Difference between revisions of "Mite" - New World Encyclopedia
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| − | ''' | + | [[Image:Peacock mite, Tuckerella sp.jpg|thumb|right|240px|Peacock mite]] |
| + | '''Mite''' is the common name for various minute (often [[microscope|microscopic]]) [[arachnid]]s (class Arachnida) in the subclass '''Acarina''' (or '''Acari'''), a taxon of [[arthropod]]s (phylum Arthropoda) that contains [[tick]]s as well. While arachnids are characterized by four pairs of segmented walking legs and a body divided into two regions, the cephalothorax and the abdomen, mites are typically characterized by an unsegmented body (as with the ticks), and sometimes by only one or three pairs of legs in the adult stage, and with larval and prelarval stages with a maximum of three pairs of legs. Mites are typically characterized by very small size relative to the generally larger ticks, although the red velvet mites can reach larger sizes. | ||
| + | Mites are among the most diverse and successful of all the [[invertebrate]] groups. They have exploited an incredible array of [[habitat (ecology)|habitat]]s, and because of their small size most go totally unnoticed. Many live freely in the soil or water, but there are also a large number of species that live as [[parasite]]s on plants or animals and even some that feed on [[mold mites|mold]]. | ||
| − | + | It is estimated that over 50,000 species have been described (as of 1999) and that a million or more species are currently living. | |
| − | + | The scientific discipline devoted to the study of ticks and mites is called [[acarology]]. | |
| − | + | The study of mites and ticks is called '''acarology''' (from the [[Greek language|Greek]]: ἀκάρι, ''akari'', a type of mite; and λόγος, ''logos'', "knowledge")<ref name="Walter">{{cite book |author=D. E. Walter & H. C. Proctor |year=1999 |title=Mites: Ecology, Evolution and Behaviour |publisher=University of NSW Press, Sydney and [[CAB International|CABI]], Wallingford |id=ISBN 0-86840-529-9}}</ref>, and the leading [[scientific journal]]s for acarology include ''[[Acarologia]]'', ''[[Experimental and Applied Acarology]]'' and ''[[International Journal of Acarology]]''. | |
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| + | ==Description== | ||
| + | The [[arthropod]] class Arachnida, to which mites belong, is a largely terrestrial group that also includes [[spider]]s, [[tick]]s, [[scorpion]]s, and [[opiliones|harvestmen]] (daddy longlegs). Arachnids are characterized by the possession of a two-segmented body, a pair of jointed appendages on each segment, and an [[exoskeleton]]. The two-segmented body is made up of a [[cephalothorax]] and an [[abdomen]], the cephalothorax being derived from the fusion of the [[cephalon]] (head) and the [[thorax]]. Arachnids belong to the subphylum Chelicerata, a group that receives its name from pointed appendages that grasp the food in place of the chewing mandibles most other arthropods have. The chelicerae serve to macerate food particles. | ||
| + | Members of Arachnida may be easily distinguished from [[insect]]s (class Insecta) by the fact that arachnids have no antennae and no wings and arachnids have eight [[arthropod leg|legs]] whereas insects have six. | ||
| + | Mites and ticks belong to the arachnid taxon Acarina or Acari. Most acarines are minute to small (e.g. 0.08–1.0 millimeters (mm), but the largest Acari (some ticks and red velvet mites) may reach lengths of 10–20 mm. The [[life cycle]] of mites includes four stages: egg, larva, nymph, and adult. While arachnids largely are terrestrial, some mites can be found in aquatic (freshwater and marine) environments. | ||
| − | + | As members of [[Arachnida]], mites should have a segmented body with the segments organized into two [[tagma]]ta: a [[prosoma]] (cephalothorax) and an [[opisthosoma]] (abdomen). However, only the faintest traces of primary segmentation remain in mites, the prosoma and opisthosoma are insensibly fused, and a region of flexible cuticle (the cirumcapitular furrow) separates the chelicerae and pedipalps from the rest of the body. This anterior body region is called the capitulum or gnathosoma and is also found in the [[Ricinulei]]. The remainder of the body is called the idiosoma and is unique to mites. | |
| + | Most adult mites have four pairs of legs, like other arachnids. However, the [[larva]]l and prelarval stages of mites have a maximum of three pairs of legs; the fourth pair appears when they [[ecdysis|molt]] into [[nymph (biology)|nymph]]s. Some adult mites also have fewer than four pairs of legs. For example, gall mites like ''Phyllocoptes variabilis'' (superfamily Eriophyioidea) have a wormlike body with only two pairs of legs; some parasitic mites have only one or three pairs of legs in the adult stage. Adult mites with only three pairs of legs may be called 'larviform'. | ||
