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A microscopic mite Lorryia formosa.

Mites, along with ticks, belong to the subclass Acarina (also known as Acari) and the class Arachnida. 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 are microscopic) go largely unnoticed. Many live freely in the soil or water, but there are also a large number of species that live as parasites on plants, animals, and some that feed on mold.

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).

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 honey bees. 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.

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.

The scientific discipline devoted to the study of ticks and mites is called acarology.

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 & Koerner 2007).

Contents

Systematics

In the usual taxonomy, the ticks form one of several superfamilies in the taxon comprising the mites. For the systematics of mites, see Acarina.

Allergy

Mites cause several forms of allergic diseases, including hay fever, asthma and eczema and are known to aggravate atopic dermatitis.[1] Mites are usually found in warm and humid locations, including beds. It is thought that inhalation of mites during sleep exposes the human body to some antigens which eventually induce hypersensitivity reaction.[2] Dust mite allergens are thought to be among the heaviest dust allergens.[3]

Like most of the other types of allergy, treatment of mite allergy starts with avoidance. There is a strong body of evidence showing that avoidance should be helpful in patients with atopic dermatitis triggered by exposure to mites.[4] Regular washing of mattresses and blankets with hot water can help in this regard.[5] Antihistamines are also useful; Cetirizine, for example, is shown to reduce allergic symptoms of patients.[6] However not all types of mites are infectious including the Alaskozetes antarcticus an arctic inhabiting mite.[7]

See also

References

  1. ^ Klenerman, Paul; Lipworth, Brian; authors. "House dust mite allergy". NetDoctor. http://www.netdoctor.co.uk/health_advice/facts/allergyhousedustmite.htm. Retrieved 2008-02-20.  
  2. ^ "Hypersensitivity reaction to mite allergens". Allergy Guide. http://www.alergy.org.uk/mite-alergy.html. Retrieved 2008-02-20.  
  3. ^ "Dust allergens". AllergyEscape.com. http://www.allergyescape.com/dust-mites.html. Retrieved 2008-02-20.  
  4. ^ "Consultation and referral guidelines citing the evidence: how the allergist–immunologist can help.". National Guideline Clearinghouse. February 2006. http://www.guidelines.gov/summary/summary.aspx?doc_id=9334&nbr=005003. Retrieved 2008-02-20.  
  5. ^ "Rhinitis management.". National Guideline Clearinghouse. May 2003. http://www.guidelines.gov/summary/summary.aspx?doc_id=3875&nbr=003084. Retrieved 2008-02-20.  
  6. ^ Ciprandi G, Tosca M, Passalacqua G, Canonica GW (September 2001). "Long-term cetirizine treatment reduces allergic symptoms and drug prescriptions in children with mite allergy". Ann Allergy Asthma Immunol 87 (2): 222–6. PMID 11570619.  
  7. ^ "Consultation and referral guidelines citing the evidence: how the allergist–immunologist can help.". National Guideline Clearinghouse. February 2006. http://www.guidelines.gov/summary/summary.aspx?doc_id=9334&nbr=005003. Retrieved 2008-02-20.  
  • 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


1911 encyclopedia

Up to date as of January 14, 2010

From LoveToKnow 1911

MITE, a name applied to an order of small Arachnida, with which this article deals, and to a coin of very slight value. The origin of both would appear to be ultimately the same, viz. a root mei-, implying something exceedingly small. It has been suggested that the name for the animal comes from a secondary root of the root mei-, to cut, whence come such words as Goth. maitan, to cut, and Ger. messer, knife. In this case mite would mean "the biter" or "cutter." The coin was originally a Flemish copper coin (Dutch mijt) worth one-third or, according to some authorities, a smaller fraction of the Flemish penning, penny. It has become a common expression in English for a coin of the smallest value, from its use to translate Gr. XE7rT611, two of which make a KoOpavrns, translated "farthing" (Mark xii. 43).

