Classification and general-characters.pdf

nematode

1. Classification of nematodes
Course: B.Sc. Agriculture
SemII
Subject: Introductory nematology
Unit: 2

2. •Classification of nematodes uptofamily level with emphasis on
groups containing economically important genera.
•Classification of nematodes by habitat. Identification of
economically important plant nematodes uptogeneric level with
the help of keys and description.
Unit 2

3. ECOLOGICAL CLASSIFICATION OF NEAMATODE
( BY HABITAT)
Therearetwomajorclasses
I.Abovegroundfeeder
II.Belowgroundfeeder
I.Abovegroundfeeder
a.Feedingonflowerbuds,leavesandbulbs
i)Seedgallnematode:Anguinatritici
ii)Leafandbudnematode:Aphelenchoides
iii)Stemandbulbnematode:Dictylenchus
b.Feedingontreetrunk
i)Redringnematode:Rhadinaphelenchuscocophilus
ii)Pinewiltnematode:Bursaphelenchusxylophilus

4. II.Bellowgroundfeeder
Itisagainclassifiedintothreeclasses
I)Endoparasiticnematodes
II)Semiendoparasiticnematodes
III)Ectoparasiticnematodes
a)Endoparasiticnematodes
Theentirenematodeisfoundinsidetherootandthemajorportionofnematode
bodyfoundinsidetheplanttissues.Theyaretwotypes
1)Migratoryendoparasite:-Thesenematodesmoveincorticalparenchymaof
hostroot.Whilemigratingtheyfeedoncells,multiplyandcausenecroticlesion.
Example,Pratylenchusspp.,Radopholusspp.andHirschmanniellaspp.
2)Sedentoryendoparasite:-thesecondstagelarvaepenetratetherootletsand
becomesedentarythroughoutthelifecycle,insidetherootcortex.Examples,
Heteroderaspp.andMeloidogynespp.

5. b)Semiendoparasiticnematodes
Theanteriorpartofnematode,headandneckbeingpermanentlyfixedin
thecortexandtheposteriorpartextendsfreeintothesoil.Examples,
RotylenchulusreniformisandTylenchulussemipenetrans.
c)Ectoparasiticnematodes
Thesenematodeslivefreelyinthesoilandmovecloselyoron
therootsurface,feedintermittentlyontheepidermisandroothairneartheroot
tip.Theyaretwotypes,
1)Migratoryectoparasites:-Thesenematodesspendtheirentirelifecyclefree
inthesoil,feedingexternallyonthehostplants,depositeggsinsoil.Whenthe
rootsaredisturbedtheydetachthemselves.Examples,Criconemoidesspp.,
Paratylenchusspp.andsspp.,etc.
2)Sedentoryectoparasites:-Inthistypeofparasitismtheattachmentof
nematodetotherootsystemispermanentbutforthis,itissimilartotheprevious
one.Examples,HemicycliophoraarenariaandTrichodorusspp.,etc.

6. IMPORTANTPLANTPARASITICNEMATODES
1) Root-knot Nematode, Meloidogynespp.
Systematic Position:-
Order-Tylenchida
Sub order -Tylenchina
Super family -Tylenchoidea
Family -Heteroderidae
Sub family -Meloidogyninae
Genus-Meloidogyne
Species -
i) incognita
ii) javanica
iii) arenaria
iv) hapla

7. Parasitism&Habitat:-
i)FemalesandIII&IVstageoflarvaeareSedentoryendoparasites.
ii)MalesandIIstagelarvaearemigratory.
Morphologicalcharacters:-
i)Body-ElongatelarvaeandmaleTypicallysaccate,spheroidwitha
distinctneckinfemales.
ii)Stylet-Inmales,Strongwithroundedknob&Infemales,moreslender
thanmales.
iii)Oesophagous-Withlargemedianbulbfollowedbyshortisthumus.
iv)Excretorypore-Oftenseenwithpartofexcretorytubeinthearea
betweenposteriorpartofstyletknobsandoppositetomedianbulb.
v)Vulvas&anus-Femalestypicallyoppositetoneckandsurroundedbya
patternoffinelineslikehumanfingerprint.(Perennialpattern)
vi)Spicule-VeryneartheterminusofmalesBursaisabsent.

