ONE OF THE TOPIC IN CHAPTER 4 PLANT PATHOLOGY SEMESTER 2

1. Characteristics of
Nematodes
AGR154

2. Chapter Overview
Characteristics of nematode
Reproduction of nematodes
How nematodes affect plant
Isolation of nematodes from soil

3. Introduction
Kingdom = Animalia
Phylum = Nematoda
Important genus:
Heterodera = cyst nematode
Meloidogyne = root-knot nematode
Live in fresh or salt water or in the soil

4. Morphology of Plant Pathogenic
Nematodes
Small , 300 to 1000 micrometers long
15-35 micrometers wide (invisible to naked
eyes)
Eel shape and round in cross section
Smooth, unsegmented bodies
Without legs or other appendages

5. Anatomy
More or less transparent (covered by a colorless
cuticle)
The cuticle is produced by the hypodermis
The cuticle will extend to the body cavities as four
chords
The four chords will separating into four bands of
muscles
The muscles enable the nematode to move
Body cavity contains a fluid – circulation and
respiration take place)

6. Anatomy
Hollow tube digestive systems- starting from
mouth- esophagus- intestine – rectum and anus.
6 lips surround the mouth
Have a hollow stylet or spear (use to puncture
holes in plant cells and take the nutrients from
cell)

7. Reproduce through eggs
May be sexual or parthenogenetic (development
of embryos occurs without fertilization by a male)
1. Female reproductive system
One or two ovaries
Followed by oviduct and uterus terminating in a
vulva
2. Male reproductive system
Has testis and seminal vesicle
Has a pair of protrusible and copulary spicules
Reproduction

9. Cross Section of Female
Nematodes

10. Nematodes Lips

11. Life Cycle
4 steps/phases
Eggs
4 juvenile stages
Adult
Egg produced

13. Eggs hatch into juvenile
Juveniles will enlarge
There are 4 stages of juvenile
Each stages will be ended with molting process
The first molt occurs in the eggs
After the final moult, the nematodes will
differentiate into males or females.
The female can then produce fertile eggs

14. Life Cycle

16. The life cycle may be completed within 2-4
weeks under optimum environmental
Usually the first and second juvenile still
could not infect the plant
Once infective stages are produced, they must
feed the host
Without host, they might die due to starvation.

17. Habitat
Mostly all of plant pathogenic nematodes spend their
life in the soil
1. Feeding habit
Ectoparasite : do not enter into the host tissue
feed only on the host surfaces
Endoparasite : enter and feed the host tissue
2. Feeding sites
Migratory : Moves through plant tissue
Sedentary : establish specialised feeding sites
& stay there until they die.

18. Location of Feeding
Location of
feeding
Feeding habit Example
Endoparasite Migratory Root knot, cyst, citrus
Sedentary Lesion, stem, bulb
Ectoparasite Migratory Ring
Sedentary Stubby root

19. How Nematodes Affect Plant
Because of feeding process
Puncture a cell wall
Inject saliva- contain enzymes
Take the cell contents
And moves on within a few seconds

20. Isolation of Nematodes From
Soil
Baermann Funnel method:
Extract live nematodes from soil
Nematodes move out from the soil into the
water,
Then, they will fall to the bottom of the funnel

21. Baermann Funnel Set Up
Soil sample over wire mesh
Funnel
Beaker
Clamp
Rubber tubing
Clamp to hold funnel

22. Put a wire mesh into the funnel. Add a water into
the funnel
A piece of rubber tube is attached to the funnel . A
clamp is used to hold the funnel
Put a beaker below the rubber tube
Add soil sample into the porous paper
Place the sample onto the funnel. Cover the tissue
over the soil
Incubate for 48 hours and collect the nematodes
The nematodes moves actively from the porous paper
into the water and sink at the bottom of rubber
tubing.