In zoology, "mite" is the common name for minute members of the class Arachnida (q.v.), which, with the ticks, constitute the order Acari. The word "mite," however, is merely a popular and convenient term for certain groups of Acari, and does not connote a natural assemblage as contrasted with the ticks (q.v.). Mites are either free-living or parasitic throughout their lives or parasitic at certain periods and free-living at others. They are almost universally distributed, and are found wherever terrestrial vegetation, even of the lowliest kind, occurs. They are spread from the arctic to the antarctic hemisphere, and inhabit alike the land, fresh-water streams and ponds, brackish marshes and the sea. The largest species, which occur in the tropics, reach barely half an inch in length; while the smallest, the most diminutive of the Arthropoda, are invisible to the naked eye.

Mites are divided into a considerable number of families. The Bdellidae (Bdella) are free-living forms with long antenniform palpi. The large tropical forms above mentioned belong to the genus Trombidium of the family Trombidiidae. The members of this genus are covered with velvety plush-like hairs, often of an exquisite crimson colour. The legs are adapted for crawling or running, and the palpi are raptorial. They are non-parasitic in the adult stage; but immature individuals of a British species (T. holosericeum) are parasitic upon various animals (see Harvest BuG). The Tetranychidae are nearly related to the last. A well-known example, Tetranychus telarius, spins webs on the backs of leaves, and is sometimes called the money spider. The fresh-water mites or Hydrachnidae are generally beautifully coloured red or green, and are commonly globular in shape. Their legs are furnished with Iong hairs for swimming. The marine mites of the family Halacaridae, on the contrary, are not active swimmers but merely creep on the stems of seaweeds and zoophytes. The Gamasidae are mostly free-living forms with a thick exoskeleton, and are allied to the Ixodidae or ticks (q.v.). A common species is Gamasus coleoptratorum, the females and young of which may be found upon the common dung-beetle. The Oribatidae or beetle-mites, so called from their resemblance to minute beetles, are non-parasitic, and often go through remarkable metamorphoses during development. The Sarcoptidae, as stated below, are mostly parasitic forms. Some members of this family, however, live in decaying animal substances, the best known perhaps being the cheese-mite (Tyroglyphus Biro) which infests cheese, especially Stilton, in thousands. An allied species (T. entomophagus) often causes great damage to collections of insects by destroying the dried specimens. They may be easily exterminated by application of benzine, which does not harm the contents of the cabinet.

From the economic standpoint the most important mites are those which are parasitic upon mammals and birds. They belong to the four families, Gamasidae, Trombidiidae, Sarcoptidae and Demodicidae. Most of the Gamasidae are free-living mites. The family, however, contains an aberrant genus, Dermanyssus, of which several species have been described, although they are all perhaps merely varieties of one and the same species commonly known as D. gallinae or D. avium. This species is found in fowlhouses, dovecotes and bird-cages. During the day they lurk in cracks in the floor, walls or perches, and emerge at night to attack the roosting birds. They are a great pest, and frequently do much damage to birds both by sucking their blood and by depriving them of rest at night. They are sometimes transferred from birds to mammals. The Trombidiidae also are mostly free-living predaceous mites. A few, however, are parasitic upon mammals and birds, the best-known being Trombidium holosericeum, the larva of which attacks human beings, as well as chickens and other birds, sometimes producing considerable mortality amongst them (see Harvest Bug). Another genus, Cheyletiella, affects rabbits as well as birds. Birds are also attacked by many species of Sarcoptidae, which according to the organs infected are termed plumicolae (Analgesinae), epidermicolae (Epidermoptinae), and cysticolae (Cytoditinae). The Analgesinae (Pterolichus, Analges) live almost wholly upon and between the barbules of the feathers. They are found in nearly every species of bird without apparently affecting the health in any way. The Epidermoptinae (Epidermoptes) occur on diseased fowls and live, as their name indicates, upon the skin at the base of the feathers, where their presence gives rise to an accumulation of yellowish scales. The Cytoditinae (Cytodites), on the other hand, live in the subcutaneous or intermuscular connective tissue round the respiratory organs, or in the air sacs, especially of gallinaceous species. They also penetrate to certain internal organs, and may become encysted and give rise to tubercle-like nodules. Sometimes they exist in such quantities in the air passages as to cause coughing and asphyxia.

