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Lecture 5 Classification of Nematodes on the basis of Phytoparasitism

Lecture 5 Classification of Nematodes on the basis of Phytoparasitism. Habitat. Majority (90%) of PPNs attack roots or other below ground plant parts such as tubers, rhizomes, suckers, bulbs etc. Ectoparasites 60% Endoparasites 30%

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Lecture 5 Classification of Nematodes on the basis of Phytoparasitism

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  1. Lecture 5Classification of Nematodes on the basis of Phytoparasitism Walia CCSHAU

  2. Habitat • Majority (90%) of PPNs attack roots or other below ground plant parts such as tubers, rhizomes, suckers, bulbs etc. • Ectoparasites 60% • Endoparasites 30% • Only a few forms (10%) attack above ground parts such as leaves, stems, buds, inflorescence etc. • Ectoparasites 2% • Endoparasites 8% Walia CCSHAU

  3. Parasites of below ground part parts Walia CCSHAU

  4. Ectoparasites • Spend entire life cycle in soil, all life cycle stages, including eggs in soil • Only stylet is inserted into roots, body remains outside • A vast majority of ectoparasites feed on root hairs and epidermal cells • Not considered very damaging, except for some groups Walia CCSHAU

  5. Ectoparasites • Migratory (Vagrant ectoparsites) • Feed at a particular site very briefly and then move to another site • Remain vermiform, eggs scattered in soil • Examples • Awl nematode, Dolichodorus • Sting nematode, Belonolaimus • Dagger nematode, Xiphinema • Needle nematode, Longidorus • Stubby root nematode, Trichodorus, Paratrichodorus Walia CCSHAU

  6. Ectoparasites • Sedentary (Sessile) ectoparasites • Feed at a site for long period • Very sluggish in movement • Have coarse striation or annulations on cuticle • Criconematid group having small bodies and long stylets relative to their body fall in this category • May secrete an adhesive plug to fix the stylet into the root • Examples • Sheath nematode, Hemicycliophoraarenaria • Sessile nematode, Cacopauruspestis Walia CCSHAU

  7. Semi-endoparsites The anterior portion of the body is embedded into the plant tissues • Migratory semi-endoparasites • Remain vermiform • Do not establish a permanent feeding site in plant tissues • Rarely the entire body may be inside the plant tissues • Examples • Spiral nematode, Helicotylenchus • Lance nematode, Hoplolaimus • Stunt or Stylet nematode, Tylenchorhynchusgroup Walia CCSHAU

  8. Semi-endoparasites • Sedentary semi-endoparasites • Establish a permanent feeding site inside plant tissues • Do not move after infection • Eggs are deposited in masses around the body of females; fecundity is more - about 40-80 eggs per female • The posterior part of females outside the root becomes swollen to varying degrees • Citrus nematode, Tylenchulussemipenetrans • Reniform nematode, Rotylenchulusreniformis Walia CCSHAU

  9. Sedentary Semi-endoparasites • Examples • Reniform nematode, Rotylenchulus reniformis • Citrus nematode, Tylenchulus semipenetrans Walia CCSHAU

  10. Endoparasites • Migratoryendoparasites • All stages (except egg) can cause infection, and are present in soil initially • Complete the entire life cycle in side plant tissues • Feeding, migration, growth, reproduction, and oviposition take place in plant tissues • Biological activities confined to cortex only; eggs are laid scattered, fecundity around 25 eggs per female • Do not induce any special feeding area • Any stage can leave the roots and come out into the soil due crop senescence of tissue destruction • Lesion or Meadow nematode, Pratylenchus • Rice root nematode, Hirschmanniella • Burrowing nematode, Radopholus Walia CCSHAU

  11. Migratory Endoparasites Walia CCSHAU

  12. Endoparasites • Sedentary endoparasites • Evolutionary most advanced and most damaging among all PPNs • Only a particular stage (J2) of life cycle infective • Induce special feeding areas, involving vascular tissues • Females become swollen to varying degrees after infection and do not move • Eggs laid in masses either inside the female body or outside in an eggmass • Fecundity is high (200-500 eggs per female) • Root-knot nematode, Meloidogyne • Cyst nematode, Heterodera, Globodera Walia CCSHAU

  13. Sedentary Endoparasites Walia CCSHAU

  14. Parasites of above ground plant parts • Specially adapted to feed on leaves, stems, buds, inflorescence etc. • May feed ecto- or endoparasitically • Do not produce any special feeding area • Can crawl up the plant in a thin film of water • Eggs are deposited in plant tissues • Usually undergo anhydrobiosis at crop maturity or under moisture stress; a particular stage of life cycle only undergoes quiescence • Can remain dormant for varying periods, revive upon availability of moisture Walia CCSHAU

  15. Anhydrobiosis Walia CCSHAU

  16. Parasites of above ground plant parts • Gall forming • Wheat seed gall nematode, Anguinatritici • Leaf gall nematode, Anguinabalsamophila • Non-gall forming • Stem nematode, Ditylenchusdipsaci, D. angustus • Foliar nematode, Aphelenchoidesfragariae, A. ritzemabosi • Associates of insects • Pine wood nematode, Bursaphelenchusxylophilus • Red ring nematode, Bursaphelenchuscocophilus Walia CCSHAU

  17. Walia CCSHAU

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