Cacopaurus pestis




Rev 02/13/2023

Persian Sessile Nematode Classification Hosts
Morphology and Anatomy Life Cycle
Return to Cacopaurus Menu Economic Importance Damage
Distribution Management
Return to Tylenchulidae Menu Feeding  References
    Go to Nemaplex Main Menu   Go to Dictionary of Terminology



Cacopaurus pestis Thorne, 1943

Cacopaurus pestis is the type and only species of the genus


Paratylenchus pestis (Thorne, 1941) Goodey, 1963.

Back to Top

Morphology and Anatomy:

Length, female: 0.20-0.30 mm; length, male: 0.24-0.30 mm.

Female: body cylindrical, obese, about 1/7 as broad as long, often more or less sharply bent, with broad conical terminus and blunt anterior end. 

Cuticle with annules about 1 µm wide at midbody and ornamented with minute refractive tubercles. 

Head smooth with minute lip region and obscure cephalic framework;.

Excretory pore in region of median esophageal bulb.

Lateral field divided into 3 bands by 4 longitudinal incisures resembling rows of dots; field broadening near vulva to enclose a scutellum-like area, then narrowing and continuing to terminus. 

Vulva broad, posterior, without flaps, body narrows behind it; anus obscure, subterminal. 

Spear long, curved, approximately 97 µm long; the anterior part about 6 times as long as the posterior part, which has rounded knobs.  Female attached the host root by the deeply embedded, slender spear which is often broken when the nematode becomes detached. 

Esophagus with procorpus hardly offset from metacorpus, which is has a well-developed valve apparatus;  clearly delimited, narrow isthmus encircled by nerve-ring; swollen posterior part of esophagus forming a small bulb abutting on intestine, the cells of which are filled with fat globules. 

Ovary single, with 2 flexures, reaching anteriorly well beyond the spear base; oviduct made up of a few large cells, one becoming a spermatheca; uterus forming a conspicuous, thick-walled chamber; vagina short, directed forward.  The uterine egg may be as long as 1/ 4 body length.


Males:  Reduced, with stylet reduced or absent, and probably do not feed. 

Body relatively slender; cuticle with fairly coarse, un-ornamented annules; lateral field with 3 or 4 faint longitudinal lines; deirids conspicuous, opposite anterior end of intestine (Thorne, 1943); rounded head lacking skeletal structure and spear; esophagus degenerate. 

Testis with small cap cell; spicules slender, curved, cephalated; thin, curved gubernaculum; small ad-anal bursa formed from cuticular flaps.

Juveniles: Second-stage juvenile with rounded head with light skeletal framework; spear slender, but well developed, with backwardly sloping knobs; esophagus moderately well developed, organized as in female; excretory pore at level of isthmus, which is encircled by nerve ring.  Tail elongate-conoid, with bluntly rounded tip.

      C. pestis is the only species in the genus and, in many respects, resembles some species of Paratylenchus.  It differs in the more obese form of the adult female, the ornamentation of the cuticle, the long spear and the shorter, more bluntly rounded post-vulval region of the body.  The male differs in the presence of the cuticular bursa; the larval stages differ in having well-developed stylets.

Ref: CIH Descriptions of Plant-parasitic Nematodes, Set 3, No. 44 (1974)


Powerpoint display of anatomical features - Cacopaurus pestis

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

Back to Top


California and France.


Back to Top

Economic Importance:

Back to Top


Sedentary once feeding starts; nematode adheres to roots; feeds from cortical and epidermal cells causing swelling and rupturing of the cells.


Back to Top


Walnut, citrus, and roses.

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


Meiotic divisions in germinal zoneds of gonad give rise to oocyter and spermatocytes with a haploid number of 5 to 6 chromosomes. Amphimictic pairing of males and females re-establiches the diploid number (Dalmasso et al., 1973).

Females deposit eggs at the feeding site; larvae begin to feed in the same area so that small colonies of nematodes are formed which comprise individuals of all stages. 

Juveniles occur in the soil in small numbers, suggesting that they remain free for only a short duration before permanently attaching themselves to feeding sites. 

Small numbers of males are also found free in the soil. 

More than 100 females/g root have been recovered from rose roots in France.  Reproduction is probably continuous.

Old females turn brown, and eventually, their empty cuticles may be found on and around roots in old infestations.


Back to Top


Roots affected by nematode feeding may be killed; large numbers of dead roots have been found on infected walnut trees.  Thorne (1943) reported severe damage and death to walnut trees infected with C. pestis, but frost and reduced rainfall may have aggravated the decline of the trees. 

No significant damage has been attributed to C. pestis on citrus or rose in France where the nematode is thought to be indigenous.

Back to Top


Thorne (1943) presented observational evidence that California black walnut (Juglans hindsii) is resistant to C. pestis.

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


Dalmaso, A., Macaron, J. and Berge, J.B. 1973. Modalities de la reproduction chex Tylenchulus semipenetrans et chez Cacopaurus pestis (Nematoda, Criconematoidea). Nematologica 18:423-431.

Ghaderi, R., Geraert, E., Karegar, A. 2016. TheTylenchulidae of the World. Academia Press, Ghent, Belgium

Thorne, G. 1943. Cacopaurus pestis n.g, n.sp. (Nematoda: Criconematoinae), a destructive parasite of the walnut Juglans regia Linn.  Proc. Helminth. Soc. Wash 10:78-83.

Back to Top/a>

For more information about nematodes, Go to Nemaplex Main Menu.
Copyright © 1999 by Howard Ferris.
Revised: February 13, 2023.