Family Tylenchidae

                                             Rev 11/03/21

Classification:

 Nematoda

Rhabditida

Tylenchina

                         Tylenchuloidea
        

Tylenchidae Orley, 1880

Synonyms: 

Atylenchidae Skarbilovich, 1959

Ecphyadophoridae Skarbilovich, 1959 

Boleodoridae Khan, 1964 

Tylodoridae Paramonov, 1967 

Key to the Tylenchidae

Morphology and Anatomy: 

Usually slender, elongate, small species. Sexes similar. Stylet usually small, delicate.

photomicrograph by Howard Ferris and Sam Woo, UC Davis.

 Esophagus with slender procorpus, median bulb either well-developed, weakly developed or even not obvious; long, slender isthmus, esophageal glands symmetrically arranged, pyriform, rarely with slight overlap of intestine. 

Female: One gonad, prodelphic; rarely, two gonads; columned uterus with four rows. Tail long, conoid to filiform.

Male: Caudal alae adanal, small, occasionally lacking. 

 photomicrograph by Howard Ferris and Sam Woo, UC Davis

Most of the characteristics of the species of Tylenchidae conform with the definition of primitivity and as expressed by Luc et al. (1987):  small stylet, delicate labial framework; amphid openings from small to elongate, sinuousoid or straight, extending posteriad longitudinally; median bulb spindle shaped, small, delicate or rounded, muscular; esophageal glands symmetrically arranged, pyriform; tail elongate, long many of which are generally considered to be ancestral characters (Qing and Bert, 2017).. 

The family Tylenchidae is one of the most diverse and cosmopolitan of the Tylenchina; apparently actively evolving in some characters, such as the amphids moving from large elongate post labial structures, varying to arc-shaped or oval pits limited to the labial plate, or even small elliptical apertures near the oral opening (Miculenchus, Ecphyadophora), with many links and relationships with other groups (i.e. Tylodorus with characteristics of the Dolichodoridae; Filenchus with characteristics of the Anguinidae, etc.). 

As of 2019, the family Tylenchidae contains over 400 species (Siddiqi, 2000; Geraert, 2008) with high ecological diversity and abundance. Many species are poorly described on the basis of morphological characters and a limited number of specimens.  Molecular data are improving definition of species characteristics (Panahandeh et al., 2018).

The family is most closely related to the Anguinidae, which were formerly considered part of the Tylenchidae (Siddiqi, 1971).  The families differ in that there are small elliptical amphids in Anguinidae, which also have elongated, axial spermatheca, large sperms with prominent cytoplasm, and females with a long post-uterine branch of the gonad (more than two body diameters at vulva level). 

Key to the Genera of Tylenchidae

adapted from Geraert and Raski, 1987

Distribution: 

Commonly occurring in most soils. Feed on algae, mosses, lichens and plant roots. As an example: Soil nematodes were studied in three spruce forests in the Czech Republic from 1988 to 1991. A total of 74 species occurred, most belonged to the orders Tylenchida, Rhabditida and Dorylaimida. The most abundant nematodes were the mycophytophagous species of the family Tylenchidae followed by bacteriophages, especially by those in the order Rhabditida. 

Members of the Tylenchidae frequently constitute up to 30% of the individuals in a soil sample.(Ferris and Bongers, 2006)

Economic Importance: 

Probably fairly small. Most reports are about occurrence and abundance rather than documenting any effects on growth.  Arguably, the benefits of soil food web stimulation and participation in nutrient cycles may outweigh any economic damage to crops.

Feeding: 

Ectoparasites of plant roots, root hairs, algae, etc. 

 Yeates et al. (1993a):  placed the Tylenchidae in the following feeding groups:

• Aglenchus: plant feeder (epidermal cell and root feeder),

• Cephalenchus: plant feeder (ectoparasite),

• Coslenchus: (epidermal cell and root feeder),

• Filenchus: (epidermal cell and root feeder),

• Malenchus: (epidermal cell and root feeder),

• Tylenchus: plant feeder (algal, lichen (algal or fungal component), or moss feeders that feed by piercing), or hyphal feeder (?).

• Yeates et al. (1993b):  classified Tylenchus spp. as "plant associated", indicating that they were found in the rhizospheres of plants. 

• Okada et al (2002 and 2003) have demonstrated that Filenchus misellus is a fungal-feeding nematode and able to reproduce on a range of fungi.

