Rev 02/17/2024

 Foliar Nematodes Classification Hosts
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            Aphelenchoides Fischer, 1894

Type species of the genus: Aphelenchoides kuehnei Fischer, 1894

As of 2017 there were more than 200 nominal species assigned to the genus (Esmaeli et al., 2017).  Many are poorly described based on morphological and anatomical characters alone and are difficult to identify (de Jesus et al., 2016).

 Species of Aphelenchoides occur in soil, decaying plant residues, moss, and on the surfaces of rocks and trees, and in associations with arthropods. Many of the species are mycophagous but a few have importance importance as ecto- and endoparasites of plants. The major plant-parasitic species include A. besseyi Christie, 1942, A. fragariae (Ritzema Bos, 1890) Christie, 1932 and A. ritzemabosi (Schwartz, 1911) Steiner & Buhrer, 1932, parasitising rice, strawberry, ornamental and other plants (Golhasan et al., 2016).


Allen provided a key to the four important species related to A. fragariae.  The key is useful in that it provides gross characters for separating the four species, but Sanwal's more detailed key would be necessary for more precise diagnosis.

1.  Head swollen, wider than neck, 4 lines in wing area............2

     Head not swollen, 2 lines in wing area................A. fragariae.

2.  Length of post-uterine branch 5 or more times body width...3

     Length of post-uterine branch less than 4 times body width......A. besseyi.

3.  Tail bluntly rounded, with a single ventral spine.....A. subtenuis.

    Tail terminus peg-like, with 4 small mucrons........A. ritzemabosi.

[From:  Allen, M.W. 1952. ]

Sanwal listed 33 species and provided a key in 1961 (Canadian J. Zool. 39:  143-148); there arearound 175 species describedas of 2018 (Aliramaji et al., 2018).

The term "foliar nematodes" is the common name of plant-parasitic forms in the genus Aphelenchoides.  However, although some species of the genus are important plant pests, others are found in, and can be recovered from, soil, mosses, mushrooms and decaying organic materials (Aliramaji et al., 2018).  Many of the species are fungivores or facultative funcgivores.

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Morphology and Anatomy:

Species identification is difficult due to poor older descriptions and unavailable type material. Molecular data are unavailable for most species, especially those described earliest. The relatively conserved morphology andlack of qualitative diagnostic morphological features further complicates Aphelenchoides species identification. However.the recently described species usually include molecular data, which is very useful for taxonomic comparisons of morphologically close species (Mobasseri et al., 2018).

  • Body length 0.5-1.2 mm long, and slender. Lip region usually slightly offset from body contour.
  • Nematodes in this genus have a large metacorpus.
  • Dorsal overlap of the esophageal glands over the intestine. 
  • Slender stylet with small, distinct knobs.
  • Dorsal esophageal gland opens into lumen of esophagus in metacorpus, just anterior to the pump chamber.
  • Subventral esophageal glands open into lumen of esophagus in metacorpus, posterior to the pump chamber.
  • Tails of both sexes never elongate-filiform, but usually more or
    less tapering, conical and frequently ending in one or more mucrons..

Ref: Nickle, 1970

Go To Dictionary of Terminology 


  • Monodelphic, prodelphic, usually with well-developed postuterine sac.
  • Oocytes in one or more rows.
  • Spicules paired, rose-thorn-shaped, not fused, rostrum usually prominent.
  • Male tail without caudal alae or gubernaculum; but with 3 pairs of ventrosubmedian papillae.
Spermatheca with sperm in outstretched female gonad.
The tail is mucronate (has terminal spikes) in some species.  
Males have no bursa and have rose-thorn-shaped spicules.


Body size range for the species of this genus in the database - Click:
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Economic Importance:

The genus Aphelenchoides contains species that feed on plants, fungi, and insects. The plant parasitic species have a very wide host range compared to many other types of plant-pathogenic nematodes (Kohl, 2011). Three globally distributed species: A. besseyi Christie, 1942, A. fragariae (Ritzema Bos, 1891) Christie, 1932 and A. ritzemabosi (Schwartz, 1911) Steiner & Buhrer, 1932, are economically important, causing losses in a range of agricultural and horticultural crops (Duncan & Moens, 2013).

Aphelenchoides besseyi, the rice white tip nematode, is an A-rated pest in California and is reported to parasitize more than 200 plant species (Cheng et al., 2013; Duncan & Moens, 2013), with rice, strawberry  and ornamental plants the most common hosts. A. besseyi is a major nematode pest in many Asian countries with yield losses in paddy rice ranging from 5.4 to 57.9% in Turkey (Tlek et al., 2014) and to 71% in China (Cheng et al., 2013; de Jesus et al., 2016).


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Plant-feeding and fungal-feeding, soil-inhabiting nematodes.

Nematodes of the genus Aphelenchoides can be recovered from soil, mosses, mushrooms, decaying organic materials or, in some cases, from plant tissues. Although most species of Aphelenchoides are fungivores, around 13 species are also known as plant parasites and crop losses due to some species are well documented.

Some species endoparasitic in leaves, but also feeds ectoparasitically on leaf and flower buds in some plants.

