Nacobbus

{{Short description|Genus of roundworms}} {{Automatic_taxobox | image = Nacobbus aberrans.jpg | parent_authority = Chitwood in Chitwood & Chitwood, 1950 | taxon = Nacobbus | authority = Thorne & Allen, 1944 | synonyms = | subdivision_ranks = Species | subdivision = *''Nacobbus aberrans'' <small>(Thorne, 1935)</small> *''Nacobbus dorsalis'' <small>Thorne & Allen, 1944</small> }}

'''''Nacobbus''''' is a genus of plant-parasitic nematodes.<ref name="SinghHodda2013">{{cite journal| vauthors = Singh SK, Hodda M, Ash GJ |title=Plant-parasitic nematodes of potential phytosanitary importance, their main hosts and reported yield losses|journal=EPPO Bulletin|volume=43|issue=2|year=2013|pages=334–374|doi=10.1111/epp.12050}}</ref> 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.<ref>{{cite journal | vauthors = Lax P, Doucet ME, Di Rienzo JA |year=2006 |title=Morphometric comparative study among isolates of ''Nacobbus aberrans'' (Thorne, 1935) Thorne & Allen, 1944 from Argentina |url=https://revistaselectronicas.ujaen.es/index.php/jnms/article/view/162 |journal=Journal of Nematode Morphology and Systematics |volume=9 |issue=2 |pages=83–93}}</ref> __TOC__

==Taxonomy== Two type species of ''Nacobbus'', ''Nacobbus aberrans'' and ''Nacobbus dorsalis'', were identified in 1944 by Thorne and Allen along with two additional possible species, ''N. batatiformis'' and ''N. serendipiticus''.<ref name="Manzanilla-López2010">{{cite journal| vauthors = Manzanilla-López R |title=Speciation within Nacobbus: consilience or controversy?|journal=Nematology|volume=12|issue=3|year=2010|pages=321–334 |doi=10.1163/138855409X12584547412734}}</ref> In 1970, Sher classified ''N. batatiformis'' and ''N. serendipiticus'' under the species ''Nacobbus aberrans''. ''N. aberrans'' and ''N. dorsalis'' were concluded to be the only two species of ''Nacobbus'' and were differentiated by morphological characteristics. Today, the classification of ''Nacobbus'' into these two species is generally accepted as accurate. However, recent studies focused on morphology and host-range suggest that this classification may need to be reevaluated. Proper classification of the genus is crucial in order to most effectively manage and quarantine them.{{citation needed|date=November 2022}}

==Life cycle== In terms of feeding strategy, ''Nacobbus'' is classified as a false root-knot nematode because it is both migratory endoparasitic and sedentary endoparasitic.<ref name="Eves-van den AkkerLilley2014">{{cite journal | vauthors = Eves-van den Akker S, Lilley CJ, Danchin EG, Rancurel C, Cock PJ, Urwin PE, Jones JT | title = The transcriptome of Nacobbus aberrans reveals insights into the evolution of sedentary endoparasitism in plant-parasitic nematodes | journal = Genome Biology and Evolution | volume = 6 | issue = 9 | pages = 2181–94 | date = August 2014 | pmid = 25123114 | doi = 10.1093/gbe/evu171 |pmc=4202313 | doi-access = free }}</ref> It is the only known nematode to do so; all others employ either one strategy or the other. In'' Nacobbus'', each strategy is employed at different stages in the life cycle.<ref>{{cite journal | vauthors = Vovlas N, Nico AI, De Luca F, De Giorgi C, Castillo P | title = Diagnosis and Molecular Variability of an Argentinean Population of Nacobbus aberrans with Some Observations on Histopathology in Tomato | journal = Journal of Nematology | volume = 39 | issue = 1 | pages = 17–26 | date = March 2007 | pmid = 19259470 | pmc = 2586475 }}</ref> Immature males and females are migratory whereas mature females are sedentary. The life cycle of ''Nacobbus'' begins when they hatch from eggs in the soil and migrate through roots and soil until mature, causing necrotic lesions. Then, mature females form a feeding site called a syncytium, which is composed of plant material and formed in healthy root tissue. There the females produce eggs and lay them in the soil to hatch.{{citation needed|date=November 2022}}

== References == {{Reflist}}

Category:Secernentea genera Category:Tylenchida Category:Plant pathogenic nematodes