Hosts: 

Nematodes in this family are associated with algae, mosses, lichens, fungi, and plant roots. Some of the species are considered as weak parasites of plants (Siddiqi, 2000).

The following is an initial compilation of feeding habits of Tylenchidae by Erik Schaper while working on an MSc-project under the supervision of Tom Bongers (Laboratory of Nematology, Wageningen University)..

Project Title: "Tylenchidae, plant parasites or fungal feeders?".

Objectives:

1. To find the available literature about the subject (the feeding biology of the Tylenchidae (sensu lato)).
2. To do feeding experiments to find a probable food source for the Tylenchidae (sensu lato).

Literature Review:

• Baujard (1995):  Coslenchus franklinae was cultured in the laboratory, but on what medium or plant is not clear.
• Ferris et al. (1996):  Tylenchus davainei was not cultivable on the fungus species Rhizoctonia.
•  Gowen (1970):  Tylenchus emarginatus ( = Cephalenchus emarginatus) fed and reproduced on sitka spruce seedlings growing in water agar without obviously damaging them.
•  Khera and Zuckermann (1962):  Aglenchus costatus ( = Coslenchus costatus) propagated rapidly on alfalfa callus tissue at 23°C, but it failed to propagate on other tissue cultures (tomato, broccoli, carrot, cabbage, rye and corn).
• Khera and Zuckermann (1963):  1) Aglenchus agricola (Cephalenchus emarginatus (Hooper, 1974)) does feed on cauliflower and cabbage for a maximum period of 6 minutes. It does not feed on broccoli, kohlrabi, radish, carrot, dill, tomato, lettuce, beet, alfalfa, rye grass and marigold.  2) Malenchus bryophilus does feed on cabbage for a long period and on dill and alfalfa for a maximum period of 2,5 minutes. It does not feed on broccoli, cauliflower, kohlrabi, radish, carrot, tomato, lettuce, beet, rye grass and marigold.
• Micoletzky (1925):  Tylenchus spp. are more or less regularly feeding on algae.
• Sutherland (1967):  Tylenchus emarginatus ( = Cephalenchus emarginatus) fed and reproduce as a migratory ectoparasite on the roots of seven species of conifer (Picea abies, P. glauca, P. mariana, P. rubens, Pinus banksiana, P. sylvestris, P. resinosa), but the nematode was unable to feed or reproduce on ten species of soil-borne fungi (Cylindrocarpon radicicola, Cylindrocladium scoparium, Rhizoctonia solani, Trichoderma lignorum, Zygorhynchus moelleri, Chaetomium sp., Fusarium sp., Pestolotia sp., Pythium sp., Sporobolomyces sp.).
• Thorne (1961):  1) Tylenchus spp. frequently are among the most numerous nemas found in soil from the rhizosphere of plants. However, they have not been observed as either ectoparasites or endoparasites. Their small, strong spears indicate they probably feed on either root hairs or fungal mycelia.  2) Coslenchus cancellatus was found infesting roots of peony on which they caused gall-like swellings. Cobb (1925) observed this, but he failed to record the source of his material.
• Wood (1971):  1) Coslenchus costatus was observed feeding and reproducing on seedlings (fescue tussock and rye grass), on alfalfa callus tissue, on fungi (Phoma sp., Rhizoctonia solani and Ulocladium atrum), and on mosses (Tortula princeps and Bryum sp.).  2) Tylenchus maiakus (nomen nuda) was observed feeding and reproducing on seedlings.  3) Tylenchus rikus (nomen nuda) was observed feeding and reproducing on fungi.  4) Tylenchus sp. was observed feeding on fungi and mosses.
• Wood (1973a):  Coslenchus costatus was observed feeding and reproducing on seedlings of fescue tussock and rye grass, on alfalfa callus tissue and moss (Tortula princeps and Bryum sp.). It was observed feeding on fungi, but it was only in two occasions for a short time.
• Wood (1973b):  Coslenchus costatus was observed feeding ectoparasitically on root hairs, epidermal root cells and occasionally on sloughed root-cap cells of rye grass seedlings growing in agar. It was observed feeding on seedlings of white clover, suckling clover, rye grass, crested dogstail, Yorkshire fog, timothy, goosegrass, sweet vernal, browntop, cocksfoot, fescue tussock, chewings fescue.

Additionally:

Okada et al (2002 and 2003) have experimentally demonstrated that Filenchus misellus is a fungal-feeding nematode and able to reproduce on a range of fungi.

