PHYTOPHAGOUS NEMATODES
Potato
Golden nematode
v
Two
species commonly called "golden nematode" produce cysts on potato
roots: Globodera rostochiensis (the
actual 'golden nematode') and Globodera
pallida (the pale cyst nematode).
v
Plants
are stunted and yellow, and may die off completely, usually in patches in the
field. Potato tubers from affected plants are usually small, but show no other
symptoms.
MITES
Rice Mite:Oligonychus oryzae :Tetranychidae : Acarina
v White spots on lower
surface of leaves which coalesce leading to development of white or silvery
patches
v Nymph and male mite
are yellowish green. Female is green.
Sorghum
Mite: Oligonychus indicus:Tetranychidae: Acarina
v Nymph and male mite
are yellowish green. Female is green. Nymphs and adults spin fine webs and Live
in colonies.
v Suck the sap from
leaves and cause reddish patches. Entire leaf turns into red.
v Improper ear heads.
Red
spider mite:Tetranychus cinnabarinus: Tetranychidae: Acarina
v Host: cotton,
castor, pulses, groundnut, daincha, sesbania, brinjal, tomato, bhendi,
cucurbits, tapioca, beans, grapevine, guava, onion, papaya, sweet orange, rose,
jasmine, marigold and jute.
v Eggs:
Deposit
their eggs on young foliage. Adult:
Generally found on the lower leaf surface. Mite is oval-shaped and dark-coloured
v Spider mites cause
yellow or white spots on the upper surface of the leaflets. Heavy infestation
results in bronzing of the leaves, followed by defoliation.
Tea
Mites : Nymphs and adults infest
upper surface of mature leaves. Infestation starts along midrib and veins and
gradually spreads to the entire upper surface of leaves. Affected leaves become
bronzed, dry and crumpled.
Red
spider mite, Oligonychus coffeae Tetranychidae
Acarina
v Adult female is elliptical in
shape, bright crimson red anteriorly and dark purplish brown posteriorly. O.
coffeae is the largest of all tea mites.
Scarlet
mite, Brevipalpus
californicus Tenuipalpidae:
Acarina
v Adult mite is scarlet red in colour and ovate in shape. They are
slightly bigger than eriophyid mites and can be seen with the naked eye.
Purple mite, Calacarus carinatus Eriophyidae Acarina
v Adult mites are very small and spindle shaped dark purple in colour with
five longitudinal white waxy ridges on the dorsal side.
Pink or orange mite, Acaphylla theae Eriophyidae Acarina
v Adult is very minute, orange coloured and carrot shaped.
Yellow mite, Polyphagotarsonemus
latus Tarsonemidae – Acarina
v They are polyphagous species attacking tomato, cinchona, cotton, pulses,
potato etc. They are seen on young leaves especially the top two to three
leaves and the bud on both leaf surfaces, but more on the lower side.
Eriophyid
mite :Aceria cajani Eriophyidae: Acarina
v
Eriophyid mite: light-colored, long
and spindle-shaped
v The eriophyid mite
is the vector of the pigeon pea sterility mosaic disease.
Coconut
Eriophyid mite, Aceria
guerreronis
v This mite was first reported at Guerrero State in
Mexico in 1965.
v In India first reported at Ernakulamdistrict of
Kerala and Pollachi Taluk of Tamil Nadu in 1998.
v Distribution
:Andhra Pradesh, Karnataka, Kerala,LakshadweepIslands and Tamil Nadu and all the major
coconut growing States
v Total life cycle : 7-9 daysEgg period : 2.5 -4
days. Protonymph : 2 -3 days Deutonymph : 2 -3 daysAdult mite : length
200-250μ: width 36-52 μ.
v
Infestation
usually starts 50 days after anthesis. Spreading of mites mostly occurred
through the wind. Spreading of this mite has also taken place through the
mechanical transfer of the affected nuts from one place to another.
v
The
mites infest and develop on the meristematic tissues of the growing nuts under
the perianth by desapping the soft tissues of the buttons.
v
In
the damaged buttons/nuts, initial symptoms will be in the form as triangular
pale white or yellow patches close to each perianth.
v
Different stages of mites live in the white,
tender portion covered by the inner bracts of the perianth and suck the sap
continuously.
v
When
the feeding activity is enhanced due to increased population build up, it
results in physical damage to the newly formed tissues that become necrotic.
Intensive damage leads to the formation of brown coloured patches later on.
v
In
addition, as the nut grows in size, longitudinal tissues and splits occur on
the outer surface of the husk.
v
Occasionally,
brownish gummy exudates are seen oozing out from the affected surface. Severe
infestation results in poor growth reduced size and copra content and malformed
nuts with cracks and hardened husk.
Jasmine
eriophyid mite, Aceria jasmini Eriophyidae -Acarina
v
Female
is cylindrical and vermiform with two pair of legs and measures about 150- 160
µ long and 44µ thick.
v
Feeding causes felt-like hairy out growth (Erineum) on the surface of leaves, tender stem and flower buds.
Growth of the plant is stunted and flower production is affected.
Chillies
muranai mite Polyphagotarsonemus
latus :Tarsonemidae: Acarina).
v
Mites
are also called as yellow mite, yellow tea mite or white mite.
v
Adult: Mites are minute
(0.2-0.4 mm) and do not form webs. Body is broad, faint-yellow or white in
colour. They are spread by wind, phoretic insects and through contact with
plant surface
v
Responsible
for murda disease. Damage is usually severe in summer months, which coincides
with flowering season.
v
Nymphs
and adults desap in large numbers from the undersurface of leaves, near veins
and vein lets. Infested tender leaves become narrow, lean and lanky with
lateral downward folding, turn pale, undersized, and become cluster at tip of
branches.
v
Petioles
of the lower leaves become extremely elongated with narrow lamina and exhibits
“rat-tail” symptom.
v
Leaves
turn rough and brittle and hence called as murda disease.
v
Infested
plants are stunted.
v
Buds
become distorted or turn phylloid (leafy), dropped. Plants are with poor pod
set and undersized pods.
