I. Introduction
Nematodes are the most numerous multicellular
animals on earth. A handful of soil will contain thousands of the microscopic
worms, many of them parasites of insects, plants or animals. Free-living
species are abundant, including nematodes that feed on bacteria, fungi, and
other nematodes, yet the vast majority of species encountered are poorly
understood biologically. There are nearly 20,000 .described species classified
in the phylum nematode.
Nematodes are structurally simple organisms. Adult
nematodes are comprised of approximately 1,000 somatic cells, and potentially
hundreds of cells associated with the reproductive system. Nematodes have been
characterized as a tube within a tube; referring to the alimentary canal which
extends from the mouth on the anterior end, to the anus located near the tail.
Nematodes possess digestive, nervous, excretory, and reproductive systems, but
lack a discrete circulatory or respiratory system. In size they range from 0.3
mm to over 8 meters.
Maybe we ever or often find many plant which
indicated existence of stricken with disease. For example leaf the color is
yellow or to twist, the root broke or short, the plant sometimes even be dead.
The condition indicated sign symptoms of plant parasitic nematode. The plant
parasitic nematode indicated there are many kinds. But most people don’t know
about it. Therefore, in this paper will be discussion what is nematode? What
characteristic of nematode? How many kinds of plant parasitic nematode? What
symptoms of plant parasitic nematode damage?
II. Contain
Nematodes are tiny, round-bodied, unsegmented,
worms. Most yards typically have billions of them in the soil, feeding on
organic matter, bacteria, insects and plants. Approximately 10% of all
nematodes feed on plants, living around or in the roots. The most well known is
the root knot nematode (Meloidogyne spp.), because of the distinctive galls it
causes on infected roots, it's wide distribution, and the wide range of plants
that it attacks (including most common vegetables, ornamentals, and fruit
trees.).
Nematodes live in the sea, in fresh water, and in
soil. Nematodes have been discovered on the very highest mountain tops,
and in the greatest depths of the
oceans. Scientists estimate that good top soil will contain billions of
nematodes per hectare. But nematodes are also pests. They parasitise almost
every species of animal and many plants, indeed nematode infestations can be so
devastating that they are one of the most important of all the world's
parasitic animal groups.
Nematodes are worm-shaped microorganisms,
bilaterally symmetrical body shape, and species that are parasites on plants,
very small size that is between 300 - 1000 microns, up to 4 mm in length and
width 15-35 microns. Due to the very small size is causing these nematodes can
not be seen with the naked eye, but can only be seen with a microscope.
The characteristics of nematodes include:
·
A
body that is bilaterally symmetrical or cylindrical in shape;
·
A
body covered with a secreted, flexible, non-living cuticle, similar to the
material from which our fingernails are made;
·
Moveable
cilia and flagella are completely lacking; and
·
Muscles
in the body wall run in a longitudinal direction only.
There are a few other things that make nematodes
special. Most are under 5 cm long, and many are microscopic. Some of the
parasitic nematodes may be over 1 m in length.
A. Ways
nematodes Attack and Its Effect on Plant Roots
Nematodes that attack plant roots can lead to
mechanical damage . Nematodes that cause damage to crops almost entirely live
in the soil , either free-living in the soil outside the roots and stems in the
soil even some parasites whose lives are lived in the roots and stems . Greater
concentration of nematodes live in the roots of host plants are mainly due to a
faster rate of reproduction due to the availability of adequate food and
attraction of nematodes by substances released in the rhizosphere initially ,
nematode eggs are placed in the root - plant roots in the soil and eggs will
develop into larvae and adult nematodes . Gathering nematode populations around
the root nematodes attack the roots by pushing the cell walls poking . Adult
nematodes are constantly moving every second , every hour , every day and
settle around the roots , the movement - the movement of nematodes bite and
inject saliva on the plant roots , causing the plant cells become damaged .
