Mermithidae Temporal range: | |
---|---|
Mermithid from Asian hornet | |
Scientific classification | |
Domain: | Eukaryota |
Kingdom: | Animalia |
Phylum: | Nematoda |
Class: | Enoplea |
Order: | Mermithida |
Family: | Mermithidae Braun, 1883 [1] |
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.
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]
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]
Mermithid nematodes alter their host's hemolymph osmolality (concentration of salt) to induce water-seeking behavior. [10]
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]
These genera are included in the family:
Mosquitoes, the Culicidae, are a family of small flies consisting of 3,600 species. The word mosquito is Spanish and Portuguese for little fly. Mosquitoes have a slender segmented body, one pair of wings, three pairs of long hair-like legs, and specialized, highly elongated, piercing-sucking mouthparts. All mosquitoes drink nectar from flowers; females of some species have in addition adapted to drink blood. The group diversified during the Cretaceous period. Evolutionary biologists view mosquitoes as micropredators, small animals that parasitise larger ones by drinking their blood without immediately killing them. Medical parasitologists view mosquitoes instead as vectors of disease, carrying protozoan parasites or bacterial or viral pathogens from one host to another.
Nematomorpha are a phylum of parasitoid animals superficially similar to nematode worms in morphology, hence the name. Most species range in size from 50 to 100 millimetres, reaching 2 metres (79 in) in extreme cases, and 1 to 3 millimetres in diameter. Horsehair worms can be discovered in damp areas, such as watering troughs, swimming pools, streams, puddles, and cisterns. The adult worms are free-living, but the larvae are parasitic on arthropods, such as beetles, cockroaches, mantises, orthopterans, and crustaceans. About 351 freshwater species are known and a conservative estimate suggests that there may be about 2000 freshwater species worldwide. The name "Gordian" stems from the legendary Gordian knot. This relates to the fact that nematomorphs often coil themselves in tight balls that resemble knots.
Wolbachia is a genus of gram-negative bacteria infecting many species of arthropods and filarial nematodes. The symbiotic relationship ranges from parasitism to obligate mutualism. It is one of the most common parasitic microbes of arthropods, and is possibly the most widespread reproductive parasite bacterium in the biosphere. Its interactions with hosts are complex and highly diverse across different host species. Some host species cannot reproduce, or even survive, without Wolbachia colonisation. One study concluded that more than 16% of neotropical insect species carry bacteria of this genus, and as many as 25 to 70% of all insect species are estimated to be potential hosts.
Culex or typical mosquitoes are a genus of mosquitoes, several species of which serve as vectors of one or more important diseases of birds, humans, and other animals. The diseases they vector include arbovirus infections such as West Nile virus, Japanese encephalitis, or St. Louis encephalitis, but also filariasis and avian malaria. They occur worldwide except for the extreme northern parts of the temperate zone, and are the most common form of mosquito encountered in some major U.S. cities, such as Los Angeles.
The discipline of medical entomology, or public health entomology, and also veterinary entomology is focused upon insects and arthropods that impact human health. Veterinary entomology is included in this category, because many animal diseases can "jump species" and become a human health threat, for example, bovine encephalitis. Medical entomology also includes scientific research on the behavior, ecology, and epidemiology of arthropod disease vectors, and involves a tremendous outreach to the public, including local and state officials and other stake holders in the interest of public safety.
The nematodes, roundworms or eelworms constitute the phylum Nematoda. They are a diverse animal phylum inhabiting a broad range of environments. Most species are free-living, feeding on microorganisms, but many species are parasitic. The parasitic worms (helminths) are the cause of soil-transmitted helminthiases.
Paleoparasitology is the study of parasites from the past, and their interactions with hosts and vectors; it is a subfield of paleontology, the study of living organisms from the past. Some authors define this term more narrowly, as "Paleoparasitology is the study of parasites in archaeological material." K.J. Reinhard suggests that the term "archaeoparasitology" be applied to "... all parasitological remains excavated from archaeological contexts ... derived from human activity" and that "the term 'paleoparasitology' be applied to studies of nonhuman, paleontological material." This article follows Reinhard's suggestion and discusses the protozoan and animal parasites of non-human animals and plants from the past, while those from humans and our hominid ancestors are covered in archaeoparasitology.
