|Peacock mite (Tuckerella sp.), false color SEM, magnified 260×|
|Cladistically included but traditionally excluded taxa|
Mites are small arthropods belonging to the class Arachnida and the subclass Acari (also known as Acarina). The term "mite" refers to the members of several groups in Acari but it is not a clade as it spans two different groups of arachnids; it also excludes the ticks, order Ixodida. Mites and ticks are characterised by the body being divided into two regions, the cephalothorax or prosoma (there is no separate head), and an opisthosoma. The scientific discipline devoted to the study of ticks and mites is called acarology.
Most mites are tiny, less than 1 mm (0.04 in) in length, and have a simple, unsegmented body plan. Their small size makes them easily overlooked; some species live in water, many live in soil as decomposers, others live on plants, sometimes creating galls, while others again are predators or parasites. This last group includes the commercially important Varroa parasite of honey bees, as well as the scabies mite of humans. Most species are harmless to humans but a few are associated with allergies or may transmit diseases.
The mites are not an exact taxon, but the name is used for members of several groups in the subclass Acari. The phylogeny of the Acari has been relatively little studied, but molecular information from ribosomal DNA is being extensively used to understand relationships between groups. The 18 S rRNA gene provides information on relationships among phyla and superphyla, while the ITS2, and the 18S ribosomal RNA and 28S ribosomal RNA genes, provide clues at deeper levels.
Most fossil acarids are no older than the Tertiary (up to 65 mya). Earlier fossils are too few to enable mite phylogeny to be reconstructed from palaeontological evidence, but in 2002 an oribatid mite (Brachypylina) from the Early Ordovician (c. 480 mya) was found in Oland, Sweden. The first find of Parasitiformes from the Mesozoic was of an argasid tick larva in Cretaceous amber (90–94 mya) from New Jersey. Other fossils including the first opilioacariform mite are preserved in Baltic amber of Eocene age (44 mya).
Members of the superorders Opilioacariformes and Acariformes (sometimes known as Actinotrichida) are mites, as well as some of the Parasitiformes (sometimes known as Anactinotrichida). Recent genetic research has caused a change in the naming scheme, however, and recent publications have changed the superorder Parasitiformes to an order. Other recent research has suggested that Acari is polyphyletic (of multiple origins), with ticks and spiders more closely related than ticks and mites. The cladogram is based on Dabert et al 2010, which used molecular data. It shows the Acariformes sister to the Solifugae (camel spiders), while the Parasitiformes are sister to the Pseudoscorpionida.
(mites and ticks)
Mites are tiny members of the class Arachnida; most are in the size range 250 to 750 μm (0.01 to 0.03 in) but some are larger and some are no bigger than 100 μm (0.004 in) as adults. The body plan is similar to that of ticks in having two regions, a cephalothorax (with no separate head) or prosoma, and an opisthosoma or abdomen. Segmentation has almost entirely been lost and the prosoma and opisthosoma are fused, only the positioning of the limbs indicating the location of the segments.
At the front of the body is the gnathosoma or capitulum. This is not a head and does not contain the eyes or the brain, but is a retractable feeding apparatus consisting of the chelicerae, the pedipalps and the oral cavity. It is covered above by an extension of the body carapace and is connected to the body by a flexible section of cuticle. The mouthparts differ between taxa depending on diet; in some species the appendages resemble legs while in others they are modified into chelicerae-like structures. The oral cavity connects posteriorly to the mouth and pharynx.
Most mites have four pairs of legs, each with six segments, which may be modified for swimming or other purposes. The dorsal surface of the body is clad in hardened tergites and the ventral surface by hardened sclerites; sometimes these form transverse ridges. The gonopore (genital opening) is located on the ventral surface between the fourth pair of legs. Some species have one to five median or lateral eyes but many species are blind, and slit and pit sense organs are common. Both body and limbs bear setae (bristles) which may be simple, flattened, club-shaped or sensory. Mites are usually some shade of brown, but some species are red, orange, black or green, or some combination of these colours.