8. Symptoms:-
-Yellowing of leaves
-Stunted growth
-Reduced vigor
-Reduced size & number of fruits
-Gall formation
-Multinucleate cell –Giant cell (Nurse cell)
-Hypertrophy –Enlargement of cell
-Hyperplasia –Multiplication of cell
Control:-
-Two to three deep Ploughing
-Rotation with cereal crops
-Apply carbofuron(Furdan3G) @ 7 g/m2
-Resistant varieties of Tomato eg. HisarLalit, PNR 7

9. 2) Reniform Nematode, Rotylenchulus reniformis
Systematic Position:-
Order -Tylenchida
Sub order -Tylenchina
Super family -Hoplolaimoidea
Family -Hoplolaimidae
Sub family -Hoplolaiminae
Genus -Rotylenchulus
Species -reniformis

10. Parasitism&Habitat:-FemalesareSemiendoparasiticonmany
plants.
Morphologicalcharacters:-
i)Body-Malesandimmaturefemalesareslenderandsmall,adult
femalesarekidneyshaped
ii)Oesophagous-Dorsaloesophagealglandsopensaboutonestylet
lengthposteriortostyletknobs.
Symptoms:-
Yellowingofleaves,delayedgermination,reducedplantgrowthand
vigor,stuntedgrowth,browningofrootsduetopenetrationof
nematodearethegeneralsymptomsofthisnematode.Youngand
tenderplantsaremorevulunerabletonematodeattack.

11. 3)Root-lesionNematode,Pratylenchusspp.
SystematicPosition:-
Order-Tylenchida
Suborder-Tylenchina
Superfamily–Tylenchoidea
Family-Pratylenchidae
Subfamily-Pratylenchinae
Genus-Pratylenchus
Species-i)coffeae-Citrus,Banana&coffee
ii)zeae-Maize
iii)thornei–Pulses
Parasitism&Habitat:-
-Migratoryendoparasites
-Feedingonrootcortexofmanycrop/plant
-Allstagesfoundinrootorsoil.

12. Morphological characters:-
i) Body length -0.4-0.8 mm.
ii) Lip region -Slightly set-off from body.
iii) Stylet-Typically short, strong with massive knob.
iv) Ovary -Monodelphic
v) Vulva -Posterior fourth of the body (75-80%).
vi) Tail -Nearly round to pointed and in males, the tail has bursa.
Symptoms:-
Lateemergenceofseedlings,lessgerminationandstuntedgrowth
withnecroticlesionsontherootsurfacewhichareinitiallysmall
coalesceatthelaterstageandcausedeathoftherootlets.Root
systemisreduced.
Control:-
-Raise nursery in nematode free soil
-Pull and burn infected plants

13. 4) Spiral Nematode, Helicotylenchusspp.
Systematic Position:-
Order -Tylenchida
Sub order -Tylenchina
Super family -Tylenchoidea
Family -Hoplolaimidae
Sub family -Rotylenchoidinae
Genus -Helicotylenchus
Parasitism & Habitat:-Endoparasiticand ectoparasiticon many plants
Morphological characters:-
i) Body -Arcuateto ‘C’ shape when relaxed
ii) Stylet-Moderately long, typically located more than one half styletlength
posterior to styletknobs.
iii) Ovaries -Two (didelphic)
iv) Vulva -Posterior to middle of body (60-70%)
v) Tail -In females, rounded to nearly pointed often with short projection on ventral
side and In males, tail is short with bursa.
Symptoms:-The nematodes attack root cortex and produce necrotic lesions.

