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).
The genus Aphelenchoides has as type species A. kuehnei
Fischer, 1894. Species of the genus occur in soil, decaying plant
residues, moss, and on the surfaces of rocks and trees. 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).
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
2. Length of post-uterine branch 5 or more times body width...3
Length of post-uterine branch less than 4 times
3. Tail bluntly rounded, with a single ventral spine.....A. subtenuis.
Tail terminus peg-like, with 4 small mucrons........A. ritzemabosi.
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.
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).
Ref: Nickle, 1970
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,
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).
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
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.
The genus Aphelenchoides has a wide host-range; plant-feeders usually associated with leaves and
buds but most species are fungal feeders.
Video Source: J.D. Eisenback, Nemapix.
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
de Jesus, D.S., Gonsalves Oliveira, C.M., Roberts, D., Blok, V.,
Neilson, R., Prior, T., Balbino, H.M., MacKenzie, K.M. Dï¿½Arc
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
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
Pourjam and M.
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
Nickle, W.R. 1970. A Taxonomic Review of the Genera of
the Aphelenchoidea (Fuchs, 1937) Thorne, 1949 (Nematoda: Tylenchida) . J.
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.
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
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