Mandayam Osuri Tirunarayana Iyengar was an Indian medical entomologist who worked on management of filaria and malaria vectors. He was employed as an entomologist in the Department of Malaria Research, Bengal. The mermithid parasite Romanomermis iyengari and the mosquito species Culex iyengari are named after him.
Culex quinquefasciatus, commonly known as the southern house mosquito, is a medium-sized mosquito found in tropical and subtropical regions of the world. It is a vector of Wuchereria bancrofti, avian malaria, and arboviruses including St. Louis encephalitis virus, Western equine encephalitis virus, Zika virus and West Nile virus. It is taxonomically regarded as a member of the Culex pipiens species complex. Its genome was sequenced in 2010, and was shown to have 18,883 protein-coding genes.
Culicoides variipennis is a 1 millimetre (0.039 in) long biting midge. It is a part of the subgenus Monoculicoides and has many subspecies. Found in North America, C. variipennis transmits Bluetongue virus, African horse sickness virus, akabane virus, and epizootic hemorrhagic disease.
Setaria is a genus of parasitic roundworms that infect domesticated mammals such as pigs, camels, cattle and horses. Some species also infect wild mammals such as deer and antelope. The genus consists of about 43 species. Members of the genus are uniquely parasites in the abdominal cavity of the body. They are mostly large-sized roundworms, possessing an elaborate head (cephalic) region that is characterised by spines, presence of four lips, and well-guarded mouth. Little is known about their pathogenic effects, but some are known to affect the nervous system and eye. The larval infective forms are transmitted from one animal to another by the bite of mosquitoes and flies. In addition Setaria marshalli can be transmitted from the womb to new-born calf.
Chloriridovirus is a genus of viruses, in the family Iridoviridae. Diptera with aquatic larval stage, mainly mosquitoes, lepidoptera, and orthoptera insects serve as natural hosts. There are five species in this genus. Diseases associated with this genus include: yellow-green iridescence beneath the epidermis. Death rates are highest in the fourth instar. Viruses within this genus have been found to infect mosquito larvae, in which they produce various iridescent colors.
Iridovirus is a genus of viruses in the family Iridoviridae. Arthropods serve as natural hosts. Currently, only two species are placed in this genus. Invertebrate iridescent virus 6 (IIV-6) was recognised as the type species until such a designation was abolished. IIV-6 is hosted by mosquitos and usually causes covert (inapparent) infection that reduces fitness. The remaining species Invertebrate iridescent virus 31 (IIV-31) is hosted by isopods and causes patent (apparent) infection characterised by blue to bluish-purple iridescence and a shortened lifespan.
Heydenius is a collective group genus of fossil mermithid nematodes from the Tertiary period that cannot be placed in extant genera.
Cretacimermis is a collective group genus of fossil mermithid nematodes from the Cretaceous that cannot be placed in extant genera.
Reesimermis nielseni is a nematode in the family Mermithidae. It is a parasite of the larvae of mosquitoes, spending part of its life cycle in its host's body cavity and part in the water as a free-living worm. It has been investigated as a biological pest control agent to control mosquitoes.
Allantonematidae is a family of insect-parasitic nematodes from the order Tylenchida. Allantonematid nematodes infect a variety of insects including beetles, butterflies, flies, thrips, ants, and more. For instance, the nematode Howardula aoronymphium parasitizes mushroom-feeding fruit flies, Formicitylenchus oregonensis parasitizes carpenter ants, and Metaparasitylenchus hypothenemi parasitizes a pest of coffee beans, the coffee berry borer.
Iridovirus armadillidium1, known formerly as Invertebrate iridescent virus 31 (IIV-31) and informally as isopod iridovirus, is a species of invertebrate iridescent virus in the genus Iridovirus. Oniscidea serve as hosts. Infection is associated with decreased responsiveness in the host, increased mortality and the emergence of an iridescent blue or bluish-purple colour due to the reflection of light off a paracrystalline arrangement of virions within the tissues.
Mermis is a genus of nematodes belonging to the family Mermithidae.
Lokern virus (LOKV) is a single-stranded, negative sense, tri-segmented RNA virus. It is a subtype of the Bunyamwera virus (BUNV) and closely related to the Main Drain virus (MDV). The virus is a natural reassortment that received its S and L segments from MDV while its M segment shows a relatively low percentage of nucleotide identity in relation to any other orthobunyavirus, suggesting it came from an unknown or extinct virus.