| + | ==Habitat and behavior== | ||
| + | Mites may be free-living or parasitic, living on plants, animals, in the soil, and so forth. They feed on plant and animals, as well as detritus and humus (organic material in [[soil]]). Many are parasitic and may spread disease. Some of the plant pests include the so called [[spider mite]]s (family [[Tetranychidae]]), [[thread-footed mite]]s (family [[Tarsonemidae]]), and the [[gall mite]]s (family [[Eriophyidae]]). Among the species that attack animals are members of the [[Mange#Sarcoptic Mange|Sarcoptic Mange]] mites (family [[Sarcoptidae]]), which burrow under the skin. [[Demodex mite]]s (family [[Demodicidae]]) are parasites that live in or near the [[hair follicle]]s of [[mammal]]s, including humans. Perhaps the best-known mite, though, is the [[house dust mite]] (family [[Pyroglyphidae]]). | ||
| + | Chiggers, the larval stage of harvest mites ([[genus]] Trombicula), can carry ''Rickettsia tsutsugamushi'' (''Orientia tsutsugamushi''), the bacteria that causes [[typhus|scrub typhus]]. | ||
| + | Insects may also have parasitic mites. Examples are ''[[Varroa destructor]]'' which attaches to the body of the [[honeybee]], and ''[[Acarapis woodi]]'' (family [[Tarsonemidae]]), which lives in the [[invertebrate trachea|trachea]]e of honeybees. There are hundreds of species of mites associated with other bee species, and most are poorly described and understood. Some are thought to be parasites, while others beneficial [[symbiosis|symbionts]]. | ||
| + | The tropical species ''[[Archegozetes longisetosus]]'' is one of the strongest animals in the world, relative to its mass (100 μg): It lifts up to 1182 times its own weight, over five times more than would be expected of such a minute animal (Heethoff and Koerner 2007). | ||
| + | ==Systematics== | ||
| + | [[Image:Rust Mite, Aceria anthocoptes.jpg|right|200px|thumb|Rust mite (size: 30 [[micrometre]]s)]] | ||
| + | There are over 45,000 described species of mites [http://www.sa.waterwatch.org.au/pdfs/critters_4_mites.pdf]. Scientists believe that we have only found 5% of the total diversity of mites. Mites are believed to have existed for around 400 million years. | ||
| − | + | are a [[taxon]] of [[arachnids]] that contains [[mite]]s and [[tick]]s. The diversity of the Acari is extraordinary and its fossil history goes back to the [[Devonian]] era. As a result, acarologists (the people who study mites and ticks) have proposed a complex set of taxonomic ranks to classify mites. In most modern treatments, the Acari is considered a [[subclass]] of [[Arachnid]]a and is composed of 2-3 orders or superorders: [[Acariformes]], [[Parasitiformes]], and Opilioacariformes. The latter is often considered a subgroup within the Parasitiformes. The monophyly of the Acari is open to debate and the relationships of the acarine orders to other arachnids is not at all clear. | |
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The [[phylogeny]] of the Acari is still disputed and several taxonomic schemes have been proposed for its classification. Most workers agree that the Acari contains two separate lineages: the Acariformes (also Actinotrichida) and the Parasitiformes (also Anactinotrichida). However, some workers treat these groups as superorders and others as orders. | The [[phylogeny]] of the Acari is still disputed and several taxonomic schemes have been proposed for its classification. Most workers agree that the Acari contains two separate lineages: the Acariformes (also Actinotrichida) and the Parasitiformes (also Anactinotrichida). However, some workers treat these groups as superorders and others as orders. | ||
Revision as of 02:46, 17 October 2007
Mite is the common name for various minute (often microscopic) arachnids (class Arachnida) in the subclass Acarina (or Acari), a taxon of arthropods (phylum Arthropoda) that contains ticks as well. While arachnids are characterized by four pairs of segmented walking legs and a body divided into two regions, the cephalothorax and the abdomen, mites are typically characterized by an unsegmented body (as with the ticks), and sometimes by only one or three pairs of legs in the adult stage, and with larval and prelarval stages with a maximum of three pairs of legs. Mites are typically characterized by very small size relative to the generally larger ticks, although the red velvet mites can reach larger sizes.