The cutaneous mites, mentioned above, and others akin to them, produce no very marked disturbance in the skin of the species they infest. They merely suck the blood or feed upon the feathers, scurf and desquamating epidermis. Hence they are termed "non-psoric" mites. A certain number of species, however, called in contradistinction "psoric" mites, give rise by their bites, by the rapidity of their multiplication, and by the excavation of galleries in the skin, to a highly contagious disease known as scabies or mange, which if not treated in time produces the gravest results. These mites belong exclusively to the Sarcoptidae and Demodicidae. A variety of species are responsible for Sarcoptic mange, Sarcoptes mutans producing it in the feet of gallinaceous and passerine birds by burrowing beneath the scales and giving rise to a crusted exudation which pushes up beneath and between the scales. Feather scabies or depluming scabies of poultry is caused by another species, laevis. Three genera of Sarcoptidae, namely Sarcoptes Chorioptes and Psoroptes cause mange or scabies in mammals, the mange produced by Sarcoptes being the most serious form of the disease, because the females of the species which produces it, Sarcoptes scabiei, burrow beneath the skin and are more difficult to reach with acaricides. A considerable number of varieties of this species have been named after the hosts upon which they most commonly and typically occur, such as scabiei hominis, equi, bovis, caprae, ovis, cameli, lupi, vulpis, &c.; but they are not restricted to the mammals from which their names have been derived and structural differences between them are often difficult to define and sometimes non-existant. Under favourable conditions the multiplication of this species is very rapid. It has been computed indeed that a single pair may give rise to one million and a half individuals in about three months. Psoroptes lives in the epidermic incrustations to which it gives rise, without, however, excavating subcutaneous burrows. One species, communis, is known to affect various domestic animals. Of the genus Chorioptes two species have been described on domestic animals, viz. Ch. symbiotes, which has the same mode of life as Psoroptes communis and Ch. cynotis, which has been detected only in the ears of certain carnivora such as dogs, cats and ferrets. Mange, if taken in time, can be cured by applications of sulphur ointment or of sulphur mixed with an animal or vegetable oil. Mites of the family Demodicidae give rise to a skin disease called "Demodecic or follicular mange," which is often serious and always difficult to cure on account of the deep situation taken up by the parasites. These infest the hair follicles and sebaceous glands, and are therefore termed Demodex folliculorunt. These mites differ greatly from those previously noticed - in the reduction of their legs to short threejointed tubercles, and in the great elongation of the abdomen to form an annulated flexible postanal area to the body. They live not uncommonly in small numbers in the skin of the human face and their presence may never be detected. They also occur on dogs, pigs and other domesticated animals, as well as on mice and bats, and numerous varieties named after their hosts, hominis, bovis, canis, cati, &c., have been described, but they apparently differ from each other, principally in size.

The mites of the family Eriophyidae or Phytoptidae produce in various plants pathological results analogous to those produced in animals by parasitical Sarcoptidae and by Demodicidae. As in the Demodicidae the abdomen is elongate and annulate, but the Eriophyidae differ from all other mites in having permanently lost the last two pairs of legs. The excrescences and patches they produce on leaves are called "galls," the best known of which are perhaps the nail-galls of the lime caused by Eriophyes tiliae. A very large number of species have been described and named after the plants upon which they live. They often inflict very considerable loss upon fruit-growers by destroying the growing buds of the trees. (R. I. P.)


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Up to date as of January 23, 2010

From BibleWiki


contraction of minute, from the Latin minutum, the translation of the Greek word lepton, the very smallest bronze of copper coin (Luke 12:59; 21:2). Two mites made one quadrans, i.e., the fourth part of a Roman as, which was in value nearly a halfpenny. (See FARTHING.)

This entry includes text from Easton's Bible Dictionary, 1897.

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