Cacopaurus pestis

Cacopaurus pestis	Contents	Rev 12/17/2024
Persian Sessile Nematode	Classification	Hosts
	Morphology and Anatomy	Life Cycle
Return to Cacopaurus Menu	Economic Importance	Damage
	Distribution	Management
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Classification:

Chromadorea Rhabditida Tylenchina
Tylenchuloidea

         Tylenchulidae
          Paratylenchinae

Cacopaurus pestis Thorne, 1943

Cacopaurus pestis is the type and only species of the genus

Synonyms:

Paratylenchus pestis (Thorne, 1941) Goodey, 1963.

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:

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Distribution:

California and France.

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Economic Importance:

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Feeding:

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

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Hosts:

Walnut, citrus, and roses.

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

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.

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Damage:

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.

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.