Many species of Aphelenchoides feed on fungi.  Fungal-feeding species are common in soil and generally appear to have shorter stylets (< 8 um) than plant-feeding species.

Ruess et al (2000) studied  the growth of Aphelenchoides sp. populations in vitro on 17 different fungal species.  Nematode populations developed on saprophytic (Agrocybe, Chaetomium) and especially on mycorrhizal fungi (Cenococcum, Hymenoscyphus, Laccaria).  They speculate that grazing by nematodes may influence the establishment and maintenance of mycorrhizal associations in the field. 

Mitosporic species, like Alternaria, Monocillium or Penicillium, were generally poor or non-hosts. This poor host status may be due to the release of toxic metabolites (e.g., antibiotics) and/or to morphological differences (e.g., forming of conidiophores) by the fungi. 

Food preference of Aphelenchoides sp. was tested in choice chamber experiments. Nematodes showed a marked preference for particular fungal species. They changed food source with time, indicating a "mixed diet" selection.  The attractiveness of a fungus was not necessarily correlated with its suitability as a host. 

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The genus Aphelenchoides has a wide host-range; plant-feeders usually associated with leaves and buds but most species are fungal feeders.

For an extensive host range list for this genus, click
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Life Cycle:

For Ecophysiological Parameters for this genus, click 
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Aphelenchoides - leaf damage video

Video Source: J.D. Eisenback, Nemapix.

Aphelenchoides sp. damage to leaves of Hosta 
Department of Plant Pathology Archive, North Carolina State University, Bugwood.org
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Allen, M.W. 1952.  Taxonomic status of the bud and leaf nematodes related to Aphelenchoides fragariae (Ritzema Bos, 1891).  Proc. Helminth. Soc. Wash., 19:108-120.

Aliramaji, F., Pourjam, E., Alvarez-Ortega, S., Afshar, F.J., Pedram, M. 2018. Description of Aphelenchoides giblindavisi n. sp. (Nematoda: Aphelenchoididae), and Proposal for a New Combination. J. Nematology 50:437-452. DOI: 10.21307/jofnem-2018-035.

Cheng, X., Xiang, Y., Xie, H., Xu, C.-L., Xie, T.-F., Zhang, C. & Li, Y. (2013). Molecular characterization and functions of fatty acid and retinoid binding protein gene (Ab-far-1) in Aphelenchoides besseyi. PLoS ONE 8, e66011.

de Jesus, D.S., Gonsalves Oliveira, C.M., Roberts, D., Blok, V., Neilson, R.,  Prior, T., Balbino, H.M., MacKenzie, K.M. D�Arc de Lima Oliveira, R. 2016. Morphological and molecular characterisation of Aphelenchoides besseyi and A. fujianensis (Nematoda: Aphelenchoididae) from rice and forage grass seeds in Brazil. Nematology 18:337�356.

Duncan, L.W. & Moens, M. (2013). Migratory endoparasitic nematodes. In: Perry, R.N. & Moens, M. (Eds). Plant nematology. Wallingford, UK, CABI Publishing, pp. 144-178.

Esmaeili, M. Heydari, R., Tahmoures, M. Ye, W. 2017. Aphelenchoides salixae n. sp. (Nematoda: Aphelenchoididae) isolated from Salix alba in western Iran. Nematology 19:697-707.

Golhasan, B., Ramin Heydari, Sergio Alvarez-Ortega, Mehrab Esmaeili, Pablo Castillo and Juan E. Palomares-Rius  2016. Aphelenchoides iranicus n. sp. (Nematoda: Aphelenchoididae) from West Azerbaijan province, Iran. Nematology 18:973-985.

Kohl, L. M. 2011. Foliar nematodes: A summary of biology and control with a compilation of host range. Online. Plant Health Progress doi:10.1094/PHP-2011-1129-01-RV

Mobasseri, M., E. Pourjam and M. Pedram. 2018. Morphological and molecular characterisation of Aphelenchoides primadentus n. sp. (Nematoda: Aphelenchoididae) from northern Iran .Morphological and molecular characterisation of Aphelenchoides primadentus n. sp. (Nematoda: Aphelenchoididae) from northern Iran. Nematology 20:97-109.

Nickle, W.R. 1970. A Taxonomic Review of the Genera of the Aphelenchoidea (Fuchs, 1937) Thorne, 1949 (Nematoda: Tylenchida) . J. Nematology 2:375-392.

Ruess, L., E.J. Garcia Zapata, J. Dighton. 2000. Food preferences of a fungal-feeding Aphelenchoides species.  Nematology 2:223-230.

Sanwal 1961 (Canadian J. Zool. 39:  143-148).

Scheck, H.J. 2021. California Pest Rating Proposal for Aphelenchoides fragariae (Ritzema - Bos, 1891) Christie, 1932 Strawberry crimp nematode, Strawberry spring dwarf nematode, Foliar nematode CDFA, Sacramento.

Tlek, A., Ates, S.S., Akin, K., Surek, H., Kaya, R. & Kepenekci, I. (2014). Determining yield losses in rice cultivars resulting from rice white tip nematode Aphelenchoides besseyi in field condition. Pakistan Journal of Nematology 32, 149-154.

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Copyright 1999 by Howard Ferris.
Revised: February 17, 2024