Symptoms of root damage caused by bites of nematodes characterized by root knot
( gall ) . Luka root , root tip was broken and the roots will rot if the
nematode infection is accompanied by bacterial and fungal pathogens . Symptoms
of damage to the roots is usually always followed by slow growth due to inhibition
of nutrient uptake by roots that eventually happens nutrient deficiency such as
leaf yellowing , wilting on the weather dry and hot , so that the productivity
and quantity of crop yields declined even to certain plants resulted in plants
can not be harvested at all ( puso ) , declining and poor quality .
There are three main types of plant parasitic
nematodes based on feeding habit, they are; ectoparasitic, endoparasitic and
semi-endoparasitic.
1.
Ectoparasitic–
entire body outside the root
The first feeding type is the ectoparasitic mode, in
which the nematode remains outside of the plant and uses its stylet to feed
from the cells of the plant roots. Nematodes that use this strategy can graze
on numerous plants, making it easier for them to switch hosts, but their added
mobility makes them very susceptible to environmental fluctuations and
predators. Ectoparasitic nematodes can have extremely long stylets, which
assist them in feeding deep within the plant root on nutrient rich plant cells.
Some of these nematodes induce the plant to form an enlarged cell that the
nematode feeds from for an extended period of time. Note, in all life cycle diagrams in this
article the abbreviation J=juvenile and the number refers to the stage of the
nematode and M=molt and refers to how many molts the nematode has completed.
The above life cycle is typical for a nematode in
the class Enoplea, but most nematodes in the class Chromadorea undergo their
first molt in the egg and hatch as J2. All motile nematode stages are capable
of feeding from the plant. The nematodes feed, undergo four molts into adults,
mate and lay eggs. Some nematodes that use this feeding strategy can form
terminal galls in the roots and cause severe stunting of the root system. An
example of an ectoparasite is Xiphinema (dagger nematode), shown below, feeding
from a fig root. This enoplean nematode is particularly problematic because it
can harbor and transmit plant viruses. Only ectoparasitic nematodes in the
class Enoplea transmit viruses, but because of the virus transmission, this
type of nematode in low numbers can still be very damaging to plants.
2.
Endoparasitic–
entire body inside the root
Endoparasitic
nematodes spend part of all of their life cycle within the plant. These
include: cyst, root knot, lesion, and stem and bulb nematodes. Soil samples
take at the root level will usually reflect populations of even endoparasitic
nematodes through larval populations, which have not yet entered the plant root
system.
3.
Semi-endoparasitic-
part of body inside root
Nematodes
that feed as semi-endoparasites are able to partially penetrate the plant and
feed at some point in their life cycle. Usually the head of the nematode
penetrates into the root and allows the nematode to form a permanent feeding
cell. These nematodes swell and do not move once they have entered into the
endoparasitic phase of their life cycle. By giving up their mobility, the
nematodes risk death if their host plant dies, but they also benefit from
forming a permanent feed site, which increases their nutrient uptake and
reproductive potential. A typical nematode with this life cycle is
Rotylenchulus reniformis, the reniform (kidney-shaped) nematode. This nematode
hatches from the egg as a J2, then quickly molts in the soil to the adult stage
without feeding. The anterior end of an adult female enters the plant root and
forms a feeding cell. After mating, the female lays its eggs outside of the
root in a gelatinous egg mass Maggenti (1981). Another nematode with a similar
feeding strategy is Tylenchulus semipenetrans, the citrus nematode, although
the juvenile stages of this nematode do feed as ectoparasites. As is common in
biological systems, it is often difficult to precisely classify animals due to
variation in their behavior. True to this rule, several species of
ectoparasitic nematodes (e.g. Helicotylenchus) are also capable of partially
penetrating the root and feeding. However, we do not classify these nematodes
as semi-endoparasites because they do not exhibit a consistent endoparasitic
feeding behavior.