Mites are among the most diverse and successful of all the invertebrate groups. They have exploited an incredible array of habitats, and because of their small size most go totally unnoticed. Many live freely in the soil or water, but there are also a large number of species that live as parasites on plants or animals and even some that feed on mold.
It is estimated that over 50,000 species have been described (as of 1999) and that a million or more species are currently living.
The scientific discipline devoted to the study of ticks and mites is called acarology.
The study of mites and ticks is called acarology (from the Greek: ἀκάρι, akari, a type of mite; and λόγος, logos, "knowledge")[1], and the leading scientific journals for acarology include Acarologia, Experimental and Applied Acarology and International Journal of Acarology.
Description
The arthropod class Arachnida, to which mites belong, is a largely terrestrial group that also includes spiders, ticks, scorpions, and harvestmen (daddy longlegs). Arachnids are characterized by the possession of a two-segmented body, a pair of jointed appendages on each segment, and an exoskeleton. The two-segmented body is made up of a cephalothorax and an abdomen, the cephalothorax being derived from the fusion of the cephalon (head) and the thorax. Arachnids belong to the subphylum Chelicerata, a group that receives its name from pointed appendages that grasp the food in place of the chewing mandibles most other arthropods have. The chelicerae serve to macerate food particles.
Members of Arachnida may be easily distinguished from insects (class Insecta) by the fact that arachnids have no antennae and no wings and arachnids have eight legs whereas insects have six.
Mites and ticks belong to the arachnid taxon Acarina or Acari. Most acarines are minute to small (e.g. 0.08–1.0 millimeters (mm), but the largest Acari (some ticks and red velvet mites) may reach lengths of 10–20 mm. The life cycle of mites includes four stages: egg, larva, nymph, and adult. While arachnids largely are terrestrial, some mites can be found in aquatic (freshwater and marine) environments.
As members of Arachnida, mites should have a segmented body with the segments organized into two tagmata: a prosoma (cephalothorax) and an opisthosoma (abdomen). However, only the faintest traces of primary segmentation remain in mites, the prosoma and opisthosoma are insensibly fused, and a region of flexible cuticle (the cirumcapitular furrow) separates the chelicerae and pedipalps from the rest of the body. This anterior body region is called the capitulum or gnathosoma and is also found in the Ricinulei. The remainder of the body is called the idiosoma and is unique to mites.
Most adult mites have four pairs of legs, like other arachnids. However, the larval and prelarval stages of mites have a maximum of three pairs of legs; the fourth pair appears when they molt into nymphs. Some adult mites also have fewer than four pairs of legs. For example, gall mites like Phyllocoptes variabilis (superfamily Eriophyioidea) have a wormlike body with only two pairs of legs; some parasitic mites have only one or three pairs of legs in the adult stage. Adult mites with only three pairs of legs may be called 'larviform'.
Habitat and behavior
Mites may be free-living or parasitic, living on plants, animals, in the soil, and so forth. They feed on plant and animals, as well as detritus and humus (organic material in soil). Many are parasitic and may spread disease. Some of the 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. Perhaps the best-known mite, though, is the house dust mite (family Pyroglyphidae).
Chiggers, the larval stage of harvest mites (genus Trombicula), can carry Rickettsia tsutsugamushi (Orientia tsutsugamushi), the bacteria that causes scrub typhus.
