Aphelenchoides

 

Contents

 

Rev 12/27/2013

 Foliar Nematodes Classification Hosts
Morphology and Anatomy Life Cycle
Return to Aphelenchoides Menu Economic Importance Damage
Distribution Management
Return to Aphelenchoididae Menu Feeding  References
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Classification:

     
Chromadorea
       Rhabditida
          Tylenchina
            Aphelenchoidea
             Aphelenchoididae
           Aphelenchoidinae
            Aphelenchoides

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 are more species described now.

 
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Morphology and Anatomy:


Nematode is 0.5-1.2mm long, and slender.  

  • Nematodes in this genus have a large metacorpus.
  • Dorsal overlap of the esophageal glands over the intestine. 
  • They have a 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.

  

 
 
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.

 

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Distribution:

 

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Economic Importance:

 

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Feeding:

Endoparasite 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 m) 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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Hosts:

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

For an extensive list of host plant species and their susceptibility to this genus, copy the genus name

Aphelenchoides

select Nemabase Genus Search and paste the name in the Genus box

 

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Life Cycle:

 
 
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Damage:

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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Management:

 

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References:

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.

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)

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For more information about nematodes, Go to Nemaplex Home Page.
Copyright 1999 by Howard Ferris.
Revised: December 27, 2013