pheromones, because they usually result in

3900-606: The genus Stylops . The name of the order translates to "twisted wing", giving rise to other common names used for the order, twisted-wing insects and twisted-winged parasites . Adult males are rarely observed, although specimens may be lured using cages containing virgin females. Nocturnal specimens can also be collected at light traps. Males of the Strepsiptera have wings , legs , eyes , and antennae , though their mouthparts cannot be used for feeding. Many have mouthparts modified into sensory structures. The males bear

3978-479: The host are completely immobile. Virgin females release a pheromone which the males use to locate them. Mating in at least some species is polyandrous , where the female mates with more than one male. In the Stylopidia, the female's anterior region protrudes out between the segments of the host's abdomen. In all strepsipterans the male mates by rupturing the female's cuticle (in the case of Stylopidia, this

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4056-444: The host, they undergo hypermetamorphosis and transform into a less-mobile, legless larval form. They induce the host to produce a bag-like structure inside which they feed and grow. This structure, made from host tissue, protects them from the immune defences of the host. Larvae go through four more instars, and in each moult the older cuticle separates but is not discarded (" apolysis without ecdysis "), so multiple layers form around

4134-414: The human VNO in the detection of pheromones is disputed; while it is clearly present in the fetus it appears to be atrophied , shrunk or completely absent in adults. Three distinct families of vomeronasal receptors , putatively pheromone sensing, have been identified in the vomeronasal organ named V1Rs, V2Rs, and V3Rs. All are G protein-coupled receptors but are only distantly related to the receptors of

4212-406: The immune system. Milinski and colleagues found that the artificial odors that people chose are determined in part by their major histocompatibility complexes (MHC) combination. Information about an individual's immune system could be used as a way of "sexual selection" so that the female could obtain good genes for her offspring. Claus Wedekind and colleagues found that both men and women prefer

4290-608: The insects among the Hexapoda , six-legged animals with segmented bodies; their closest relatives are the Diplura (bristletails). Collembola (springtails) [REDACTED] Protura (coneheads) [REDACTED] Diplura (two-pronged bristletails) [REDACTED] Insecta (=Ectognatha) [REDACTED] The internal phylogeny is based on the works of Wipfler et al. 2019 for the Polyneoptera , Johnson et al. 2018 for

4368-415: The inside in a process known as haemocoelous viviparity . Each female produces many thousands of planidium larvae. The larvae emerge from the brood opening/canal on the female's head, which protrudes outside the host body. Larvae have legs and actively seek out new hosts. Their legs are partly vestigial in that they lack a trochanter , the leg segment that forms the articulation between the basal coxa and

4446-586: The larvae. Male larvae pupate after the last moult, but females directly become neotenous adults. The colour and shape of the host's abdomen may be changed and the host usually becomes sterile. The parasites then undergo pupation to become adults. Adult males emerge from the host bodies, while females stay inside. Females may occupy up to 90% of the abdominal volume of their hosts. Adult males are very short-lived, usually surviving less than five hours, and do not feed. Strepsiptera of various species have been documented to attack hosts in many orders, including members of

4524-412: The main olfactory system, highlighting their different role. Olfactory processing of chemical signals like pheromones exists in all animal phyla and is thus the oldest of the senses. It has been suggested that it serves survival by generating appropriate behavioral responses to the signals of threat, sex and dominance status among members of the same species. Furthermore, it has been suggested that in

4602-412: The management of many pests, such as the boll weevil ( Anthonomus grandis ), the pea and bean weevil ( Sitona lineatus , and stored product weevils (e.g. Sitophilus zeamais , Sitophilus granarius , and Sitophilus oryzae ). Aggregation pheromones are among the most ecologically selective pest suppression methods. They are non-toxic and effective at very low concentrations. Some species release

4680-460: The mechanisms by which pheromones function, there is evidence that pheromones do affect humans. Despite this evidence, it has not been conclusively shown that humans have functional pheromones. Those experiments suggesting that certain pheromones have a positive effect on humans are countered by others indicating they have no effect whatsoever. A possible theory being studied now is that these axillary odors are being used to provide information about

4758-402: The name "bugs" for a narrow category of " true bugs ", insects of the order Hemiptera , such as cicadas and shield bugs . Other terrestrial arthropods, such as centipedes , millipedes , woodlice , spiders , mites and scorpions , are sometimes confused with insects, since they have a jointed exoskeleton. Adult insects are the only arthropods that ever have wings, with up to two pairs on

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4836-402: The nest with food. This trail attracts other ants and serves as a guide. As long as the food source remains available, visiting ants will continuously renew the pheromone trail. The pheromone requires continuous renewal because it evaporates quickly. When the food supply begins to dwindle, the trail-making ceases. Pharaoh ants ( Monomorium pharaonis ) mark trails that no longer lead to food with

4914-554: The only invertebrates that can achieve sustained powered flight; insect flight evolved just once. Many insects are at least partly aquatic , and have larvae with gills; in some species, the adults too are aquatic. Some species, such as water striders , can walk on the surface of water. Insects are mostly solitary, but some, such as bees , ants and termites , are social and live in large, well-organized colonies . Others, such as earwigs , provide maternal care, guarding their eggs and young. Insects can communicate with each other in

4992-448: The orders Zygentoma (silverfish and allies), Orthoptera (grasshoppers, crickets) Blattodea (cockroaches), Mantodea (praying mantis), Heteroptera (bugs), Hymenoptera (wasps, ants and bees), and Diptera (flies). In the strepsipteran family Myrmecolacidae , the males parasitize ants, while the females parasitize Orthoptera. Members of Mengenillidae target Zygentoma exclusively, while Stylopidia targets only winged insects , with