14. 5)CystNematode,Heteroderaspp&Globoderaspp.
Cystmeansanyabnormalmembranoussacorblisterlikepouchcontaining
fluid.
SystematicPosition:-
Order-Tylenchida
Suborder-Tylenchina
Superfamily-Tylenchoidea
Family-Heteroderidae
Subfamily-Heteroderinae
Genus-i)Heterodera
ii)Globodera

15. SpeciesofHeterodera-
i)avenae-Cerealcystnematode(wheat&barley)foundinnorth
India
ii)zeae-Maizecystnematode
iii)cajani-Pigeonpeacystnematode(tur,mung,Udid&cowpea)
iv)oryzicola-Ricecystnematode(rice&banana)foundinKerala,
M.P.,Orissa&WestBengal.
SpeciesofGlobodera-
i)rostochinensis-PotatocystnematodeorGoldennematode
ii)pallida
Hostplants-Potato,Tomato&Brinjal
Parasitism&Habitat:-
Parasiticonmanyplantsmostlyintemperatezone(Notablypotatoes,
sugarbeets,oats&othergrains,clover,soybean&various
cruciferous).

16. Morphological characters:-
i) Body -Slender in males (1.0-2.0 mm) and larvae (0.3-0.6 mm) In
females, typically swollen, lemon shaped (0.5-0.8 mm)
ii) Colour-White or yellow, cyst dark brown, lemon shaped (0.8 mm long
& 0.5 mm wide) or nearly same shape as that Meloidogynefemale.
iii) Stylet-Short in males with rounded basal knobs & in larvae, more
than 0.02 mm long.
iv) Oesophagous-With well-developed median bulb & lobe extending
back & overlapping the intestine.
v) Spicule-Near the posterior end of males
Globodera-Similar to Heteroderaspp. slight difference in adult females
are globular (rounded) in shape and hence the genus is named as
Globodera.

17. Symptoms:-
Heterodera-Thediseasedplantsshowyellowingofleaves,stuntedgrowth,
reducedtillering.Earheadsifformedareverysmallknownas‘Molya’
disease’
Globodera-Typicalsymptomsofheavyinfestationarestuntedplantswith
unhealthyfoliage,prematureyellowing,poordevelopmentofrootsystem,
reductioninsizeandnumberoftubers.Suchplantsexhibittemporary
wiltingduringhotterpartoftheday.
Control:-
Heterodera
-Two-threesummerploughingat10-15daysinterval.
-RotationwithMustard,chickpea
[email protected]./ha.
Globodera
-Rotationwithpea,cabbage,carrot,cauliflowerduringautumnseason.
-Growresistantvarietiesofpotatoes-KufriSwarna,KufriThenmalai

18. 6)DaggarNematode,Xiphinemaspp.
SystematicPosition:-
Order-Dorylaimida
Suborder-Dorylaimina
Superfamily-Dorylaimoidea
Family-Longidoridae
Subfamily-Xiphineminae
Genus-Xiphinema
Parasitism&Habitat:-Migratoryectoparasites
Morphologicalcharacters:-
i)Body-Femaleselongate,cylindrical,formingopenspiralwithagreater
curvatureinposteriorhalf.
ii)Stylet-Typicallylong..
iii)Ovaries-Monodelphicordidelphic.
iv)Vulva-Situatedatmiddleofbody.
v)Tail-Bluntlyroundedorwithprojectionsonventralsideinbothmalesand
females.
vi)Malesextremelyrear,notessentialforreproduction.
Symptoms:-Attackedrootsshownecrosis,lackoflaterals,terminalswelling,
rootgallingetc.

