Mermithidae is a family of nematode worms that are endoparasites in arthropods. As early as 1877, Mermithidae was listed as one of nine subdivisions of the Nematoidea.[2] Mermithidae are confused with the horsehair worms of the phylum Nematomorpha that have a similar life history and appearance.

Mermithidae
Temporal range: Aptian – Recent
Mermithid from Asian hornet
Scientific classification Edit this classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Nematoda
Class: Enoplea
Order: Mermithida
Family: Mermithidae
Braun, 1883[1]

Mermithids are parasites, mainly of arthropods. Most are known from insects, but some are recorded from spiders, scorpions and crustaceans. A few are known to parasitize earthworms, leeches and molluscs,[3] and a specimen is known from a spider preserved in Baltic amber.[4]

At least 25 species are known to parasitize mosquito larvae, making them of considerable interest in biological control.[5][6] A species, probably Pheromermis vesparum, was recorded from the invasive Asian hornet (Vespa velutina) in France. The parasite was considered to be a member of the local fauna which had adapted to a new host. However, the authors concluded that the mermithid could not hamper the hornet invasion nor be used in biological control programs against this invasive species.[7]

Life history

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A mermithid questing for Dermaptera

Mermithids are wire-like and have a smooth cuticle with layers of spiral fibres. The digestive tract is similar to that of free-living nematodes only in the young larvae prior to their parasitic life; in the parasitic stages the oesophagus is disconnected from the mid-intestine, and females lack an anus. The female genital opening is at the midbody, while the male opening is at the tip and visible as one or two spicules. The eggs are laid either in water or on land, and the newly hatched larvae are free-living, as are the adults that emerge from the hosts to lay eggs.[8]

The taxonomy of the group has been confused due to poor specimen collection as well as very limited morphological characteristics, and most are discovered by entomologists rather than nematologists. Even the best-studied species, Romanomermis culicivorax, has an unclear taxonomic status.[9]

Host behavior alteration

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Mermithid nematodes alter their host's hemolymph osmolality (concentration of salt) to induce water-seeking behavior.[10]

Association with iridoviruses

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An isopod specimen infected with Isopod iridescent virus 31 and parasitized by nematoid worms

Mermithids have been found to be associated with iridoviruses in several arthropod species. Strelkomermis spiculatus have been found to transmit an iridovirus in the mosquito species Culex pipiens,[11] Culex apinicus, and Aedes aegypti.[12] Isopod iridescent virus has been found associated with Thaumamermis cosgrovei in the isopod species Porcellio scaber and Armadillidium vulgare.[13][14] An unidentified iridovirus virus has been found in the fly species Culicoides variipennis sonorensis in association with Heleidomermis magnapapula infections.[15] In all three instances, iridoviral infections occurred at a much higher rate in mermithid-parasitized individuals.[11][12][13][15] However, in the case of the interaction between C. v. sonorensis, H. magnapapula, and their iridovirus, the virus appears to kill both host and parasite before they reach maturity, impairing the mermithid's biological control of C. v. sonorensis.[15]

Included genera

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These genera are included in the family:

References

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  1. ^ Braun, M. (1883). Die tierischen Parasiten des Menschen nebst einer Anleitung zur praktischen Beschäftigung mit der Helminthologie für Studierende and Ärzte.
  2. ^ Lankester, E. Ray (1877). "Notes on the Embryology and Classification of Animal Kingdom". Quarterly Journal of Microscopical Science. 17: 449. Retrieved 2017-03-18.
  3. ^ Poinar, G. O. (1985). "Mermithid (Nematoda) parasites of spiders and harvestmen" (PDF). Journal of Arachnology. 13 (1): 121–128.
  4. ^ Poinar, George (2005). "Heydenius araneus n.sp. (Nematoda: Mermithidae), a parasite of a fossil spider, with an examination of helminths from extant spiders (Arachnida: Araneae)". Invertebrate Biology. 119 (4): 388–93. doi:10.1111/j.1744-7410.2000.tb00108.x. JSTOR 3227190.
  5. ^ Platzer, E. G. (1981). "Biological control of mosquitoes with mermithids". Journal of Nematology. 13 (3): 257–62. PMC 2618106. PMID 19300759.
  6. ^ Martinet, Jean-Philippe; Aatif, Issam; Depaquit, Jérôme (2023). "Three Aedes species infested by mermithids in France". Parasite. 30: 12. doi:10.1051/parasite/2023013. PMC 10081132. PMID 37026735.  
  7. ^ Villemant, Claire; Zuccon, Dario; Rome, Quentin; Muller, Franck; Poinar, George O.; Justine, Jean-Lou (2015). "Can parasites halt the invader? Mermithid nematodes parasitizing the yellow-legged Asian hornet in France". PeerJ. 3: e947. doi:10.7717/peerj.947. PMC 4451032. PMID 26038716.
  8. ^ Rubzov, I. A. (1972). "Aquatic Mermithidae of the Fauna of the USSR", Vol. 1. (Zoological Institute, Academy of Science USSR).
  9. ^ Petersen, J. J. (1985) "Nematodes as biological control agents: Part 1. Mermithidae", pp 307–344. In: Baker, J. R. & Muller, R. (eds). Advances in Parasitology. Academic Press, London.
  10. ^ C. M., Williams (2004). "Increased haemolymph osmolality suggests a new route for behavioural manipulation of Talorchestia quoyana (Amphipoda: Talitridae) by its mermithid parasite". Functional Ecology. 18 (5): 685–691. doi:10.1111/j.0269-8463.2004.00910.x.
  11. ^ a b Muttis, Evangelina; Micieli, María Victoria; Urrutia, María Inés; García, Juan José (2015-07-01). "Transmission of a pathogenic virus (Iridoviridae) of Culex pipiens larvae mediated by the mermithid Strelkovimermis spiculatus (Nematoda)". Journal of Invertebrate Pathology. 129: 40–44. doi:10.1016/j.jip.2015.05.011. hdl:11336/10236. ISSN 0022-2011.
  12. ^ a b Muttis, E.; Micieli, M. V.; Bonica, M. B.; Ghiringhelli, P. D.; García, J. J. (2020-04-01). "Mosquito Iridescent Virus: New Records from Nature and Infections Using Strelkovimermis spiculatus (Mermithidae) as a Vector Under Laboratory Conditions". Neotropical Entomology. 49 (2): 268–274. doi:10.1007/s13744-019-00755-9. ISSN 1678-8052.
  13. ^ a b Poinar, Jr., George O.; Hess, Roberta T.; Cole, Anabel (1980). "Replication of an Iridovirus in a Nematode (Mermithidae)". Intervirology. 14 (5–6): 316–320. doi:10.1159/000149202. ISSN 1423-0100.
  14. ^ Poinar, George O. (1981-05-01). "Thaumamermis cosgrovei n. gen., n. sp. (Mermithidae: Nematoda) parasitizing terrestrial isopods (Isopoda: Oniscoidea)". Systematic Parasitology. 2 (4): 261–266. doi:10.1007/BF00009346. ISSN 1573-5192.
  15. ^ a b c Mullens, Bradley A.; Velten, Robert K.; Federici, Brian A. (1999-03-01). "Iridescent Virus Infection in Culicoides variipennis sonorensis and Interactions with the Mermithid Parasite Heleidomermis magnapapula". Journal of Invertebrate Pathology. 73 (2): 231–233. doi:10.1006/jipa.1998.4838. ISSN 0022-2011.
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