Micoletzkya
{{Short description|Genus of roundworms}}
{{Taxobox
| regnum = Animalia
| phylum = Nematoda
| classis = Chromadorea
| ordo = Rhabditida
| familia = Diplogastridae
| genus = Micoletzkya
| genus_authority = Weingärtner 1955
}}
Micoletzkya is a genus of predatory bark-beetle-associated nematodes in the family Diplogastridae.{{cite journal | last1 = Sudhaus | first1 = W. | last2 = von Lieven | first2 = A.F. | year = 2003 | title = A phylogenetic classification and catalogue of the Diplogastridae (Secernentea, Nematoda) | journal = Journal of Nematode Morphology and Systematics | volume = 6 | pages = 43–89 }}{{cite journal | last1 = Mayer | first1 = W.E. | last2 = Herrmann | first2 = M. | last3 = Sommer | first3 = R.J. | year = 2009 | title = Molecular phylogeny of beetle associated diplogastrid nematodes suggests host switching rather than nematode-beetle coevolution | journal = BMC Evolutionary Biology | volume = 9 | page = 212 | doi=10.1186/1471-2148-9-212| pmid = 19703296 | pmc = 2737313 | doi-access = free }} The genus was named for the Austrian nematologist Heinrich Micoletzky. As of 2013 it consists of 25 described species.{{cite journal | last1 = Susoy | first1 = Vladislav | last2 = Kanzaki | first2 = Natsumi | last3 = Herrmann | first3 = Matthias | year = 2013 | title = Description of the bark beetle associated nematodes Micoletzkya masseyi n. sp and M. japonica n. sp (Nematoda: Diplogastridae) | journal = Nematology | volume = 15 | issue = 2| pages = 213–231 | doi=10.1163/15685411-00002672}}
Ecology and life history
Nematodes of Micoletzkya live in symbiosis with bark beetles.Rühm, W. 1956. Die Nematoden der Ipiden. Parasitologische Schriftenreihe No. 6: 1–437. The hosts include economically important species across North America and Europe such as the mountain pine beetle Dendroctonus ponderosae and European spruce bark beetle Ips typographus.Massey, C.L. 1974. Biology and taxonomy of nematode parasites and associates of bark beetles in the United States. Agriculture Handb U S Dep Agric No. 446: 1–233.{{cite journal | last1 = Susoy | first1 = V. | last2 = Herrmann | first2 = M. | year = 2014 | title = Preferential host switching and codivergence shaped radiation of bark beetle symbionts, nematodes of Micoletzkya (Nematoda: Diplogastridae) | journal = Journal of Evolutionary Biology | volume = 27 | issue = 5| pages = 889–898 | doi=10.1111/jeb.12367| pmid = 24731122 | doi-access = free }} The life history of the nematodes is closely linked to that of their hosts. Infective (dauer) larvae of Micoletzkya attach themselves onto the body surface of a beetle for transmission and resume their development in host breeding galleries. In the bark beetle galleries, nematodes go through a few free-living generations, presumably feeding on beetle-associated microorganisms and other nematodes, after which dauer larvae develop and attach to newly emerging bark beetles for transmission.
Host specificity and speciation
Micoletzkya nematodes are remarkably host specific, with most species found in association with only a single host species. Nematodes of this genus are vertically transmitted within host populations, which fosters cospeciation with bark beetles and adaptation to particular groups of hosts. Phylogenetic evidence suggests that diversification of the genus was largely influenced by the evolutionary radiation of bark beetles.
Mouth dimorphism
Like many other members of the diplogastrid family,{{Cite journal | doi = 10.7554/eLife.05463 | last1 = Susoy | first1 = V. | last2 = Ragsdale | first2 = E.J. | last3 = Kanzaki | first3 = N. | last4 = Sommer | first4 = R.J. | year = 2015 | title = Rapid diversification associated with a macroevolutionary pulse of developmental plasticity | journal = eLife | volume = 4 | pages = e05463 | pmid = 25650739 | pmc=4357287 | doi-access = free }} Micoletzkya nematodes have movable opposing teeth and show a mouth dimorphism. Dimorphic species of the genus can express two alternative mouth phenotypes: stenostomatous (narrow mouth and small teeth) and eurystomatous (wide mouth and large teeth).{{cite journal | last1 = Fürst | last2 = von Lieven | first2 = A. | last3 = Sudhaus | first3 = W. | year = 2000 | title = Comparative and functional morphology of the buccal cavity of Diplogastrina (Nematoda) and a first outline of the phylogeny of this taxon | journal = Journal of Zoological Systematics and Evolutionary Research | volume = 38 | pages = 37–63 | doi=10.1046/j.1439-0469.2000.381125.x| doi-access = free }} The two alternative phenotypes are thought to represent a resource polyphenism, or specialized for feeding on different foods, such as microorganisms and other nematodes respectively.{{cite journal | last1 = Serobyan | first1 = V. | last2 = Ragsdale | first2 = E. J. | last3 = Sommer | first3 = R. J. | year = 2014 | title = Adaptive value of a predatory mouth-form in a dimorphic nematode | journal = Proceedings of the Royal Society B: Biological Sciences | volume = 281 | issue = 1791 | page = 20141334 | doi=10.1098/rspb.2014.1334| pmid = 25080344 | pmc = 4132687 }}
Isolation and culturing
Micoletzkya adults and larvae can be found in breeding galleries of bark beetles; dauer juveniles of the nematodes can be isolated from dispersing beetles. Many Micoletzkya species are cultured using bacteria; some species can be cultured using C. elegans and other nematodes as food. At 23 °C, the generation time of Micoletzkya is about 10 days.