Rotylenchus robustus

 

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Rev 10/06/2008

  Classification Hosts
Morphology and Anatomy Life Cycle
Return to Rotylenchus Menu Economic Importance Damage
Distribution Management
Return to Hoplolaimidae Menu Feeding  References
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Classification:

      Tylenchida
       Tylenchina
        Tylenchoidea
         Hoplolaimidae
          Hoplolaiminae
           Rotylenchus robustus (de Man, 1876) Filip'ev, 1936

       Synonyms:
      Tylenchus robustus de Man, 1987
      Hoplolaimus uniformis Thorne, 1949
      Rotylenchus uniformis (Thorne, 1949) Loof & Oostenbrink, 1958
      Anguillulina robusta Goodey, 1932
      Rotylenchus goodeyi Loof & Oostenbrink, 1958
      Rotylenchus fallorobustus Sher, 1965

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Morphology and Anatomy:

Female: 

  • Length of female = 1.2-1.8 mm.

  • Upon relaxation, female body usually forms a single spiral, sometimes C-shaped.

  • Cuticular striations prominent.  

  • Lateral fields irregularly areolated on mid-body, with 4 incisures.

(Photomicrograph, I.A. Zasada).  

  • Lip region hemispherical, offset by a constriction, with 6-7 distinct annules and a terminal disc; lip annules longitudinally indented to give a tiled surface appearance.  

  • Anterior and posterior cephalids distinct.

  • Spear well developed, usually about 46 µm long; anterior tapering portion 50-56% of its total length; basal knobs large, rounded, but sometimes with flat or indented anterior surfaces.  

  • Median esophageal bulb ovate, very muscular and with a prominent valve in center.  

  • Esophageal glands extending over intestine dorsally and dorso-laterally as the two subventrals are shifted from their normal to subdorsal position.  Nuclei of subventral glands varying in position from slightly posterior to slightly anterior of dorsal gland.  

  • Excretory pore usually close to esphago-intestinal valve, just behind the hemizonid which is distinct and 3 annules long. 

  • Hemizonion indistinct.  

  • Vulva a depressed, transverse slit, epiptygma short, double but sometimes appearing single in lateral view.  

  • Two branches of gonad outstretched in opposite directions.

  • Spermathecae rounded, usually packed with sperms.

  • Ovaries with a single row of oocytes except for a few in germinal zone.  

  • Intestine partially overlapping rectum.  

  • Tail hemispherical, regularly annulated, with 8-17 annules from anus to center of terminus.  

  • Phasmids distinct, pore-like, usually just preanal but varying from 3 annules posterior to 7 annules anterior to anal level.

Male:

  • Body length 1.0-1.3 mm.

  • Body in open C shape when relaxed.  

  • Lip region more distinctly offset and elevated than in female. 

  • Bursa crenate, enveloping tail. 

  • Spicules slightly cephalated and ventrally arcuate, with well developed ventral flanges on distal third.  

  • Gubernaculum protrusible, with prominent titillae distally.  Capitulum (=telamon) 9-12 µm long.  

  • Testis single, outstretched.

[Ref: CIH Descriptions, Set 1, No. 11 (1972)]
 

 

 
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Distribution:

Europe and the U.S.  Occurs in soils around Davis and at Half Moon Bay.     

In Britain, is reported from R. robustus a wide range of soil types but preferred more moist, alkaline soils and had a broader ecological amplitude than other species  (Boag and Neilson, 1996).
           

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Economic Importance:

 

 

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Feeding:

Ectoparasitic.

 

 

Photomicrograph by U. Zunke

 

 

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Hosts:

Trees, meadows, grasses, and vegetables.

Bog myrtle, oak and hawthorn in Britain (Boag and Neilson, 1996).

 

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Life Cycle:

The nematode prefers sandy soils; survives in fallow soil for up to 6 months, with mortality usually not exceeding 50%.  

A temperature of 13C  is unfavorable for survival, but temperatures of 18.5 C and 24 C are equally favorable for development.  The first molt occurs within the eggs, and the second-stage juvenile hatches after 14 to 16 days.  The second generation appears only after about 100 days, at about 23 C; half of this time is taken up by the fourth larval stage.  

Male and female juveniles are recognizable after the third molt by light areas in the region of the developing gonad and also by their body lengths.

[Ref: CIH Descriptions Set 1, No. 11 (1972)]
    

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Damage:


In the Netherlands, nematode stunts peas and causes root-rot; also causes damage which affects shape and size of carrots.  

In California, nematode causes stunting and yield reduction in lettuce (Lear et al., 1969).

In the presence of Fusarium oxysporum, nematode feeding can cause extensive decay of the root cortex of peas, which consequently show "early yellowing".  Symptoms are 3.5 times more severe with nematode/fungus association than with fungus or nematode alone (Labruyere et al., 1959).
 

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Management:

Nematicides:

1,3-Dichloropropene (1,3-D) and ethylene dibromide (EDB) preplant treatment reduced damage in lettuce (Lear et al., 1969).  

Crop Rotation:

Rotation to potatoes recommended in the Netherlands to improve carrot yield.

 

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References:

Boag, B.and R. Neilson.  1996.  Distribution and ecology of Rotylenchus and Pararotylenchus (Nematoda: Hoplolaimidae) in Great Britain. Nematologica 42: 96-108.

CIH Descriptions of Plant-parasitic Nematodes, Set 1, No. 11 (1972)

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Copyright © 1999 by Howard Ferris.
Revised: October 06, 2008.