Insects may also have parasitic mites. Examples are Varroa destructor which attaches to the body of the honeybee, and Acarapis woodi (family Tarsonemidae), which lives in the tracheae of honeybees. There are hundreds of species of mites associated with other bee species, and most are poorly described and understood. Some are thought to be parasites, while others beneficial symbionts.
The tropical species Archegozetes longisetosus is one of the strongest animals in the world, relative to its mass (100 μg): It lifts up to 1182 times its own weight, over five times more than would be expected of such a minute animal (Heethoff and Koerner 2007).
Systematics
There are over 45,000 described species of mites [1]. Scientists believe that we have only found 5% of the total diversity of mites. Mites are believed to have existed for around 400 million years.
are a taxon of arachnids that contains mites and ticks. The diversity of the Acari is extraordinary and its fossil history goes back to the Devonian era. As a result, acarologists (the people who study mites and ticks) have proposed a complex set of taxonomic ranks to classify mites. In most modern treatments, the Acari is considered a subclass of Arachnida and is composed of 2-3 orders or superorders: Acariformes, Parasitiformes, and Opilioacariformes. The latter is often considered a subgroup within the Parasitiformes. The monophyly of the Acari is open to debate and the relationships of the acarine orders to other arachnids is not at all clear.
The phylogeny of the Acari is still disputed and several taxonomic schemes have been proposed for its classification. Most workers agree that the Acari contains two separate lineages: the Acariformes (also Actinotrichida) and the Parasitiformes (also Anactinotrichida). However, some workers treat these groups as superorders and others as orders.
- Acariformes is the most diverse order/superorder of mites.
- Order/Suborder:
- Trombidiformes - plant parasitic mites (spider mites, peacock mites, gall mites, red-legged earth mites, etc.), snout mites, chiggers, hair follicle mites, velvet mites, water mites, etc.
- Sarcoptiformes - oribatid, endeostigmatan, and astigmatan mites
- Endeostigmata - basal sarcoptiform lineages
- Oribatida - oribatid mites, beetle mites, armored mites (also cryptostigmata)
- Astigmata - stored product, fur, feather, dust, and human itch mites, etc.
- Parasitiformes is the order/superorder that contains the ticks and a variety of mites.
- Order/Suborder:
- Mesostigmata - bird mites, phytoseiid mites, raubmilben
- Ixodida - hard and soft ticks
- Holothyrida - holothyrans
- Opilioacariformes is a small order or suborder of parasitiform mites that are superficially similar to harvestmen (opiliones, hence their name).
- Obsolete names:
- Opilioacarida
- Notostigmata
See also
- Harvest mite (chigger)
- Mold mites
- House dust mite
- Miticide
- Diseases of the honey bee
- Anti-itch drug
- Category:Antiparasitic_agents
ReferencesISBN links support NWE through referral fees
- Heethoff, M. & Koerner, L. (2007): Small but powerful - The oribatid mite Archegozetes longisetosus Aoki (Acari, Oribatida) produces disproportionate high forces. J. Exp. Biol. 210(17): 3036-3042. DOI:10.1242/jeb.008276 (Abstract)
External links
- PARASITIC MITES OF HUMANS University of Kentucky
- Red velvet mite - Trombidium sp. diagnostic photographs
- Worldwide honey bee decline due to mite infestations - article, photographs
- Control of the citrus rust mite hosted by the UNT Government Documents Department
Rust mite
Aceria anthocoptes
Flat mite
Brevipalpus phoenicis
House dust mite
Dermatophagoides pteronyssinus- Yellow mite (Tydeidae), Lorryia formosa.jpg
Yellow mite
Lorryia formosa 
Yellow mite
Lorryia formosa
Plant mites forming a reproductive colony
Velvet mite
_Lorryia_formosa_2_edit.jpg)
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- ↑ D. E. Walter & H. C. Proctor (1999). Mites: Ecology, Evolution and Behaviour. University of NSW Press, Sydney and CABI, Wallingford. ISBN 0-86840-529-9.
