Mites,Slug,Snail_Infesting agricultural crops.pdf

Mites
Slugs and Snails
By
Dr. U. Pirithiraj, P.hD.
Assistant Professor (Entomology)
JSACAT
Affiliated to Tamil Nadu Agricultural University

Mites
• Order : Trombidiformes (Acarina) Class : Arachnida
• Mites normally feed on the undersurface of the leaves but
the symptoms are more easily seen on the uppersurface.
• Tetranychids produce blotching (Spots) on the leaf-
surface.
• Tarsonemids and Eriophyids produce distortion (twist),
puckering (Folds) or stunting (Short) of leaves.
• Eriophyids produce distinct galls or blisters (fluid-filled
sac in the outer layer)
Dr. U. Pirithiraj, P.hD. (Entomology)

Family : Tetranychidae
Tetranychus cinnabarinus, T. ludeni, T. urticae
This species has a world-wide distribution. Its
infestation recorded on castor, pulses, groundnut, daincha,
sesbania. Brinjal, cotton and bhendi are the worst sufferers.
Symptom of damage
Undersurface of the leaves get covered with strands
of webbing which affect photosynthesis and so the yield.
Chlorotic spots coalesce into pale or silvery patches.
Growth, flowering and fruit setting in the plants are
greatly affected. Both nymphs and adults cause the damage.
Tetranychus urticae

Oligonychus oryzae
Oligonychus indicus
It is a serious pest of sorghum, maize, sugarcane and some
cereals.
Symptom of damage
White or red patches on the lower surface of leaves of sorghum
and sugarcane. Both nymphs and adults cause the damage.
Oligonychus oryzae
It infests rice. White spots on lower surface of leaves which
coalesce leading to development of white or silvery patches. It is
severe during summer.

Family: Tarsonemidae
Polyphagotarsonemus latus (yellow mite, broad mite,
chilli muranai mite)
These are pests of chilli, cowpea, greengram,
horsegram, sesamum, lablab, jute and cotton.
Symptom of damage
Sudden curling and crinkling of leaves followed by
development of blister patches. Severe stunting of
growth and death of plants.
Polyphagotarsonemus latus

Panicle rice mite, Steneotarsonemus spinki,
Tarsonemidae, Acarina
Mites found in between stem and leaf sheath
Desap the sheath in association with fungus
(Sarocladium oryzae)
Steneotarsonemus spinki

Family Eriophyidae
Aceria cajani
It is a vector of sterility mosaic of
pigeonpea.
Aceria sorghii
Leaf crinkling, general chlorosis
and choking of terminal leaves.
Host plant is sorghum.

Management
• Spray wettable sulphur 50 WP 2g/lit or dicofol 18.5 EC 2.5 ml/lit
• The mite develops resistance within 2–3 years, so repeated use of
acaricides should be avoided to reduce resistance.
• Carbaryl and pyrethroids should not be used as they increase the
pest incidence.
• Sulphur based insecticides must not be used in cucurbits as they
cause phytotoxic effects.

Slugs and Snails
Snails differ from slugs in having a spirally coiled shell over their body
They do a lot of damage to vegetables, garden plants, the damage being more serious
in the seedling stage.
Invertebrata
Phylum: Mollusca
Class: Gasteropoda

Giant African snail - Achantina fulica - damage
plantation crops like arecanut, rubber buds and
coffee
Common garden snails - Macrochlamys indica
Green house snail - Opeas gracilis

Common Indian slugs : Limax sp.,
Laevicaulis alte
Arion sp.

Management
Cultural
• They can be handpicked and killed.
Chemical
• Metaldehyde (5%)
• Copper sulphate solution (1%)

Mites,Slug,Snail_Infesting agricultural crops.pdf

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Mites,Slug,Snail_Infesting agricultural crops.pdf