B. Symptoms
of Nematode Damage
Symptoms of nematode damage vary greatly with the
type of nematode, the age of the plant, and the plant part that is affected. There
are two kinds of symptoms of nematode damage, they are,
1. Symptoms
of attack above ground
1. Abnormal growth caused by injury to the shoots,
growing point, and primordial interest. :
a) Buds die.
Nematode attack sometimes cause death buds or
growing point of the plant, so the plants can not live. This case occurs in
strawberry plants are attacked by Aphelenchoides.
b) stems and leaves shriveled
Nematodes attack the growing point of the plant,
sometimes cause plants to die and still allows the stems, leaves, or other
structures may evolve. The development of these organs was not perfect, causing
the contraction or twisting. Examples of wheat plants infected larvae Anguina
tritici on regional growth point.
c) Puru seed
Seeds of herbaceous plants or seeds are attacked
Anguina. Once the flower is formed, which has grown nematode perfect start in
and strike at this section until the adult nematodes. This is where developing
States nematodes multiply. As a result of primordial interest to form a knot
that contains a large number of nematode larvae; nematode is able to live in a
long time.
2. Abnormal growth as a result of the wounds on the
inside of the stem and leaves.
a. Necrosis
Several types of nematodes live and eat in the stem
and leaf tissue, resulting in necrosis. Examples of symptoms of the disease
"red ring" on palm stems are attacked by Rhadinaphelenchus
cocophilus, due to injury at the base of the plant stem. Another example,
Ditylenchus dipsaci which cause injury to the stems and leaves of the various
plants.
b. Spotting and leaf injury.
Nematodes that attack the leaves, sometimes eating
and damage the parenchyma tissue. The nematodes enter through the stomata.
Example: Aphelenchoides ritzemabosi that attacks the leaves Chrysantemum.
c. Galls on leaves
Anguina balsamophila and A. millefolii cause galls
on leaves infected by this nematode.
2. Symptoms
of attack under the ground
a. Root
Knot.
(Root Knot)
b. Foul
Nematodes
that enter the plant causing injury. The injury initially caused by nematodes
beak, but more severe damage happens next may be caused by other organisms
incoming attacks as secondary pests. Examples. Symptoms foul by Ditylenchus
destructor on potato tubers.
c. Necrosis
On The Surface
Nematodes
that eat the roots of plants from the outside, it may cause the death of the
cells in the surface tissue. This condition then cause a color change in the
section. When nematode populations that attack are high, it can cause death of
epidermal cells, so that the roots are still young will change color become
yellow to brown. Aphelenchoides example parietinus attack Cladonia fimbriata
(lichens) and Tylenchuluss semipenetrans attack citrus crops
d. Wound
These
symptoms occur when the nematode beak injuries caused small to medium sized.
Example: Radopholus similis on banana roots.
e. Excessive
Root Branching
Presence
of nematodes attack can spur formation small roots around the root tip. Example
Naccobus attack, Trichodorus.
f. Injury
or death of the root tip.
After
the nematodes feed on the roots, resulting in the end will stop its growth, as
well as the cessation of growth of the branches of the root.
It is important to note that knots on roots are not
always associated with nematode damage. Nitrogen fixing nodules appear much
like root knot nematodes on the root. Some plants naturally produce them. It is
also important to note that knots need not be present to have a nematode
problem. If one or more of the above symptoms are present, testing for nematode
damage is indicated.
Meloidogyne incognita, M. javanica, M. arenaria, M.
exigua, (tomat, tebu, kopi, kakao, mbako, kubis)
Parasit nematode in plant commenly : Nematoda Sista
Kentang (NSK), Tylenchulus semipenetrans in orange , Pratylenchus coffeae,
P.pratensis in kakao, Radopholus similis (orange, banana, kakao,etc.), Rotylenchulus
reniformis (kakao, orange,etc.).
