Predatory nematodes by AALIYA TAIYAB

1. A predatory nematode eating another
nematode
Stoma StRUCtURE IN
PREDatoRY NEmatoDES
By :-
Aaliya Taiyab
M.Sc. Final Zoology
Sem IV
A.M.U
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2.  In soil most common groups of nematodes are :-
 Bacterial feeders,
 Fungal feeders,
 Plant parasites,
 Predators, and
 Omnivores.
 Predatory nematodes feed on protozoa and other soil nematodes. Since
the predator has to feed upon active prey, it must have a mechanism to
grasp the active prey and then to cut or puncture its cuticle.
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3. Soil inhabiting predaceous form are grouped into different feeding types:
Type I: They feed by cutting the body of prey and then sucking its body contents as they
are unable to engulf intact preys.Diplogasterid.
Type II: They feed by a combined action of cutting and sucking as well as at times
engulfing the whole prey. Mononchida
Type III: They feed only by puncturing or piercing the cuticle of the prey and then
sucking the body contents.Dorylaimida and Aphelenchida. (Seinura sp.)
Mononchus Dorylaimus Aquatides Actinolaimus Seinura 3

4. STOMA: Basic Structure
• Buccal cavity and buccal capsule make up the stoma
De Ley et al. (1995) – based on TEM :-
1. Cheilostom
2. Gymnostom
3. Stegostom
Cheilostom
Gymnostom
prostegostom
mesostegostom
metastegostom
telostegostom
Stegostom
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5.  Movable and immovale stomal
structures (armature)
 Odontia and onchia
 Dentate and denticulate
 Fossoria or mandible
 Protrusible spear
odontia onchia
Mandibles Protrusible spearDentate and denticulate 5

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7.  Mononchida
 Walls-heavy sclerotisation –thick and very prominent
 Made up of two sets of three plates
1. anterior- vertical
2. posterior – oblique plates
 Each set – 3 plates (tripartite)
1. one dorsal – dorsal tooth. Non movable, vary in position, shape and
size.
2. two subventral walls – may or may not bear tooth, teeth or
denticles. When present these are known as subventral or submedian
armature
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8. On the basis of shapes
 Mononchoidea : barrel shaped with tapering base
 Anatonchoidea : with flat base
 Bathyodontoidea : long cylindrical, thin walled
Shape :- barrel shaped, globular, oval, rectangular or long cylindrical, thin
walled.
A: Mononchus
B: Clarkus
C:Coomansus
D: Mylonchulus
E:Sporonchulus
F: Cobbonchus
G: Prionchulus
H: Anatonchus
I: Iotonchus
J: Miconchus
K: Hadronchus
L: Mononchulus
M; Oionchus
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9. •Absent :- Mononchus, Coomansus,
Iotonchulus
•Identical to dorsal tooth :- Miconchus, Or
although similar in sizes, shape and position,
pointing posteriad as in Anatonchus , or
located slightly posterior as in Cobbonchus
•Subventral teeth are several & are arranged
in single longitudinal row on each cell (eg.
Actus) or a ‘rib like’ structure along the row of
teeth as in Prionchulus
•Subventral teeth are numerous and are
arranged in almost regular transverse rows
as in Mylonchulus but are irregularly
scattered in Sporonchulus
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10. Rhabditida
Rhabditina Diplogasterina
(predators)
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11.  Diplogasterina
 Cutting and Sucking type
 Cheilostomal plates/rugae help in grasping
the prey
 gymnostom
 Stegostom bear dorsal tooth which differ in
shape and sizes and seems to be the main
killing weapon
 It receives the duct from the dorsal
pharyngeal gland, it ejects the secretions
on the prey for extra- corporal digestion.
Examples:Diplogaster, Mesodiplogaster,
Butlerius, Mononchoides, Fictor,
Neodiplogaster, represents some of the
predatory diplogasterids
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14.  Protrusible stylet which is responsible for penetrating/puncturing the prey
cuticle/host plant.
 Basic structure:
o Vestibulum
o Guiding apparatus axial spear or odontostyle
o Stomal armature
o Muscles
Dilator muscles
Protracror muscles
Retractor muscles
Mural tooth
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15. 1. Axial Spear (Dorylaimina):-
 Odontostyle + odontophore
 Vestibulum more prominent
 Guiding ring better developed
 Odontostyle broader and centrally placed and
has a dorsal aperture
 odontophore formed by cuticularisation of the
anterior part of oesophastom, used for
supporting & ejecting mechanism for the
odontostyle
2. Mural tooth (Nygolaimina)
 Thin walled vestibulum
 Weakly developed guiding ring
 Well cuticularised double walled guiding sheath
 Lies posteriorly in the left ventrosublateral
 Narrow, without aperture and placed
asymmetrically
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16.  Aporcelaimidae
 Comprises exclusively of predatory forms
 Well developed widely seperated lips
 Hexagonal oral aperture
 Plicated guiding ring
 Wide odontostyle with wide aperture,
Aporcelaimus : aperture occupying more then
one-half length
 Qudsianematidae
 Odontostyle cylindrical, dorylamoid with wide
lumen and aperture. Guiding ring single or
double. Odontophore rod like or with
sclerotised basal flanges or knobs.
 Labronema and labronemella : the lips are
more developed for grasping the active prey
and the odontostyle and odontophore are
more strong
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17. Discolaimus: lips are further widened and
become disc like to form an arch over the
oral aperture, odontophore very sharply
pointed with an aperture about 50% of its
length
Carcharolaimus, Carcharoides, Caribenema:
strong basket like cheilostomal sclerotisation
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18. Actinolaimidae
•Exclusively predatory forms
•Characterised by presence of four large
tooth/onchia, teeth and denticles.
•Vestibule wide, vestibular ring –single or double
forming a crown with large no. of prongs around
oral aperture., adapted for grasping the active
prey
•Onchia generally separated from each other
(Actinolaimus sp., Neoactinolaimus sp.,) but
sometime basally fused; ring like structure
(Metactinolaimus)
metactinolaimus 18