19. 7)RicestemNematode,Dictylenchusangustus
SystematicPosition:-
Order-Tylenchida
Suborder-Tylenchina
Superfamily-Tylenchoidea
Family-Anguinidae
Subfamily-Anguininae
Genus-Dictylenchus
Species-angustus
Morphologicalcharacters:-
i)Body-Femalesswollen,whenrelaxed‘C’shaped.
ii)Stylet-Smallwithdelicateknob.
iii)Oesophagous-Basaloesophagealbulbnotoverlappingtheintestine,cardia
absent.
iv)Vulva-Situatedinposteriorregionofbody.
v)Ovary-SingleProdelphic.
vi)Tail-Elongate.
vii)Malessimilartofemalesbutmoreslendercaudalalaesubterminal.

20. DiseaseCaused:-AlfadiseaseofRice.
Symptoms:-
Atvegetativephase,yellowingorwhitesplashpatternofleafsheath
wheremarginsbecomeconcorted.Latersplashpatternsdevelop
brownishstainsandinternodesandstemsturnblack.
Atthereproductivephase,thenematodecollectsaroundthefloral
primordiaandfeeduponthedevelopingearheads.Earheadsemerges
ascrinkledortwistedwithemptyspiklets(ripeufra)ordoesnot
emergeatall(swollenufra).

21. 8)CitrusNematode,Tylenchulussemipenetrans
SystematicPosition:-
Order-Tylenchida
Suborder-Tylenchina
Superfamily-Criconematoidea
Family-Tylenchulidae
Subfamily-Tylenchulinae
Genus-Tylenchulus
Species-semipenetrans
Parasitism:-Endoparasiticonrootsofcitrusandotherplants.
Maturefemalesaresemiendoparasitic.

22. Morphologicalcharacters:-
i)Body-Smallallstages.Maturefemalesswollen.
ii)Stylet-Smallinlarvaesandmales,welldevelopedinmaturefemales.
iii)Oesophagous-Withdistinctposteriorbulbinlarvaeyoungmalesand
immaturefemales.
iv)Vulva-Prominentinposteriorendofyoungandadultfemales.
v)Excretorypore-Typicallysituatedposteriorlyinprotuberancejustanteriorto
vulva.
vi)Anus-Absentordifficulttoseeinimmaturestages.
vii)Bursa-Absent.
Symptoms:-
Thediseasedtreesshowreductioningrowthandvigorwithyellowingofleaves.
Suchtreesshowgradualdiebacksymptomsstartingfromtheuppermostportion.
Rootsofinfectedtreesappearlargerindiameteranddarkerthanthehealthytrees
mainlyduetoadherenceofsoilparticlestothegelationousmatrixexcretedbythe
adultfemales.Cortexofhighyinfestedfeederrootsdecaysandgetssloughedoff
easily.

23. 9)BurrowingNematode,Radopholussimilis
SystematicPosition:-
Order-Tylenchida
Suborder-Tylenchina
Superfamily-Tylenchoidea
Family-Pratylenchidae
Subfamily-Pratylenchinae
Genus-Radopholus
Species–similus
Parasitism:-EndoparasiticonrootsofBananaandcitrus.

24. Morphologicalcharacters:-
i)Body-0.4-0.9mminlength.
ii)Lip-Roundedinfemales,setoffandknoblikeinmales.
iii)Stylet-Shortandstoutinfemales,slenderandrudimentaryinmales.
iv)Oesophagous-Formingalobe,dorsallyoverlapstointestine.
v)Vulva-Locatedatmiddleofthebody.
vi)Ovaries-Didelphic
vii)Tail-Bluntendinfemalesandmalelongtailwithbursa.
Symptoms:-
Inbanana,bearingplantsshowpoorgrowthandsmallfruitsize,
pronetotopplingoverunderhighwindpressure.Thenematodecauses
woundingofrootsresultinginreddishbrowncorticallesionswhichare
clearlyvisiblebysplittingtheaffectedrootslongitudinally.Purplish
streaksontheyoungroots.Thelesionsleadtotheformationoftunnels
andcavitiesintheroots.Theinfectionspreadstoyoungsuckersalsoin
whichnecrotictissuesdevelop.

25. Web reference:
http://www.agri.kkwagh.edu.in/Theory%20N/ENTO-364.pdf