Life Cycle: 

Little is known of the life history of most species, but in so far as known, they have no specialized cycles, resting, or resistant stages.

Damage: 

Relatively slight, small stylets penetrating only thin cell walls.

Management: 

References: 

Andrássy, I (1976), Aglenchus costatus, C.I.H. Descriptions of plant-parasitic nematodes, set 6, No. 80, 2 pp.

Baujard, P. (1995), Laboratory methods used for the study of the ecology and pathogenicity of Tylenchida, Longidoridae and Trichodoridae from rainy and semi-arid tropics of West Africa, Fundamental and Applied Nematology, 18, 63-66

Cobb, N.A. (1925), Biological relationships of the mathematical series 1, 2, 4, etc., Chapter 15 in: Contributions to a Science of Nematology,

Ferris, H., and Bongers, T. 2006. Nematode indicators of organic enrichment. Journal of Nematology 38:3–12.

Ferris, H., Venette, R.C., Lau, S.S. (1996), Dynamics of nematode communities in tomatoes grown in convential and organic farming systems, and their impact on soil fertility, Applied Soil Ecology, 3, 161-175

Geraert, E. 2008. The Tylenchidae of the world: identification of the family Tylenchidae (Nematoda). Gent, Academia Press: 540 pp

Geraert & Raski (1987)  Rev. Nematol. 10(2):143-161.

Gowen, S.R. (1970), Observations on the fecundity and longevity of Tylenchus emarginatus on sitka spruce seedlings at different temperatures, Nematologica, 13, 267-272

Hanel, Ladislav. 1996. Comparison of soil nematode communities in three spruce forests Boubin Mount, Czech Republic. Biologia (Bratislava) 51. 

Hooper, D.J. (1974), Cephalenchus emarginatus, C.I.H. Descriptions of plant-parasitic nematodes, Set 3, No. 35, 2 pp.

Khera, S., Zuckermann, B.M. (1962), Studies on the culturing of certain ectoparasitic nematodes on plant callus tissue, Nematologica, 8, 272-274

Khera, S., Zuckermann, B.M. (1963), In vitro studies of host-parasite relationships of some plant-parasitic nematodes, Nematologica, 9, 1-6

Micoletzky, H. (1925), Die freilebenden Süsswasser- und Moornematoden Dänemarks nebst Anhang über Amöbesporidien und andere Parasiten bei freilebenen Nematoden, D. Kgl. Danske Vidensk. Selsk. Skrifter, Naurvidensk. og Mathem., ser 8, 10, 57-310

Qing, X., Bert, W. 2017. Redefinition of Genus Malenchus Andrassy, 1968 (Tylenchomorpha: Tylenchidae) with Additional Data on Ecology. J. Nematology 49:189-206.

Siddiqi, M.R. (1986), Tyenchida, parasites of plants and insects, CAB, Slough, 645 pp.

Siddiqi, M.R. 2000. Tylenchida, Parasites of Plants and Insects, 2nd ed. Wallingford, UK: CAB International, 833 pp.

Sutherland, J.R. (1967), Parasitism of Tylenchus emarginatus on conifer seedling roots and some observations on the biology of the nematode, Nematologica, 13, 191-196

Thorne, G. (1961), Tylenchinae, chapter 5 in: Principles of Nematology, McGraw-Hill Book Company Inc., New York - Toronto - London, 553 pp.

Wood, F.H. (1971), Studies on the biology of soil-dwelling nematodes from tussock grassland, Ph.D. thesis, University of Canterbury, New Zealand, 286 pp.

Wood, F.H. (1973a), Life cycle and host-parasite relationships of Aglenchus costatus (de Man, 1921) Meyl, 1961 (Nematoda, Tylenchidae), New Zealand Journal of Agricultural Research, 16, 373-380

Wood, F.H. (1973b), Nematode feeding relationships, feeding relationships of soil-dwelling nematodes, Soil Biology and Biochemistry, 5, 593-601

Yeates, G.W., Bongers, T., Goede, R.G.M. de, Freckman, D.W., Georgieva, S.S. (1993a), Feeding habits in soil nematode families and genera - an outline for soil ecologists, Journal of Nematology, 25 (3): 315-331

Yeates, G.W., Wardle, D.A., Watson, R.N. (1993b), Relationships between nematodes, soil microbial biomass and weed-management strategies in maize and asparagus cropping systems, Soil Biology and Biochemistry, 25, 869-876

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