Riccardoella Limacum
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''Riccardoella limacum'' or the white snail mite is a member of the
Acari Mites are small arachnids (eight-legged arthropods) of two large orders, the Acariformes and the Parasitiformes, which were historically grouped together in the subclass Acari. However, most recent genetic analyses do not recover the two as ea ...
(mite) family which is parasitic primarily on
snail A snail is a shelled gastropod. The name is most often applied to land snails, terrestrial molluscs, terrestrial pulmonate gastropod molluscs. However, the common name ''snail'' is also used for most of the members of the molluscan class Gas ...
s. Slug mites are very small (less than 0.5 mm in length), white, and can be seen to move very rapidly over the surface of their host, particularly under the
shell Shell may refer to: Architecture and design * Shell (structure), a thin structure ** Concrete shell, a thin shell of concrete, usually with no interior columns or exterior buttresses Science Biology * Seashell, a hard outer layer of a marine ani ...
rim and near the pulmonary aperture. While once thought to be benign mucophages, more recent studies have shown that they actually subsist on the host's blood, and may bore into the host's body to feed. Studies have shown that this species name has been frequently misapplied to the more widespread ''Riccardoella oudemansi'', the white slug mite. Despite its name, ''R. limacum'' is typically a restricted parasite of snails, while ''R. oudemansi'' is the common species on slugs, although it occasionally feeds on snails too.


Hosts

Mite infection among gastropod populations varies greatly. Dense gastropod population favors infection; isolated populations may remain uninfected. Older and larger gastropods are more likely to show infection. Mites have been observed to move from host to host when hosts mate, and when gastropods congregate in moist soil and under rocks during the day. It has been shown that mites move preferentially towards fresh mucus when they travel along mucus, enabling them to follow mucus trails to new hosts. Once infected, individual gastropods take longer to mature and show reduced mating, activity, and feeding. Infected slugs and snails lay fewer eggs than uninfected individuals. Infected gastropods also show decreased winter survival rates. At least 31 species of mollusks are exploited. Common hosts include the following: Note that, as recent studies show that ''R. limacum'' is usually limited to snails, this host list deserves revision. *'' Deroceras agreste'' *''
Arianta arbustorum ''Arianta arbustorum'', sometimes known as the copse snail, is a medium-sized species of pulmonate land snail in the family Helicidae.MolluscaBase eds. (2021). MolluscaBase. Arianta arbustorum (Linnaeus, 1758). Accessed through: World Register o ...
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Arion ater The black slug (also known as black arion, European black slug, or large black slug), ''Arion ater'', is a large terrestrial gastropod mollusk in the family Arionidae, the round back slugs. Many land slugs lack external shells, having a vestigi ...
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Arion hortensis ''Arion hortensis'', also known by its common name the "garden slug", "small striped slug" or "black field slug" is a species of small air-breathing land slug, a terrestrial pulmonate gastropod mollusk in the family Arionidae, the roundback slu ...
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Cornu aspersum ''Cornu aspersum'' (syn. ''Helix aspersa'', ''Cryptomphalus aspersus''), known by the common name garden snail, is a species of land snail in the family Helicidae, which includes some of the most familiar land snails. Of all terrestrial molluscs, ...
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Helix pomatia ''Helix pomatia'', known as the Roman snail, Burgundy snail, or escargot, is a species of large, air-breathing stylommatophoran land Snails, snail native to Europe. It is characterized by a globular brown shell. It is an edible species which comm ...
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Limax maximus ''Limax maximus'' (literally, "biggest slug"), known by the common names great grey slug and leopard slug, is a species of slug in the family Limacidae, the keeled slugs.Marshall, B. (2014). Limax maximus Linnaeus, 1758. Accessed through: World ...
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Milax budapestensis Milax may refer to: * Milax, Azerbaijan * ''Milax'' (gastropod), a genus of land slugs in the family Milacidae {{Disambiguation ...
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Milax gagates ''Milax gagates'', known by the common name greenhouse slug, is a species of air-breathing, keeled, land slug, a shell-less terrestrial gastropod mollusc in the family Milacidae.Marshall, B. (2014). Milax gagates (Draparnaud, 1801). Accessed thr ...
'' *'' Milax sowerbyi'' *''
Oxychilus draparnaudi ''Oxychilus draparnaudi'', or Draparnaud's glass snail, is a species of small land snail, a Terrestrial molluscs, terrestrial pulmonate gastropod mollusc in the family Oxychilidae, the glass snails. Description ''Oxychilus draparnaudi'' is lar ...
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Taxonomy

The slug mite was first identified in 1710 by entomologist
René Antoine Ferchault de Réaumur René Antoine Ferchault de Réaumur (; ; 28 February 1683 – 17 October 1757) was a French entomologist and writer who contributed to many different fields, especially the study of insects. He introduced the Réaumur temperature scale. Lif ...
. Three species were subsequently named, though they were synonymized as ''Riccardoella limacum'' in 1946.


Life cycle

Slug mites are a one-host mite. It is possible for a mite to be born, live, and die on a single host. Mites have two sexes. Their five-stage life cycle is as follows: Females lay eggs in the host lung, and then the eggs hatch in 8–12 days as six-legged larva in the lungs of hosts and undergo three nymph stages. The whole life cycle can take place in 20 days under ideal conditions. Eggs do not hatch while the host is hibernating.


Economic impact and treatment

Slug mites are a concern for commercial and hobbyist breeders of snails; as few as six mites can sicken an individual and make it susceptible to infection by threadworms and bacteria such as ''
Pseudomonas aeruginosa ''Pseudomonas aeruginosa'' is a common Bacterial capsule, encapsulated, Gram-negative bacteria, Gram-negative, Aerobic organism, aerobic–facultative anaerobe, facultatively anaerobic, Bacillus (shape), rod-shaped bacteria, bacterium that can c ...
''. Countermeasures include regular washing and introduction of '' Hypoaspis miles,'' a predatory species of mite which feeds upon slug mites.


References


Other sources

* Baur B. and Schupbach H.U. (2008). "Parasitic mites influence fitness components of their host, the land snail arianta arbustrorum". ''Invertebrate biology'', 127 (3), 350-356 * Baur A. and Baur B. (2005). "Interpopulation variation in the prevalence and intensity of parasitic mite infection in the land snail Arianta arbustrum". ''Invertebrate biology'' 124 (3), 194-201 {{Taxonbar, from=Q3024266 Arachnids of Europe Trombidiformes Arachnids described in 1776 Taxa named by Franz von Paula Schrank