Mites have a typical arachnid digestive system, although some species lack an anus: they do not defecate during their short lives. The circulatory system consists of a network of sinuses and lacks a heart, movement of fluid being driven by the contraction of body muscles. Gas exchange is carried out across the body surface, but many species additionally have between one and four pairs of tracheae, the spiracles being located in the front half of the body. The excretory system includes a nephridium and one or two pairs of Malpighian tubules.
The sexes are separate in mites; males have a pair of testes in the mid-region of the body, each connected to the gonopore by a vas deferens, and in some species there is a chitinous penis; females have a single ovary connected to the gonopore by an oviduct, as well as a seminal receptacle for the storage of sperm. In most mites, sperm is transferred to the female indirectly; the male either deposits a spermatophore on a surface from which it is picked up the female, or he uses his chelicerae or third pair of legs to insert it into the female's gonopore. In some of the Acariformes, insemination is direct using the male's penis.
The eggs are laid in the substrate, or wherever the mite happens to live. They take from two to six weeks to hatch, and the first stage larvae have six legs. After three moults, the larvae become nymphs, with eight legs, and after a further three moults, they become adults. Longevity varies between species, but the lifespan of mites is short as compared to many other arachnids.
Mites occupy a wide range of ecological niches. For example, Oribatida mites are important decomposers in many habitats. They eat a wide variety of material including living and dead plant and fungal material, lichens and carrion; some are predatory, though no oribatid mites are parasitic. Mites are among the most diverse and successful of all invertebrate groups. They have exploited a wide array of habitats, and because of their small size go largely unnoticed. They are found in fresh and salt water, in the soil, in forests, pastures, agricultural crops, ornamental plants, thermal springs and caves. They inhabit organic debris of all kinds and are extremely numerous in leaf litter. They feed on animals, plants and fungi and some are parasites of plants and animals. Some 48,200 species of mites have been described, but there may be a million or more species as yet undescribed. The tropical species Archegozetes longisetosus is one of the strongest animals in the world, relative to its mass (100 μg): It lifts up to 1,182 times its own weight, over five times more than would be expected of such a minute animal. A mite also holds a speed record: for its length, Paratarsotomus macropalpis is the fastest animal on Earth.
Many mites are parasitic on plants and animals. One family of mites, Pyroglyphidae, or nest mites, live primarily in the nests of birds and animals. These mites are largely parasitic and consume blood, skin and keratin. Dust mites, which feed mostly on dead skin and hair shed from humans instead of consuming them from the organism directly, evolved from these parasitic ancestors.
Parasitic mites sometimes infest insects. Varroa destructor attaches to the body of honey bees, and Acarapis woodi (family Tarsonemidae) lives in their tracheae. Hundreds of species are associated with other bees, mostly poorly described. They attach to bees in a variety of ways. For example, Trigona corvina workers have been found with mites attached to the outer face of their hind tibiae. Some are thought to be parasites, while others are beneficial symbionts. Mites also parasitize some ant species, such as Eciton burchellii.
Plant pests include the so-called spider mites (family Tetranychidae), thread-footed mites (family Tarsonemidae), and the gall mites (family Eriophyidae). Among the species that attack animals are members of the sarcoptic mange mites (family Sarcoptidae), which burrow under the skin. Demodex mites (family Demodicidae) are parasites that live in or near the hair follicles of mammals, including humans.
Being unable to fly, mites need some other means of dispersal. On a small scale, walking is used to access other suitable locations in the immediate vicinity. Some species mount to a high point and adopt a dispersal posture and get carried away by the wind, while others waft a thread of silk aloft to balloon to a new position.
Parasitic mites use their hosts to disperse, and spread from host to host by direct contact. Another strategy is phoresy; the mite, often equipped with suitable claspers or suckers, grips onto an insect or other animal, and gets transported to another place. A phoretic mite is just a hitch-hiker and does not feed during the time it is carried by its temporary host. These travelling mites are mostly species that reproduce rapidly and are quick to colonise new habitats.
Mites are tiny, almost invisible, and apart from those that are of economic concern to humans, little studied. The majority are beneficial, living in the soil or aqueous environments and assisting in the decomposition of decaying organic material, or consuming fungi, plant or animal matter, as part of the carbon cycle.
