Lecture 5 Classification of Nematodes on the basis of Phytoparasitism 4/2/2017 Walia CCSHAU

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% 4/2/2017 Walia CCSHAU

Parasites of below ground part parts Parasite of below ground plant parts Ectoparasites Migratory Sedentary Semi-endoparasites Endoparsites 4/2/2017 Walia CCSHAU

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 4/2/2017 Walia CCSHAU

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 4/2/2017 Walia CCSHAU

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, Hemicycliophora arenaria Sessile nematode, Cacopaurus pestis 4/2/2017 Walia CCSHAU

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, Tylenchorhynchus group 4/2/2017 Walia CCSHAU

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, Tylenchulus semipenetrans Reniform nematode, Rotylenchulus reniformis 4/2/2017 Walia CCSHAU

Sedentary Semi-endoparasites Examples Reniform nematode, Rotylenchulus reniformis Citrus nematode, Tylenchulus semipenetrans 4/2/2017 Walia CCSHAU

Endoparasites Migratory endoparasites 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 4/2/2017 Walia CCSHAU

Migratory Endoparasites 4/2/2017 Walia CCSHAU

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 4/2/2017 Walia CCSHAU

Sedentary Endoparasites 4/2/2017 Walia CCSHAU

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 4/2/2017 Walia CCSHAU

Anhydrobiosis 4/2/2017 Walia CCSHAU

Parasites of above ground plant parts Gall forming Wheat seed gall nematode, Anguina tritici Leaf gall nematode, Anguina balsamophila Non-gall forming Stem nematode, Ditylenchus dipsaci, D. angustus Foliar nematode, Aphelenchoides fragariae, A. ritzemabosi Associates of insects Pine wood nematode, Bursaphelenchus xylophilus Red ring nematode, Bursaphelenchus cocophilus 4/2/2017 Walia CCSHAU

4/2/2017 Walia CCSHAU