Reniform nematode Rotylenchulus reniformis

1. Reniform nematodeRotylenchulusreniformis Walia CCSHAU

2. Etymology & Historical • Genus first created by Linford & Oliviera in 1940 – recorded in USA on cowpea • Sivakumar & Seshadri 1963 first reported from India • Rotylenchulus is a Latin diminutive of genus Rotylenchus • Rotylenchus derived from Tylenchus robustus • Reniform after the kidney-shaped females Walia CCSHAU

3. Systematic Position Walia CCSHAU

4. Diagnostic Characters • Mature females • Kidney-shaped, irregular, body length up top 0.5 mm; dorsal oesophgeal gland empties into oesophagus about one stylet length behind knobs; vulva raised, in the posterior half of the body; ovaries two, reflexed. • Immature females • Vermiform; acquires typical C shape in the posterior half when heat relaxed; head region conoid, cephalic sclerotization prominent and stylet well developed; vulva in the posterior half of the body; tail conoid with rounded terminus. • Male • Vermiform; cephalic sclerotization, stylet and oesophagus reduced; tail pointed; bursa not reaching up to tail tip. Walia CCSHAU

5. Walia CCSHAU

6. Mature female Male Immature female Walia CCSHAU

7. Distribution and Hosts • Widespread in tropical and Subtropical areas of the world • Prevalent in most states in India • Host range very vast • Vegetable, Fruit, Pulse, Fiber crops & ornamentals • Problem on Cotton, castor, cowpea, coffee, grapes, pineapple, papaya, vegetables and pulses Walia CCSHAU

8. Biology and Life Cycle • Sedentary semi-endoparasite • Infective stage – Pre-adult female (Immature female) • Becomes mature female within 7-10days after infection • Eggs (40-80 per female) deposited in mass around female body • J2 hatches from egg, comes out in soil • Three Superimposed moults in soil to become immature female/male • Male vermiform, non-parasitic, remains in soil, required for reproduction • Life cycle 25 days at 25-30 C • More prevalent in loamy and clay loam soils • Two host races • Race A - Castor, Cotton, Cowpea • Race B = Multiplies on cowpea only Walia CCSHAU

9. Walia CCSHAU

10. Walia CCSHAU

11. Mature females attached to root Walia CCSHAU

12. Mature females attached to root Walia CCSHAU

13. Single female attached to root Walia CCSHAU

14. Females attached to roots Walia CCSHAU

15. Female with eggmass Walia CCSHAU

16. Females with eggmasses Walia CCSHAU

17. Females covered with eggmasss Walia CCSHAU

18. Symptoms and Losses • Above-ground • No diagnostic symptoms • General stunting, yellowing of leaves, wilting, reduction in size and number of fruits • Below-ground • Necrosis, destruction of feeder roots • Losses • 40-60% losses in cotton in Louisiana (USA) • 10-15% losses in cotton in TN (India) Walia CCSHAU

19. Histopathology • Establishes a permanent feeding site • Some pericycle cells in the vicinity of nematode head become hypertrophied • Partial dissolution of cell walls takes place • A multinucleate mass of cells – Prosyncyte – is formed • About 150-200 cells around prosyncyte become modified (dense cytoplasm) but remain uninucleate • Phloem and endodermal cells may also be modified in some hosts Walia CCSHAU

20. Histopathology - Comparative Walia CCSHAU

21. Histopathology - Comparative Walia CCSHAU

22. Histopathology - Comparative Walia CCSHAU

23. Interaction • Plays important role in Fusarium and Verticillium wilts • Increases the severity and incidence of wilts in cotton • Fungus alone – 10% wilt • Fungus + Nematode - 81% wilt Walia CCSHAU

24. Management • Deep summer ploughing • Grow non-hosts like onion, garlic, carrot • Nematicidal coating in bold seeded crops – carbosulfan 3% w/w Walia CCSHAU