The majority of mite species are harmless to humans and domestic animals, but a few species can colonize mammals directly, acting as vectors for disease transmission, and causing or contributing to allergenic diseases. Mites which colonize human skin are the cause of several types of itchy skin rashes, such as gamasoidosis, rodent mite dermatitis, grain itch, grocer's itch, and scabies; Sarcoptes scabiei is a parasitic mite responsible for scabies which is one of the three most common skin disorders in children. Demodex mites, which are common cause of mange in dogs and other domesticated animals, have also been implicated in the human skin disease rosacea, although the mechanism by which demodex contributes to the disease is unclear.
Chiggers are known primarily for their itchy bite, but they can also spread disease in some limited circumstances, such as scrub typhus. The house-mouse mite is the only known vector of the disease rickettsialpox. House dust mites, found in warm and humid places such as beds, cause several forms of allergic diseases, including hay fever, asthma and eczema, and are known to aggravate atopic dermatitis.
The mite Varroa destructor is a serious pest of honey bees, contributing to colony collapse disorder in commercial hives. The mite is an obligate external parasite, able to reproduce only in bee colonies. It directly weakens its host by sucking up the bee's fat, and can spread RNA viruses including deformed wing virus. Heavy infestation causes the death of a colony, generally over the winter. Since 2006, over 10 million beehives have been lost.
Mites were first observed under the microscope by the English polymath Robert Hooke. In his 1665 book Micrographia, he stated that far from being spontaneously generated from dirt, they were "very prettily shap'd Insects". The world's first science documentary featured cheese mites, seen under the microscope; the short film was shown in London's Alhambra music hall in 1903, causing a boom in the sales of simple microscopes. A few years later, Arthur Conan Doyle wrote a satirical poem, Parable, with the conceit of some cheese mites disputing the origin of the round Cheddar cheese in which they all lived.
Bat-Mite is a fictional character appearing in American comic books published by DC Comics. Bat-Mite is an imp similar to the Superman villain Mister Mxyzptlk. Depicted as a small, childlike man in an ill-fitting costume, Bat-Mite possesses what appear to be near-infinite magical powers, but he actually utilizes highly advanced technology from the fifth dimension that cannot be understood by humans' limited three-dimensional views. Unlike Mxyzptlk, Bat-Mite idolizes his superhero target and thus he has visited Batman on various occasions, often setting up strange events so that he could see his hero in action. Bat-Mite is more of a nuisance than a supervillain, and often departs of his own accord upon realizing that he has angered his idol.Dan the Dyna-Mite
Dan the Dyna-Mite is a fictional character, a teen-aged superhero published by DC Comics. He was the young sidekick to the character TNT, and was created by Mort Weisinger and Hal Sharp in 1942. TNT and Dyna-Mite made their debut in Star Spangled Comics #7 and starred through #23.Demodex
Demodex is a genus of tiny mites that live in or near hair follicles of mammals. Around 65 species of Demodex are known. Two species live on humans: Demodex folliculorum and Demodex brevis, both frequently referred to as eyelash mites. Different species of animals host different species of Demodex. Demodex canis lives on the domestic dog. Infestation with Demodex is common and usually does not cause any symptoms, although occasionally some skin diseases can be caused by the mites. Demodex is derived from Greek δημός dēmos "fat" and δήξ dēx, "woodworm".Demodex mite bite
Demodex mite bite is a cutaneous condition caused by infestation by Demodex folliculorum.Dermanyssus gallinae
Dermanyssus gallinae (also known as the red mite) is an ectoparasite of poultry and has been implicated as a vector of several major pathogenic diseases. Despite its common names, it has a wide range of hosts including several species of wild birds and mammals including humans. In both size and appearance, it resembles the northern fowl mite, Ornithonyssus sylviarum.Good Times
Good Times is an American sitcom that aired for six seasons on CBS from February 8, 1974, to August 1, 1979. Created by Eric Monte and Mike Evans, and developed by Norman Lear, the series' primary executive producer, it was television's first African American two-parent family sitcom. Good Times is a spin-off of Maude, which was itself a spin-off of All in the Family.House dust mite
House dust mites (HDM, or simply dust mites) are a large number of mites found in association with dust in dwellings.The main species are identified as:
Dermatophagoides farinae (American house dust mite)
Dermatophagoides pteronyssinus (European house dust mite)
Euroglyphus maynei (Mayne's house dust mite)M422 Mighty Mite
The M422 'Mighty Mite' is a lightweight ¼-ton 4x4 tactical truck, suitable for airlifting and manhandling. From 1959-1962, the Mighty Mite was built by American Motors for the United States Marine Corps.Mange
Mange is a type of skin disease caused by parasitic mites. Because mites also infect plants, birds, and reptiles, the term "mange", suggesting poor condition of the hairy coat due to the infection, is sometimes reserved only for pathological mite-infestation of nonhuman mammals. Thus, mange includes mite-associated skin disease in domestic animals (cats and dogs), in livestock (such as sheep scab), and in wild animals (for example, coyotes, cougars, and bears). Since mites belong to the arachnid subclass Acari (also called Acarina), another term for mite infestation is acariasis.
