Ditylenchus paraoncogenus

 

Contents

 

Rev 09/23/2023

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

      Tylenchida
       Tylenchina
        Tylenchoidea
         Anguinidae
          Anguininae
          
 Ditylenchus paraoncogenus Hashemi, Karegar, Helder, Holterman & Hesar, 2022

 

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Morphology and Anatomy:

 

 

   Males:

  • Generally similar to female but with narrower body. Cuticular annulation hardly seen.
  • Procorpus less thick than in females,
  • Monorchic, testis outstretched, sometimes reaching close to basal pharyngeal bulb, spermatocytes in two rows.
  • Spicules ventrally arcuate, with minute processes at the base of  manubrium and anteriorly pointed cuticle parts within the lamina.
  •  Gubernaculum simple and crescent-shaped.
  • Bursa enveloping 63.2% (33.3-74.4%) of tail length.

Ref: Hashemi et al., 2022

Reported median body size for this species (Length mm; width micrometers; weight micrograms) - Click:


 

Females:

  • Body vermiform, greater diamter in individuals from plant tissues than from soil.
  •  Cuticle finely annulated. Lateral fields narrow, occupying 7.6-20.5% of body width; usually with six incisures.
  •  Head with two or three fine annuli, not offset.
  • Cephalic skeleton moderately developed.
  • Stylet well developed for the genus, conus 31.1-54.3% of its length, knobs distinct and rounded.
  • DEGO 0.7-1.8 um posterior to the stylet knobs.
  • Procorpus wide; median bulb oval and muscular, with distinct valve, isthmus cylindrical, more slender and rather shorter than the procorpus. Nerve ring surrounding isthmus.
  •  Hemizonid about 2-4 cuticular annuli long, in the vicinity of secretory-excretory pore (S-E). Deirids at level of S-E pore.
  • Basal pharyngeal bulb usually elongate and cylindrical to pyriform, offset from intestine or with slight overlap over intestine
  • Monodelphic-prodelphic, ovary outstretched and sometimes reaching median pharyngeal bul.
  •  Spermatheca elongated and filled with large and rounded sperms. Uterus quadricolumellar.
  • Vagina 21.7-47.1% of vulval body width (VBW).
  • Post-vulval uterine sac (PUS) 3.2 (2.3-5.6) times VBW,
  •  Tail thick conical, narrowing gradually after anus or abruptly before the end, with variable terminus, usually pointed, sometimes rounded; seldom mucronate.
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Distribution:

Described from galls on the aerial parts of tumble thistle (Gundelia tournefortii L.) in Fars Province, Iran (Hashemi et al., 2022).

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Economic Importance:

 

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Feeding:

 Feeding as an enodpsrasite on aboveground parts of Gundelia and Cirsium. The nematodes did not feed on fungal cultures of Rhizoctonia solani or Fusarium oxysporum (??)

Feeding on Gundelia tournefortii causes swelling, galling and deformation of stems, leaves and flowers.  Galls on stem are rather elongated.  Two types of galls are seen on leaves, green and smooth galls without thorns  and white to light green galls with thorns, which can also be seen on flowers.

Large numbers of eggs, juveniles and adults can be extracted from fresh galls (Hashemi et al., 2022).

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Hosts:

Tumble thistle (Gundelia) and Cirsium vulgare.  Hashemi et al; (2022) indicate that potato is not a host.
 

For an extensive host range list for this species, click

 

ITS and 18S rDNA sequences of 17 populations of Ditylenchus showed a close relationship between D. paraoncogenus  and the stem nematodes D. oncogenus, D. gigas, D. weischeri and D. dipsaci
 
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Life Cycle:

Sexually reproducing based on abundance of males and presence of sperm in spermatheca.

Ecophysiological Parameters:

For Ecophysiological Parameters for this species, click If species level data are not available, click for genus level parameters

Althouh fungi apparently dop not serve as alternate hosts, D. paraoncogenus survive d in anhydropiotic state in tumble thistle galls and ws viable after four years (Hashemi et al., 2022).

     

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Damage:

 

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Management:

Host Plant Resistance, Non-hosts and Crop Rotation alternatives:

For plants reported to have some level of resistance to this species, click

 

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References:

Hashemi, K., Karegar, A., Helder, J., Holterman, M., Hesar, A.M. 2022. Characterisation of Ditylenchus paraoncogenus n. sp. (Nematoda:Anguinidae), a new stem nematode parasitising tumble thistle. Nematology 24:791-808.

 

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Copyright 1999 by Howard Ferris.
Revised: September 23, 2023.