Tylenchorhynchus annulatus

 

Contents

  

Rev 04/03/2021

Stunt Nematode  Classification Hosts
Morphology and Anatomy Life Cycle
Return to Tylenchorhynchus Menu Economic Importance Damage
Distribution Management
Return to Telotylenchidae Menu Feeding  References
    Go to Nemaplex Main Menu   Go to Dictionary of Terminology

 

 

Classification:

     

Rhabditida
       Tylenchina
        Tylenchoidea
           Telotylenchidae
             Telotylenchinae

Tylenchorhynchus annulatus (Cassidy, 1930) Golden, 1971 

    Synonyms:
      Tylopharynx annulatus Cassidy, 1930
      Anguillulina annulata (Cassidy, 1930) Goodey, 1932
      Chitinotylenchus annulatus (Cassidy, 1930) Filipjev, 1936
     Tylenchorhynchus martini Fielding, 1956

Back to Top

Morphology and Anatomy:

Length, female: 0.66-0.72 mm long.  T. annulatus = (T. martini)

Female: Body ventrally arcuate; cuticle moderately thick, distinctly annulated by deep striae 1.7-1.9 µm apart near midbody; no longitudinal striae.

Lateral fields 0.30-0.35 times body width, with 4 incisures making  3 almost equally wide longitudinal bands; outer incisures crenate; outer bands irregularly areolated in places. 

Deirids absent.

Phasmids distinct,  pore-like, 13-17 µm or 7-8 annules behind anus, anterior to middle of tail. 

Lip region rounded, slightly marked off from body by increased width, with 3 transverse striae (occasionally 2); 7.0-7.5 µm wide and 4 µm high; framework lightly sclerotized with outer margins extending 2 to 3 annules into body. 

Stylet is 17-18 µm long, in two almost equal parts, anterior conical part solid, needle-like in distal half, posterior part with distinct, rounded basal knobs, about 3 µm across and with flattened to convex anterior surfaces. 

Orifice of dorsal esophageal gland 1.5-2 µm from stylet base, rather obscure. 

Median esophageal bulb oval, occupying 6 to 7 body annules, with oval valve near center. 

Basal esophageal bulb sac-like, with a large cardia pushing into its base slightly ventrally; nucleus of dorsal gland conspicuous, in posterior half of bulb; nuclei of subventral glands inconspicuous, about middle of bulb.

Nerve ring at middle of isthmus. 

Excretory pore 52-59 annules behind lip region, opposite base of isthmus. 

Hemizonid prominent, 2 body annules long, just in front of excretory pore. 

Intestine with fasciculi (serpentine canals) and scattered granules.

Rectum shorter than anal body width, partially overlapped by intestine; anus distinct. 

Tail elongate sub-cylindrical, 3.1-3.6 times anal body width long, almost straight to slightly arcuate ventrally, with 18-22 annules ventrally and a broadly round, unstriated terminus. 

Vulva transverse; vagina straight, extending half-way into body. 

Spermatheca absent. 

Ovaries paired, outstretched, opposed, with a single row of oocytes.

Male: absent.  Not found among 80,000 specimens examined by Fielding  (1956).

[Ref: CIH Descriptions of Plant-parasitic Nematodes, Set 6, No. 85 (1976)]



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

Distribution:

Tropical and subtropical areas; e.g., India, parts of Africa, Venezuela, Hawaii, Louisiana, Texas, Florida, and Georgia.

 

Back to Top

Economic Importance:

 

 

Back to Top

Feeding:

Migratory ectoparasite.

Back to Top

Hosts:

Sugarcane, rice, sorghum, sweet potato, soybeans, red clover, cotton, ornamentals, and grasses.  Potato is a less-favorable host.

For an extensive host range list for this species, click


Back to Top

Life Cycle:

Ecophysiological Parameters:

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

On oat and wheat seedlings, T. annulatus multiplies more rapidly at higher soil temperatures (30 C) than at lower temperatures (18 and 24 C).

Nematodes are capable of withstanding a wide variation of soil temperature extremes. 

Soil-type has no apparent influence on population growth.

Swarming: The phenomenon of swarming was reported by Hollis (1958); swarming has also been observed in other nematodes, e.g., Rotylenchulus,  Hemicycliophora, Aphelenchus, Heterorhabditis, especially in drying conditions.  Hollis felt swarming was initiated by rapid growth of host plant and nematodes kept together by stickiness of outer cuticle. 

Stickiness and swarming are inhibited by pectidase enzymes.  If food is less available, nematodes revert to a non-swarming state. 

Hollis considered swarming a virus disease, and claimed virus particles might be infecting somatic muscles and hypodermis, but this has not been confirmed.

No other virus diseases of nematodes are known.
    

Back to Top

Damage:

Nematode is pathogenic to sugarcane in Louisiana; in studies, inoculated plants had more sparse, irregular, and stubby roots than the control. 

Hollis et al. (1959) and Hollis (1967) concluded that, although slight reduction of growth of rice seedlings was demonstrated with high population levels, this nematode was not pathogenic to rice. 

Other researchers have observed that both swarming and non-swarming nematodes of this species can cause significant reductions in root length and root dry  weights of the rice cultivars Saturn and Zenith, but swarmers accounted for a greater reduction than the non-swarmers, and caused severe stunting and chlorosis of the plants (Joshi & Hollis, 1976). 

Johnson (1970) reports that this species feeds on roots of Bermuda grass (Cynodon dactylon) ectoparasitically, usually on the young, succulent roots.  The root damage results from feeding involving cell destruction, injection of digestive secretions, and removal of cellular contents; feeding on lateral roots results in root-pruning, decreased water and mineral uptake, and depressed plant growth; feeding on root-tips causes severe stunting and  necrosis.

 [Ref: CIH Descriptions of Plant-parasitic Nematodes, Set 6, No. 85 (1976)]

Back to Top

Management:

Soil fumigation for rice and sugarcane recommended in Texas and Louisiana.
Most sugarcane varieties used in breeding programs show very little or no resistance to infection by T. annulatus.  Control of weed hosts is  important, e.g., Johnson grass. 

No satisfactory crop rotation management strategies exist (but rotation to rice may be effective in preventing damage to sugarcane in Louisiana).

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

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

 

 

Back to Top

References:

 

Back to Top
Copyright © 1999 by Howard Ferris.
Revised: April 03, 2021.