Parasitic mites that cause mange in mammals embed themselves in either skin or hair follicles in the animal, depending upon their genus. Sarcoptes spp. burrow into skin, while Demodex spp. live in follicles.
In humans, these two types of mite infections, which would otherwise be known as "mange" in furry mammals, are instead known respectively as scabies and demodicosis.Oribatida
Oribatida (formerly Cryptostigmata), also known as moss mites or beetle mites, are an order of mites, in the "chewing Acariformes" clade Sarcoptiformes. They range in size from 0.2 to 1.4 millimetres (0.008 to 0.055 in).Oribatid mites generally have low metabolic rates, slow development and low fecundity. Species are iteroparous with adults living a relatively long time; for example, estimates of development time from egg to adult vary from several months to two years in temperate forest soils. Oribatid mites have six active instars: prelarva, larva, 3 nymphal instars and the adult. All these stages after the prelarva feed on a wide variety of material including living and dead plant and fungal material, lichens and carrion; some are predatory, but none is parasitic and feeding habits may differ between immatures and adults of the same species. Many species have a mineralized exoskeleton.The Oribatida are of economic importance as hosts of various tapeworm species, and by increasing the breakdown of organic material in the soil, in a similar manner to earthworms.Prostigmata
The Prostigmata is a suborder of mites belonging to the order Trombidiformes, which contains the "sucking" members of the "true mites" (Acariformes).
Many species are notorious pests on plants. Well-known examples of prostigmatan plant parasites are species of the gall mites (Eriophyidae, e.g. the redberry mite Acalitus essigi), Tarsonemidae (e.g. the cyclamen mite, Steneotarsonemus pallidus), and the spider mites of the Tetranychidae (e.g. the two-spotted spider mite, Tetranychus urticae).
Other Prostigmata live as parasites on vertebrates (e.g. Demodex mites of the Demodecidae) or invertebrates (e.g. Polydiscia deuterosminthurus of the Tanaupodidae or the honeybee tracheal mite, Acarapis woodi, of the Tarsonemidae). There are also some forms (e.g. Smarididae) that are predators of small invertebrates – including smaller Prostigmata – yet others have a more varied lifestyle (e.g. Tydeidae) or switch their food sources as they mature (e.g. Erythraeidae). The suborder also include the family Halacaridae (marine mites).Some of the Prostigmata parasitizing vertebrates are of medical relevance due to causing skin diseases in humans. These include for example harvest mites ("chiggers") of the Trombiculidae.Rickettsia akari
Rickettsia akari is a species of Rickettsia which causes rickettsialpox.After a 1946 outbreak of a rickettsial-type disease at an apartment complex in Kew Gardens, Queens, an investigation was performed to identify the source of the infections. The incinerators in the buildings were not operated on a daily basis, leading to a buildup in food waste and attracting mice that were rampant throughout the building. The Mus musculus mice were found to be carrying mites, identified as the house mouse mite, Allodermanyssus sanguineus. Self-trained entomologist Charles Pomerantz asked permission to search the site and found the mites at various sites throughout the building, with blood-engorged mites found near chutes leading to the incinerator. The mites were collected and brought to a laboratory of the United States Public Health Service, which found in the mites an organism that had also been isolated from the mice, and from the blood of individuals infected with the disease.The organism was given its name by physician Robert Huebner, one of the scientists who had tracked down the source of the original 1946 epidemic; the akari portion of the bacteria's name represents the Greek word for "mite".
