Rotylenchulus reniformis

Rotylenchulus reniformis (Reniform nematode, Kidney-shaped nematode) is a nematode, a type of roundworm, in the Family Hoplolaimidae. It is called the reniform (kidney-shaped) nematode because the female curls her exposed posterior as she feeds. It is an important parasite that attacks a wide variety of crops and other plants. It is classified in parasitology as a cyst-forming nematode that prefers to attack the roots of its host plant. R. reniformis favors sandy loamy soils.

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Life cycle

R. reniformis is both an ectoparasite (on the surface of the plant) and a semiendoparasite (partially inside the plant). The males are ectoparasitic and do not seem to affect the plant very much, texts classify them as nonpathogenic.^[1] The females borrow into the roots and form a cysts, but leave part of their body (the posterior) outside the root, for copulation and egg-laying. After mating, the female lays some 30 to 75 eggs outside the root in a gelatinous mass containing. The matrix keeps the eggs moist and inhibits other animals from consuming the eggs. The eggs hatch in 8-10 days and the larvae molt three or four times and then develop into male and females; however, only females have been observed feeding. The life cycle is completed in 17 to 23 days.^[2]

Disease symptoms

R. reniformis causes hypertrophy in the pericycle cells of root seedlings and in the periderm cells of the roots of 4-5 week old plants.^[3] Generally root growth is reduced and there are few large roots, instead numerous coarse and stubby lateral roots are present. Diseased plants can become severely stunted and chlorotic (yellow), and may wilt. Wilting is often caused by opportunistic parasites such as the Fusarium wilt on cotton. Root decay is usually caused by secondary fungi infection.

Control

Chemical control prior to planting is effective. Crop rotation is relatively ineffective since R. reniformis lives on most crop roots. In irrigated areas, drying out the field for a year will significantly reduce the presence of R. reniformis and other nematodes.^[3][4] Paecilomyces lilacinus, a fungal egg parasite, has been used as a biological control.^[5]

Distribution

R. reniformis has worldwide distribution in tropical and subtropical areas, including Texas and the southeastern United States. It has numerous hosts, including fruit trees, lentil, cotton, cowpea, pigeonpea, tea, tobacco, soybean, pineapple, bananas, sweet potato, alfalfa, corn, asparagus, palm, cucumber, squash, melon and ginger.

Notes

References

• Rotylenchulus reniformis NCBI Taxonomy ID: 239373 via Taxonomy Browser
• Maggen, Armand R. (1987) "A reappraisal of Tylenchina (Nemata): 2. Classification of the suborder Tylenchina (Nemata : Diplogasteria)" Revue Nématologie 10(2): pp. 135-142
• Siddiqi, Mohammad Rafiq (1985) Tylenchida parasites of plants and insects Commonwealth Institute of Parasitology, Commonwealth Agricultural Bureaux, Farnham Royal, Slough, UK, ISBN 0-85199-943-3
• Geraert, Etienne (2006) Functional and detailed morphology of the Tylenchida (Nematoda) Brill, Leiden, ISBN 90-04-14895-7
• Oteifa, Bakir A. (Aug., 1970) "The reniform nematode problem of Egyptian cotton production" The Journal of Parasitology 56(4): Section 2, Part 1: Supplement: Second International Congress of Parasitology, Resumes Nos. 1-702., pp. 1-389, p.255