Root-knot nematodes are plant-parasitic nematodes from the genus Meloidogyne. They exist in soil in areas with hot climates or short winters. About 2000 plants worldwide are susceptible to infection by root-knot nematodes and they cause approximately 5% of global crop loss. Root-knot nematode larvae infect plant roots, causing the development of root-knot galls that drain the plant's photosynthate and nutrients. Infection of young plants may be lethal, while infection of mature plants causes decreased yield.
Androdioecy is a reproductive system characterized by the coexistence of males and hermaphrodites. Androdioecy is rare in comparison with the other major reproductive systems: dioecy, gynodioecy and hermaphroditism. In animals, androdioecy has been considered a stepping stone in the transition from dioecy to hermaphroditism, and vice versa.
Diplogasterida was an order of nematodes. It was sometimes placed in a monotypic subclass Diplogasteria, but molecular phylogenetic evidence has shown it to be embedded in the family Rhabditidae. The confusion of having a hierarchical nesting of groups that were formerly mutually exclusive has led to a profusion of names. Although completely revised taxonomy of nematodes that builds on recent classification systems as well as recent phylogenetic evidence is still necessary, most contemporary taxonomic studies now treat all groups listed under "Diplogasterina" below as a single family, Diplogastridae.
The nematodes or roundworms constitute the phylum Nematoda, with plant-parasitic nematodes also known as eelworms. They are a diverse animal phylum inhabiting a broad range of environments. Taxonomically, they are classified along with insects and other moulting animals in the clade Ecdysozoa, and unlike flatworms, have tubular digestive systems with openings at both ends. Like tardigrades, they have a reduced number of Hox genes, but their sister phylum Nematomorpha has kept the ancestral protostome Hox genotype, which shows that the reduction has occurred within the nematode phylum.
Bursaphelenchus is a genus of nematodes (roundworms) in the order Aphelenchida. Most are obligate mycophages, but some feed on wood, with two species, the red ring nematode and the pine wood nematode, economically significant as pests of coconut palms and of pine trees, respectively. Given that Bursaphelenchus species are usually hard to distinguish from one another except by trained nematologists with access to microscopes or DNA sequence analysis, the entire genus is put under quarantine in some countries. Where this is not the case however, these nematodes are becoming established as model organisms for nematode developmental biology, ecology and genetics.
Caenorhabditis japonica is a species of nematodes in the genus Caenorhabditis. Its genome was sequenced by the Genome Center at Washington University. This gonochoristic species is found in the 'Japonica' group, the sister clade to the 'Elegans' group, in the 'Elegans' supergroup.
Micoletzkya is a genus of predatory bark-beetle-associated nematodes in the family Diplogastridae. The genus was named for the Austrian nematologist Heinrich Micoletzky. As of 2013 it consists of 25 described species.
Diplogastridae, formerly Diplogasteridae, are a family of nematodes (roundworms) known from a wide range of habitats, often in commensal or parasitic associations with insects.
Pristionchus is a genus of nematodes (roundworms) in the family Diplogastridae that currently includes more than 50 described species. They are known mainly as non-parasitic associates of insects, especially beetles, while others have been reported from soil, organic matter, or rotting wood. The genus includes P. pacificus, a satellite model organism to the well-studied nematode Caenorhabditis elegans.
Pristionchus pacificus is a species of free-living nematodes (roundworms) in the family Diplogastridae. The species has been established as a satellite model organism to Caenorhabditis elegans, with which it shared a common ancestor 200–300 million years ago. The genome of P. pacificus has been fully sequenced, which in combination with other tools for genetic analysis make this species a tractable model in the laboratory, especially for studies of developmental biology.
Paratrichodorus is a genus of terrestrial root feeding (stubby-root) nematodes in the Trichodoridae family (trichorids), being one of five genera. They are economically important plant parasites and virus vectors. The females are didelphic, and are distributed worldwide.
Trichodoridae is a family of terrestrial root feeding nematodes, being one of two that constitute suborder Triplonchida. They are economically important plant parasites and virus vectors.
Trichodorus is a genus of terrestrial root feeding (stubby-root) nematodes in the Trichodoridae family (trichorids), being one of five genera. They are economically important plant parasites and virus vectors.
Sudhausia is a genus of nematodes (roundworms) of the family Diplogastridae. They live in association with dung beetles and are primarily known from Africa. Species of Sudhausia show a suite of biological features that, together, are unusual for nematodes and animals in general: hermaphrodites, which are females in form, mature to produce offspring before they are adults and thus even capable of mating, and their eggs grow in size during development. Hermaphrodites are also always live-bearing, which is unusual for nematodes under non-stressful conditions. The genus is named in honor of Walter Sudhaus, a German nematologist.
Levipalatum texanum is a free-living nematode (roundworm) in the family Diplogastridae. The species is androdioecious, consisting of self-fertile hermaphrodites which are morphologically females, and males. It is known from the south-eastern United States and has been found to live in association with scarab beetles, although it has also been baited from soil. Nematodes of this species can be cultured on bacterium Escherichia coli in the laboratory, and they are presumed to also feed on microorganisms in the wild. Levipalatum is a monotypic genus.
Nacobbus is a genus of plant-parasitic nematodes. Prevalent in North and South America, the genus Nacobbus threatens crops such as tomato, potato, quinoa and sugarbeet. They can cause so much damage that they are considered to be of quarantine importance. The morphology and biology of Nacobbus is not all that well known, although it is possible that the host—in this case, a specific crop—influences how the morphological characteristics of these nematodes are expressed.
Heydenius is a collective group genus of fossil nematodes from the Tertiary period that cannot be placed in extant genera.
Cretacimermis is a collective group genus of fossil nematodes from the Cretaceous that cannot be placed in extant genera.
Myolaimidae is a family of nematodes in the order Rhabditida. It consists of a single genus, Myolaimus Cobb, 1920.
Allodiplogaster is a genus of nematodes (roundworms) in the family Diplogastridae that currently includes about 35 described species.
