Rotylenchulus parvus

Rotylenchulus parvus	Contents	Rev 11/11/2024
	Classification	Hosts
	Morphology and Anatomy	Life Cycle
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	Distribution	Management
Return to Hoplolaimidae Menu	Feeding	References
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Classification:

        Tylenchina
        Tylenchoidea
         Hoplolaimidae
          Rotylenchulinae

Rotylenchulus parvus (Williams, 1960) Sher, 1961

Synonyms:

Helicotylenchus parvus Williams, 1960

Morphology and Anatomy:

Immature females;

When relaxed, in a C- shape to a loose spiral
Stylet slender with backward sloping knobs (12-15 um long)
DEGO about one stylet length from stylet base
Esophagus overlaps intestine laterally and ventrally.

Mature Female: Obese and twised into a kidney shape; irregulary swollen, widest at vulva; vulva on a protruberance

	Immature Female (left): Mature Female (below):

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

Distribution:

Originally described from sugarcane in Mauritius as Helicotylenchus parvus by Willimas (1960).

Widespread in eastern and southern Africa on several important crops

Reported by Konicek, 1963 on cotton in the Imperial Valley of Calkiforonia, where it is occasionally found.

A more complete list of reported distribution from Mitchell (2024) below:

Africa: Cote d'Ivoire, Egypt, Kenya, Malawi, Mauritius, Mozambique, Somalia, South Africa, Tanzania, Uganda, Zambia, Zimbabwe.

America: Dominican Republic, United States of America (Arizona, California, Florida), Virgin Islands (US).

Asia: India, Iran, Pakistan. Europe: Cyprus.

Oceania: Australia.

Economic Importance:

C-rated pest in California Nematode Pest Rating System.

Feeding:

Sedentary semi-endoparasite of plant roots.

Hosts:

Cotton but also reported on corn, potato, cowpea, sweetpotato and cassava (Martin, 2024).

For an extensive host range list for this species, click

Eggs, juvenile stages, immature females, and immature and mature males, occur in the rhizosphere soils of host plants. The genus is bisexual and can reproduce through cross-fertilization and through parthenogenesis with females alone.

Males of R. parvus are quite rare and, in greenhouse studies, the life cycle (egg to egg) was completed parthenogenetically in 27-36 days without the presence of males.

Juvenile stages apparently do not feed and undergo three molts to becom immature females.. Soon after the final molt, the vermiform immature adult female becomes infective and penetrates host roots with the anterior part of the body, the posterior part remaining outside the root. Feeding incites hypertrophy and nurse cell formation in the pericycle and endodermis. Destruction of epidermal and cortical cells during pebnetration and establishment of the feeding site results in browning and necrosis of surrounding tissue. About one week after root penetration, the immature female body on the root surface enlarges to a typical kidney shape. The female secretes a gelatinous matrix that encases her body on the surface of the root and eggs are deposited (75-100) within the matrix (Dasgupta and Raski, 1968; Jatala, 2020; Mitchell, 2024).

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

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Damage:

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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:

Dasgupta, D.R. and Raski, D.J. The biology of Rotylenchulus parvus.s Nematologica 14:429-440

Heyns, J. 1976. CIH Desaiptions of Plant-parasitic Nemaodes #83

Jatala, P., 2020. Reniform and false root-knot nematodes, Rotylenchulus and Nacobbus spp. In Manual of Agricultural Nmatology (pp. 509-528). CRC Press.

Konicek, D.E., 1963. A plant-parasitic nematode of the genus Rotylenchulus found in California. Phytopathology, 13:1140

Martin, H.J. 2024. California Pest Rating Proposal for Rotylenchulus parvus (Williams) Sher, 1961. California Department of Food and Agriculture, Sacramento, California, USA.

Williams, J.R., 1960. Studies on the nematode soil fauna of sugar cane fields in Mauritius. 4. Tylenchoidea (partim). Occasional Papers, Mauritius Sugar Industry Research Institute, 4:1-30.