5070-546: The pheromones deposited by males on these paths, and males that encounter these females while patrolling can mate with them. Other bees of the Bombus species are found to emit pheromones as precopulatory signals, such as Bombus lapidarius . Pheromones of certain pest insect species, such as the Japanese beetle , acrobat ant , and the spongy moth , can be used to trap the respective insect for monitoring purposes, to control

5148-537: The plants less appetizing to herbivores . An alarm pheromone has been documented in a mammalian species. Alarmed pronghorn , Antilocapra americana flair their white rump hair and exposes two highly odoriferous glands that releases a compound described having the odor "reminiscent of buttered popcorn". This sends a message to other pronghorns by both sight and smell about a present danger. This scent has been observed by humans 20 to 30 meters downwind from alarmed animals. The major odour compound identified from this gland

5226-475: The population by creating confusion, to disrupt mating, and to prevent further egg laying. Pheromones are used in the detection of oestrus in sows . Boar pheromones are sprayed into the sty , and those sows that exhibit sexual arousal are known to be currently available for breeding. 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

5304-535: The reproduction of many flowering plants and so to their ecosystems. Many insects are ecologically beneficial as predators of pest insects, while a few provide direct economic benefit. Two species in particular are economically important and were domesticated many centuries ago: silkworms for silk and honey bees for honey . Insects are consumed as food in 80% of the world's nations, by people in roughly 3000 ethnic groups. Human activities are having serious effects on insect biodiversity . The word insect comes from

5382-552: The sexual behavior of other individuals allowing for a reproductive monopoly – the wasp R. marginata uses this. With regard to the Bombus hyperboreus species, males, otherwise known as drones, patrol circuits of scent marks (pheromones) to find queens. In particular, pheromones for the Bombus hyperboreus, include octadecenol , 2,3-dihydro-6-transfarnesol, citronellol, and geranylcitronellol. Sea urchins release pheromones into

5460-413: The short-lived males must emerge to seek a receptive female in her host. They are believed to be most closely related to beetles , from which they diverged 300–350 million years ago, but do not appear in the fossil record until the mid- Cretaceous around 100 million years ago. The order is not well known to non-specialists, and the nearest they have to a common name is stylops , in reference to

5538-425: The sister group to the beetle families Meloidae and Ripiphoridae , which have similar parasitic development and forewing reduction. Early molecular research suggested their inclusion as a sister group to the flies , in a clade called Halteria, which have one pair of the wings modified into halteres, and failed to support their relationship to the beetles. Further molecular studies, however, suggested they are outside

5616-422: The surrounding media to induce the "competent" state in neighboring bacteria. Competence is a physiological state that allows bacterial cells to take up DNA from other cells and incorporate this DNA into their own genome, a sexual process called transformation. Among eukaryotic microorganisms, pheromones promote sexual interaction in numerous species. These species include the yeast Saccharomyces cerevisiae ,

5694-462: The surrounding water, sending a chemical message that triggers other urchins in the colony to eject their sex cells simultaneously. In plants, some homosporous ferns release a chemical called antheridiogen , which affects sex expression. This is very similar to pheromones. This classification, based on the effects on behavior, remains artificial. Pheromones fill many additional functions. Releaser pheromones are pheromones that cause an alteration in

5772-510: The third segment having a lateral process. The family Stylopidae may be paraphyletic . The Elenchidae have two-segmented tarsi and four-segmented antennae, with the third segment having a lateral process. The Halictophagidae have three-segmented tarsi and seven-segmented antennae, with lateral processes from the third and fourth segments. The Stylopidae mostly parasitize wasps and bees, the Elenchidae are known to parasitize Fulgoroidea , while

5850-527: The thorax. Whether winged or not, adult insects can be distinguished by their three-part body plan, with head, thorax, and abdomen; they have three pairs of legs on the thorax. Estimates of the total number of insect species vary considerably, suggesting that there are perhaps some 5.5 million insect species in existence, of which about one million have been described and named. These constitute around half of all eukaryote species, including animals , plants , and fungi . The most diverse insect orders are

5928-487: The tips of grass leaves, increasing the chance of being found by strepsipteran males (in the case of females) and putting them in a good position for male emergence (in the case of males). The order, named by William Kirby in 1813, is named for the hindwings , which are held at a twisted angle when at rest (from Greek στρέϕειν ( strephein ), to twist; and πτερόν ( pteron ), wing). The forewings are reduced to halteres . Strepsiptera were once believed to be

6006-525: The total of around 22,500 species is probably within 5% of the actual number there; they comment that Canada's list of 30,000 described species is surely over half of the actual total. They add that the 3000 species of the American Arctic must be broadly accurate. In contrast, a large majority of the insect species of the tropics and the southern hemisphere are probably undescribed. Some 30–40,000 species inhabit freshwater ; very few insects, perhaps

6084-533: Was coined by Peter Karlson and Martin Lüscher in 1959, based on the Greek φέρω phérō ('I carry') and ὁρμων hórmōn ('stimulating'). Pheromones are also sometimes classified as ecto-hormones. They were researched earlier by various scientists, including Jean-Henri Fabre , Joseph A. Lintner , Adolf Butenandt , and ethologist Karl von Frisch who called them various names, like for instance "alarm substances". These chemical messengers are transported outside of

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