Helicotylenchus multicinctus

 

Contents

 

Rev 04/11/2018

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

        Tylenchina
        Tylenchoidea
         Hoplolaimidae

  Helicotylenchus multicinctus (Cobb, 1893) Golden, 1956 

  Synonyms:

      Tylenchus multicinctus Cobb, 1893
      Tylenchorhynchus multicinctus (Cobb) Micoletzky, 1922
      Anguillulina multicincta (Cobb) Goodey, 1932
      Rotylenchus multicinctus (Cobb) Filipjev, 1936
      Rotylenchus iperoiguensis Carvalho, 1956
      Helicotylenchus iperoiguensis (Carvalho) Andrassy, 1958


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Morphology and Anatomy:


A,B,C = "spiral" configuration of relaxed adults; G,H = male tails; I,J = female tails

Female:

  • Length, female: 0.47-0.53 mm
  • Body arcuate to c-shaped when relaxed; annules distinct, about 1.5 µm wide at midbody.
  • Lateral fields not areolated, with 4 incisures, about one-fourth of body width. 
  • Lip region hemispherical, slightly offset, with 3-5 (usually 4) annules and a prominent oral depression terminally; framework heavily sclerotized, with conspicuous outer margins extending posteriorly through 3 to 4 body annules, which are much narrower at that region than at others.
  • Anterior and posterior cephalids usually indistinct, 0 to 1 and 4 to 6 annules posterior to cephalic framework, respectively. 
  • Stylet guiding tube prominent, bulbous.  Stylet well developed, 21-24 µm long, with prominent basal knobs measuring 5-6 µm across, and having outer margins directed forward, resulting in anterior surfaces appearing flattened or concave. 
  • Procorpus usually expanded anteriorly.
  • Median esophageal bulb round to oval with small valve in center; about 6 body annules long.
  • Esophageal glands compact, wrapped around front end of intestine; dorsal glands anterior to subventrals. 
  • Excretory pore level with or close to esophago-intestinal junction.
  • Hemizonid usually distinct, 2-3 annules long, 0-3 annules anterior to excretory pore
  • Hemizonion minute, 6-8 annules behind excretory pore. 
  • Ovaries paired, symmetrical, but sometimes the posterior one is reduced. 
  • Spermathecae slightly offset, rounded, usually filled with sperms. 
  • Vulva prominent, a depressed transverse slit. 
  • Intestine not overlapping rectum.
  • Tail slightly tapering, with a hemispherical annulated terminus, usually with greater curvature dorsally than ventrally, devoid of any ventral projection or mucro, with 6-13 annules.
  • Inner incisures of lateral fields usually not fusing for some distance on tail. 
  • Phasmids pore-like, 1-6 annules anterior to anus level.


 

 

Male:

  • length, male: 0.43-0.55 mm (0.48 mm av.).
  • Similar to female, except for sexual dimorphism
  • Abundant. 
  • Testis single, anteriorly outstretched; sperms small, rounded. 
  • Bursa short, not conspicuously projecting beyond body contour in lateral view, crenate and enclosing tail. 

  • Spicules only slightly cephalated with narrowed distal half bearing small ventral flanges.
  • Gubernaculum simple.

[Ref: CIH Descriptions of Plant-parasitic Nematodes, Set 2, No. 23 (1973)]

 

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

 
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Distribution:

World-wide on banana; all banana plantations in Israel are said to be infested. In South Africa, the nematode is regarded as a common pest on the roots of banana and pineapple.

The absence of H. multicinctus from semi-arid tropics of West Africa has been ascribed to the adverse effects of high soil temperature on multiplication rate and low survival rate after soil desiccation during the dry season (Baujard and Martiny, 1995).
 

 

 

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Economic Importance:

A major pest of bananas.

Nematode is a major pest of banana in Israel, Ivory Coast and caneroon in west  Africa, and all of Central America.

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Feeding:

Ecto- and semi-endoparasite in outer cortex. 

Blake (1966) observed that within 36 hours of inoculation of banana roots, some adult nematodes were partly embedded in the roots and apparently feeding upon the parenchymatous cells; after 4 days, they were completely buried within the cortex, sometimes to a depth of 4 to 6 cells.  The cells in the vicinity of the nematode head had distorted and ruptured walls, contracted cytoplasm, and enlarged nuclei.  Such cells, as well as those associated with the eggs, were often discolored and/or necrotic.

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Hosts:

Banana, cocoa, sugarcane, coffee, corn, tea, and others. 

F

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

The species is bisexual and reproduces by cross-fertilization or amphimixis

The nematodes easily get introduced into virgin land with banana soil and rhizomes, usually brought from old, infested plantations.

The nematodes can survive 4 months without host plants, but is less resistant to desiccation than H. dihystera (Baujard and Martin, 1995). 

All stages of the nematode may be found within roots and, perhaps, the entire life cycle is completed there, but there is no evidence of nematode migration through the cortex. 

Groups of 8-26 eggs were observed in discolored cortical tissues; 48-51 hours were needed for the newly laid eggs to hatch in tapwater at 30 C, and the first molt is believed to take place outside the eggs shortly after hatching. 

The second stage juveniles are recognized by their ventral digitate tail process. 

The female gonad primordium is 2- and 6-celled in the early third-stage juveniles and at the third molt, respectively.  During the fourth molt, the male and female gonads complete their development, and the vulva and vagina are seen in females still within the fourth stage larval cuticle (Zuckerman & Strich-Harari, 1964).

[Ref: CIH Descriptions of Plant-parasitic Nematodes, Set 2, No. 23 (1973)]    

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Damage:

Nematode produces necrotic lesions on roots. 

Yield of infested banana plants declines to an unacceptable level after three years.  Components of loss include toppling, reduced fruit size and variability, delayed maturity, missed markets (ref Queneherve).

 

 

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Management:

Banana rhizomes can be peeled and dipped in water for 20 min at 55 C or, in the past, were dipped in DBCP solution. 

"Flood fallowing" has been used in Surinam to rehabilitate old (infected) banana plantations. 

Injection of DBCP into the soil as a 1:3 water solution at a depth of 20 cm in two circles, 15 and 50 cm from the pseudostems of banana plants was effective.  When used as a drench with irrigation water, DBCP gave good control when the soil did not contain a large proportion of heavy clay.

Paring and pralinage in India.  Cut off diseased tissue and coat rhizome with nematicide-soaked mud (e.g., furadan) for a few days before planting  (note: pralines are chocolate-coated candies).

Modern techniques of micro-propagation in tissue culture in industrial banana production systems provide nematode-free plantlets for plantation establishment.

Tactics for Banana: 

Lesions on pared banana rhizome
Peeled banana corms soaking in nematicide solution for control of migratory endoparasitic nematodes.
Tissue culture production system for producing nematode-free banana plants (Photograph by Luis Pocasangre)

A healthy plantation may remain productive for up to 20 years; an infested one for only 2 or 3 years. Thus, there is considerable economic benefit to 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:

 Baujard, P. and B. Martiny.  1995.  Ecology and pathogenicity of the Hoplolaimidae (Nemata) from the sahelian zone of West Africa: 7. Helicotylenchus dihystera (Cobb, 1893) Sher, 1961 and comparison with Helicotylenchus multicinctus (Cobb, 1893) Golden, 1956. Fundamental and Applied Nematology 18: 503-511.

CIH Descriptions of Plant-parasitic Nematodes, Set 2, No. 23 (1973)

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Copyright © 1999 by Howard Ferris.
Revised: April 11, 2018.