Hoplolaimus seinhorsti

 

Contents

  

Rev 07/17/2023

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

        Tylenchina
        Tylenchoidea
         Hoplolaimidae
          Hoplolaiminae

           Hoplolaimus seinhorsti Luc, 1958

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Morphology and Anatomy:

 

Female:  Length 1.0-1.48 mm.

  • Body cylindrical, slightly tapering towards front end; curved ventrally into an open circle when relaxed by gradual heating.  

  • Cuticle distinctly striated; annules almost 2 µm wide at midbody; subcuticular striation prominent, 2 striae for each annule.  

  • Lip region hemispherical, set off from body by a deep constriction, usually with 4 annules; as many as 6 annules may be present.  Basal annule of lip region with 8 to 12 longitudinal striations.  

  • Labial framework well-developed and sclerotized, displaying a yellow color, outer margins extending backward for a distance of 3.5 annules.  

  • Lateral fields reduced, represented by a single incisure on body, but often indistinct.  

  • Phasmids large, 4 or 5 µm in diameter, very refractive, anterior one at 26 to 44%, posterior one at 74 to 90% of body length from anterior end; anterior and posterior phasmid may be situated on either side of body.  

  • Excretory pore 109 to 145 µm from anterior end of body, usually opposite level of nerve ring or isthmus.

  • Hemizonid 7 µm long, situated 5 to 21 annules posterior to excretory pore.

  • Hemizonion 5 to 10 annules posterior to hemizonid; hemizonid and hemizonion often appear as double structures at different levels in the body.  

  • Stylet massive, well-developed, 40 to 49 um long, composed of two almost equal parts with large basal knobs; spear knobs with two blunt points on anterior margin separated by 2 or 3 small teeth, the latter often indistinct.  

  • Orifice of dorsal esophageal gland 4 or 5 µm behind spear base.  

  • Esophagus typical of the genus; median bulb oval, occupying about half of the body diameter, situated at 44 to 50% of the esophageal length.

  • Dorsal esophageal gland with 4 nuclei, overlaps the intestine dorsally; the 2 uni-nucleate subventral glands lie dorsolaterally and are variable in length; total of 6 nuclei in the three glands  

  • Intestine does not overlap rectum.  

  • Vulva at midbody or slightly posterior.  Epiptygma usually single, anterior or posterior, but sometimes double. 

  • Gonads paired, opposed and outstretched; no spermatheca observed.  

Tail shorter than anal body diameter, rounded, with 10 to 17 annules; striations encircling the tip are sometimes irregular.

Male: Unknown.


[Ref: CIH Descriptions of Plant-parasitic Nematodes, Set 6, No. 76 (1976)]
 

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

 
 
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Distribution:

Africa, India, Philippines, Thailand, and Indonesia.

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Economic Importance:

 

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Feeding:

 On cowpea, H. seinhorsti was found to be endoparasitic, mainly in the parenchymatous tissue of the root cortex and also in the cortex of root nodules.  

In cotton roots, it was also found to be completely inside the cortical parenchyma (Luc, 1958).

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Hosts:

Cotton, sugarcane, cowpea, sorghum, rice, corn, melon, many types of vegetables, coconut, and banana.

For an extensive host range list for this species, click

 


 
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Life Cycle:

Ecophysiological Parameters:

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

Seeds of cowpea were germinated in a field plot in Nigeria naturally infested with H. seinhorsti.  One week after germination, the roots contained all larval stages as well as eggs.  Most nematodes were in the parenchymatous tissue of the root cortex, and browning of cells was evident immediately around individual nematodes.  

The nematodes increased in the roots to a maximum of 1,110 individuals/root system after 5 weeks. 

In the soil, the population increased from 100 to 3,800 individuals/liter of soil after 9 weeks (Bridge, 1973).    

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Damage:

Endoparasitic migrations of nematodes can cause considerable mechanical damage to root cells.  

Nematodes are mainly confined to lateral roots, and by the end of 9 weeks following germination of cowpea in field plot experiments, most lateral feeder roots were necrotic or missing.

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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:

CIH Descriptions of Plant-parasitic Nematodes, Set 6, No. 76 (1976)

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Copyright © 1999 by Howard Ferris.
Revised: July 17, 2023.