While active efforts to exterminate mice from buildings has greatly reduced recurrences of the diseases, a July 2002 report from the Centers for Disease Control and Prevention report a recent case in North Carolina, noting that cases have been reported in Croatia and Ukraine and that the R. akari organism may exist in "sylvan cycles", such as its isolation from voles in Korea.Sarcoptes scabiei
Sarcoptes scabiei or the itch mite is a parasitic mite (an arthropod) that burrows into skin and causes scabies. The mite is found in all parts of the world. Humans are not the only mammals that can become infected. Other mammals, such as wild and domesticated dogs and cats (in which it is one cause of mange) as well as ungulates, wild boars, bovids, wombats, koalas, and great apes are affected.
The Italian biologists Giovanni Cosimo Bonomo and Diacinto Cestoni showed in the 17th century that scabies is caused by Sarcoptes scabiei; this discovery of the itch mite in 1687 marked scabies as the first disease of humans with a known microscopic causative agent. The disease produces intense, itchy skin rashes when the impregnated female tunnels into the stratum corneum of the skin and deposits eggs in the burrow. The larvae, which hatch in three to 10 days, move about on the skin, moult into a nymphal stage, and then mature into adult mites. The adult mites live three to four weeks in the host's skin.Scabies
Scabies, also known as the seven-year itch, is a contagious skin infestation by the mite Sarcoptes scabiei. The most common symptoms are severe itchiness and a pimple-like rash. Occasionally, tiny burrows may be seen in the skin. In a first-ever infection a person will usually develop symptoms in between two and six weeks. During a second infection symptoms may begin in as little as 24 hours. These symptoms can be present across most of the body or just certain areas such as the wrists, between fingers, or along the waistline. The head may be affected, but this is typically only in young children. The itch is often worse at night. Scratching may cause skin breakdown and an additional bacterial infection of the skin.Scabies is caused by infection with the female mite Sarcoptes scabiei var. hominis, an ectoparasite. The mites burrow into the skin to live and deposit eggs. The symptoms of scabies are due to an allergic reaction to the mites. Often, only between 10 and 15 mites are involved in an infection. Scabies is most often spread during a relatively long period of direct skin contact with an infected person (at least 10 minutes) such as that which may occur during sex or living together. Spread of disease may occur even if the person has not developed symptoms yet. Crowded living conditions, such as those found in child-care facilities, group homes, and prisons, increase the risk of spread. Areas with a lack of access to water also have higher rates of disease. Crusted scabies is a more severe form of the disease. It typically only occurs in those with a poor immune system and people may have millions of mites, making them much more contagious. In these cases, spread of infection may occur during brief contact or by contaminated objects. The mite is very small and usually not directly visible. Diagnosis is based on the signs and symptoms.A number of medications are available to treat those infected, including permethrin, crotamiton, and lindane creams and ivermectin pills. Sexual contacts within the last month and people who live in the same house should also be treated at the same time. Bedding and clothing used in the last three days should be washed in hot water and dried in a hot dryer. As the mite does not live for more than three days away from human skin, more washing is not needed. Symptoms may continue for two to four weeks following treatment. If after this time symptoms continue, retreatment may be needed.Scabies is one of the three most common skin disorders in children, along with ringworm and bacterial skin infections. As of 2015, it affects about 204 million people (2.8% of the world population). It is equally common in both sexes. The young and the old are more commonly affected. It also occurs more commonly in the developing world and tropical climates. The word scabies is from Latin: scabere, "to scratch". Other animals do not spread human scabies. Infection in other animals is typically caused by slightly different but related mites and is known as sarcoptic mange.Spider mite
