Mesostigmata is an order of mites belonging to the Parasitiformes. They are by far the largest group of Parasitiformes, with over 8,000 species in 130 families. Mesostigmata includes parasitic as well as free-living and predatory forms. They can be recognized by the single pair of spiracles positioned laterally on the body.
Amongst the best known species are Varroa destructor, an economically important parasite of honey bees, as well as the red mite (Dermanyssus gallinae), a parasite of poultry, most commonly chickens.
Description
Mesostigmata are mites ranging from 0.12–4mm long (0.2–4mm according to another source[2]). They have a pair of stigmatal openings above legs III-IV usually associated with a peritrematal groove. The gnathosoma has a sclerotised ring around the bases of the chelicerae (basis capitulum). The palps have 5 (rarely 4) free segments and usually a subdistal palp apotele. The chelicerae are 3-segmented. The subcapitulum usually has a median groove with transverse rows of 1-many denticles. There are usually bifurcate or membranous corniculi present. Except in some parasitic species, a flagellate tritosternum is present. The coxae of the legs are freely articulating with the body. The intercoxal region has sternal and genital shield elements. Adults have a genital opening and either chelicerae modified for sperm transfer (if male) or a sperm-receiving structure (if female).[3]
The above description applies to adults. Larvae have six legs, instead of the eight possessed by later stages, and may or may not feed. There are two nymphal stages (protonymph, deutonymph) that usually have lightly sclerotized dorsal, intercoxal and ventral plates.[3]
Ecology
Many Mesostigmata are free-living predators of invertebrates that live in soil and litter, on the soil surface or on plants.[4] There are also some that live in freshwater.[5] Other Mesostigmata are parasites of vertebrates or arthropods, pollen and nectar feeders in flowers, fungus feeders, or saprophages that subsist on dead or decaying organic matter.[2][3]
The soil-dwelling Mesostigmata are not as abundant as oribatids or prostigmatids that also occur in this habitat, but they are still ubiquitous in soil and may be important predators. Larger species tend to be predators of small arthropods or arthropod eggs, whereas smaller species prey on nematodes. Size of these mesostigmatans decreases with soil depth: plant litter and humus have large species such as Veigaia (Veigaiidae), the humus-soil interface has smaller species like Dendrolaelaps (Digamasellidae) and the mineral soil has the tiny Rhodacarellus (Rhodacaridae).[6]
A few species are known from freshwater habitats, such as wet soil, phytotelmata, waterside vegetation and sewage filter-beds. These appear to move by crawling as no species are known to swim. Some species are known to prey on mosquito eggs and one species was reared on a diet of nematodes.[5]
The parasitic Mesostigmata are mostly in superfamily Dermanyssoidea. These include parasites of invertebrates (e.g. Varroidae) and of vertebrates (other families), as well as both ectoparasites (external) and endoparasites (internal).[7]
Phoresy, the temporary attachment of a smaller animal to a larger one for travel, is common in the Mesostigmata. For example, the freshwater species are phoretic on flies of families Tipulidae, Ceratopogonidae, and Culicidae.[5]
Economic importance
Varroa destructor (Varroidae) is a major pest of honey bees. It harms bees both directly by feeding on fat body tissue, and indirectly by transmitting viruses.[8]
In agriculture, soil-dwelling mesostigmatans are important predators of nematodes, springtails and insect larvae, while plant-dwelling mesostigmatans control pests such as spider mites.[4]
Evolution
The oldest known record of the group is an indeterminate Sejidae deutonymph from the mid-Cretaceous (Albian-Cenomanian) aged Burmese amber of Myanmar.[10]
Taxonomy
Taxonomy to families (Beaulieu 2011). Genus and species counts fluctuate over time.[1][11]
Family Cercomegistidae Trägårdh, 1937 (5 genera, 13 species)
Family Davacaridae Kethley, 1977 (2 genera, 4 species)
Family Pyrosejidae Lindquist & Moraza, 1993 (2 genera, 3 species)
Family Saltiseiidae Walter, 2000 (1 genus, 1 species)
Family Seiodidae Kethley, 1977 (1 genus, 1 species)
Other
Meliponopus palpiferFain & Flechtmann, 1985 has not yet been placed into a family.
Related Research Articles
Parasitiformes are a superorder of Arachnids, constituting one of the two major groups of mites, alongside Acariformes. Parasitiformes has, at times, been classified at the rank of order or suborder.
Veigaiidae is a family of mites belonging to the superorder Parasitiformes. However they are not parasitic but free-living and predatory and are found in soil and decaying organic matter. Some species are specialists of rocky shorelines. Members of this family can be distinguished by a hyaline appendage on the tarsus of the pedipalp.
Dermanyssus is a genus of mites in the family Dermanyssidae. The etymology of the word Dermanyssus is from the Greek: derma, meaning skin, and nyssein, meaning bite.
The Laelapidae are a family of mites in the order Mesostigmata. The family is also referred to in the literature as Laelaptidae, which may be the correct spelling.
Ologamasidae is a family of mites in the order Mesostigmata. There are more than 40 genera and 470 described species in Ologamasidae.
Gamasiphis is a genus of mites in the family Ologamasidae. There are more than 60 described species in Gamasiphis.
Hydrogamasellus is a genus of mites in the family Ologamasidae. There are more than 20 described species in Hydrogamasellus.
Macrochelidae is a family of mites in the order Mesostigmata.
Pachylaelaps is a genus of mites in the family Pachylaelapidae. There are more than 50 described species in Pachylaelaps.
Ameroseius is a genus of mites in the family Ameroseiidae. There are more than 60 described species in Ameroseius.
Ascidae is a family of mites in the order Mesostigmata.
Dinogamasus is a genus of mites in the family Laelapidae. Most species are associated with carpenter bees in the genus Xylocopa and are found in their acarinarium.
Rhinonyssidae is a family of mites in the order Mesostigmata. There are about 16 genera and at least 460 described species in Rhinonyssidae.
Uroseius is a genus of mites in the family Trachytidae.
Dinychidae is a family of mites in the order Mesostigmata.
Celaenopsidae is a family of mites in the order Mesostigmata.
Cercomegistidae is a family of mites in the order Mesostigmata.
Blattisociidae is a family of mites in the order Mesostigmata.
Insectolaelaps is a genus of mites in the family Digamasellidae. There are at least 20 described species in Insectolaelaps.
Trigynaspida is a suborder of mites in the order Mesostigmata. There are more than 25 families and at least 90 described species in Trigynaspida.
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