19. Vestibular wall may be corrugated and
provided with denticles (Paractinolaimus
sp., westindicus sp.,)
•Onchia may be simple or provided with
secondary tooth (Neoactinolaimus sp.,)
•Scleroactinolaimus punctatus: cheilostom
in addition to onchia is provided with four
strongly sclerotized plates
•Westindicus sp., : vestibule consist of
numerous ribs forming a basket-like
structure.
Paractinolaimus Westindicus
Neoactinolaimus
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20. Tylenchida
Tylenchina Aphelenchina
Predatory : Seinura
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21.  Seinura and Laimaphlenchus
 Small narrow spear with a fine lumen but
without basal knobs
 Spear – piercing and sucking type
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22.  Exhibit diversity in terms of stomal
armature Less explored in terms of
feeding habit mostly marine .
 Predatory enoplids grips its prey with
the three eversible teeth and the
cylindrical pharyngeal cavity acts as
a sucking organ.
 Largerly Stoma contains three
mandibles
 Oncholaimidae: feed on other
nematodes
 Large capsuliform, cheilostomal
stoma
 Onchomailus : left subventral tooth
is largest
 Thalassogenus: interesting marine
oncholaimid
Oncholaimus 22

23.  Ironidae ; mainly predatory forms –
anterior feeding apparatus consist of
three parts:
o Large part cheilostomal in origin that
leads into oesophastom.
o Median part-double walled cylinder
like : three equal teeth are present
o Proximal part of oesophastom :
oblique radial muscles
 Ironus: cheilostom triangular in shape
Ironus
Thalassironus
Trissonchulus
Thalassironus sp. –two
dorsal tooth with apices
pointing in different
directions whereas in
Trissonchulus sp., the two
dorsal teeth are fused at
base and the cheilostomal
wall is denticulate
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In the absence of prey, some nematodes can switch to omnivorous
mode of feeding. Ex dorylaims

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