Spider mites are members of the Acari (mite) family Tetranychidae, which includes about 1,200 species. They generally live on the undersides of leaves of plants, where they may spin protective silk webs, and they can cause damage by puncturing the plant cells to feed. Spider mites are known to feed on several hundred species of plants.TNT (comics)
TNT is a DC Comics superhero from the 1940s. TNT and his side-kick Dan the Dyna-Mite were created by Mort Weisinger for DC Comics, and made their debut in Star-Spangled Comics #7 (April 1942)
The "human hand grenades" had a short lived career during the Golden Age of Comic Books, reappearing occasionally in reprint form during the seventies, returning in Super Friends # 12, and appearing from time to time in All-Star Squadron and its Post-Crisis sequel, Young All-Stars.Tetranychus urticae
Tetranychus urticae (common names include red spider mite and two-spotted spider mite) is a species of plant-feeding mite generally considered to be a pest. It is the most widely known member of the family Tetranychidae or spider mites. Its genome was fully sequenced in 2011, and was the first genome sequence from any chelicerate.Trombiculidae
Trombiculidae (; also called berry bugs, harvest mites, red bugs, scrub-itch mites and aoutas) are a family of mites. The best known of the Trombiculidae are the chiggers. The two widely recognized definitions of "chigger" are the scientific (or taxonomic) and the common, the latter of which can be found in English and medical dictionaries. According to most dictionaries, the several species of Trombiculidae that bite their host in their larval stage and cause "intense irritation" or "a wheal, usually with severe itching and dermatitis", are called chiggers. The scientific definition seemingly includes many more, but not all species of Trombiculidae.
Trombiculidae live in forests and grasslands and are also found in the vegetation of low, damp areas such as woodlands, berry bushes, orchards, along lakes and streams, and even in drier places where vegetation is low, such as lawns, golf courses, and parks. They are most numerous in early summer when grass, weeds, and other vegetation are heaviest. In their larval stage, they attach to various animals, including humans, and feed on skin, often causing itching. These relatives of ticks are nearly microscopic, measuring 0.4 mm (1/60 of an inch) and have a chrome-orange hue. There is a marked constriction in the front part of the body in the nymph and adult stages. The best known species of chigger in North America is the hard-biting Trombicula alfreddugesi of the southeastern United States, humid Midwest and Mexico; in the UK, the most prevalent chigger, called the "harvest mite", is Trombicula autumnalis, with distribution through Western Europe to Eastern Asia.Trombiculid mites go through a lifecycle of egg, larva, nymph, and adult. The larval mites feed on the skin cells of animals. The six-legged parasitic larva feeds on a large variety of creatures, including humans, rabbits, toads, box turtles, quail, and even some insects. After crawling onto their hosts, they inject digestive enzymes into the skin that break down skin cells. They do not actually "bite", but instead form a hole in the skin called a stylostome and chew up tiny parts of the inner skin, thus causing severe irritation and swelling. The severe itching is accompanied by red, pimple-like bumps (papules) or hives and skin rash or lesions on a sun-exposed area. For humans, itching usually occurs after the larvae detach from the skin.After feeding on their hosts, the larvae drop to the ground and become nymphs, then mature into adults which have eight legs and are harmless to humans. In the postlarval stage, they are not parasitic and feed on plant material. The females lay three to eight eggs in a clutch, usually on a leaf or under the roots of a plant, and die by autumn.Varroa destructor
Varroa destructor (Varroa mite) is an external parasitic mite that attacks the honey bees Apis cerana and Apis mellifera. The disease caused by the mites is called varroosis.
The Varroa mite can only reproduce in a honey bee colony. It attaches to the body of the bee and weakens the bee by sucking fat bodies . In this process, RNA viruses such as the deformed wing virus (DWV) spread to bees. A significant mite infestation will lead to the death of a honey bee colony, usually in the late autumn through early spring. The Varroa mite is the parasite with possibly the most pronounced economic impact on the beekeeping industry. Varroa is considered to be one of multiple stress factors contributing to the higher levels of bee losses around the world.
Extant Arthropoda classes by subphylum