Nematodes can damage part of plant, they are in
Alfalfa plant (the root knot, stem, lesion, cyst, pin, stubby-root), in Beans (root
knot, sting, pin, cyst, stubby-root, stunt), Banana (root knot, burrowing,
lesion, lance), Citrus (citrus, burrowing, lesion), Corn (sting, lesion,
stubby-root, lance, cyst), Cotton (root knot, sting, lance), Grapes (root knot,
dagger, sting), Oats (cyst, anguina, lance), Ornamentals (root knot, lesion,
spiral reniform), Potato (root knot, golden nematode), Soybeans (cyst, sting,
root knot, stunt), Tomato (root knot, dagger, sting), Turf (root knot, cyst,
lance, sting, spiral, ring, bentgrass, nematode, stunt, sheath), Wheat (cyst,
anguian, sheath, root knot, pin, stubby-root, stung).
C. Classification
Of Plant Parasitic Nematode
In general phylum nematode classified into three
orders, namely: Order Tylenchida, Dorylaimida Order, and the Order Rhabditida. Plant
parasitic nematodes usually consists of the Order and Dorylaimida Tylenchida
whereas saprophytic nematodes and some types of parasitic insects that act as a
group the Order Rhabditida. Characteristic of order Dorylaimida and Tylenchida
can be seen in the following table:
|
|
||
|
Shaped slim
stylet , tapering, usually at the base of the stylet there is knobs are
composed of three parts as the attachment of muscles.
|
Most have a
short and fat stylet, sloping edges without knob at the stylet base, or at the mouth
toothed. Which is parasitic on plants usually have a long stylet.
|
||
|
Farink divided
into four sections of the front row is prokorpus, metakorpus (a sheet shaped
like a crescent moon, as the attachment of the radial muscles), isthmus
(flat elongated circled by a ring of nerves), and the bottom is the basal
bulb or lobes.
|
Farink not
have a metakorpus. Consists of anterior part and posterior part, where the
posterior is rather wide than anterior
part. Can also be entirely cylindrical.
|
||
|
The cuticle of
nematode group has clear anulasi.
|
Anulasi
cuticle is usually not visible when observed with a light microscope.
|
III. Conclusion
Nematodes are
tiny, round-bodied, unsegmented, worms. Most yards typically have billions of
them in the soil, feeding on organic matter, bacteria, insects and plants.
Approximately 10% of all nematodes feed on plants, living around or in the
roots. The most well known is the root knot nematode (Meloidogyne spp.),
because of the distinctive galls it causes on infected roots, it's wide
distribution, and the wide range of plants that it attacks (including most
common vegetables, ornamentals, and fruit trees).
Nematodes have
characteristic are the body that is bilaterally symmetrical or cylindrical in
shape, body covered with a secreted, flexible, non-living cuticle, similar to
the material from which our fingernails are made, moveable cilia and flagella
are completely lacking, and muscles in the body wall run in a longitudinal
direction only.
There are three
ways nematodes attack the plant, they are ectoparasitic, endoparacitic and
semi-endo parasitic.
There are two
kinds of symptoms of nematode damage, they are symptoms of attack above ground
and symptoms of attack under the ground. Symptoms of attack above the ground
consist of the abnormal growth caused by injury to the shoots, growing point,
and primordial interest (buds die, stems and leaves shriveled, seed knot) and abnormal growth as a
result of the wounds on the inside of the stem and leaves (necrosis, spotting
and leaf injury and galls on leaves). And then symptoms of attack under the
ground consist of root knot, foul, necrosis on the surface, wound, excessive root branching, injury or death of the
root tip.
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Dropkin,
V. H. 1992. Pengantar Nematologi Tumbuhan.
Gadjah Mada University.Yogyakarta.
Inserra,
R. N., L. W. Duncan, D. Dunn, D. Kaplan, and D. Porazinska. 1998. Pratylenchus
pseudocoffeae from Florida and its relationship with P. gutierrezi and
P. coffeae. Nematologica 44:683-712.
Munif,
A. 2003. Prinsip-prinsip Pengelolaa
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