Plant Diseases Spread by

Mites
Mites –Importance, morphology and biology
Class: Arachnida
Order: Acarina
Importance of Mites
• loss to a variety of agricultural and horticultural crops particularly under dry
situations
Phytophagous mites:
1. Eriophyidae (Erenium or gall or itch or rust mites)
2. Tetranychidae (spider mites)
3. Tenuipalpidae (Broad mites)
4. Tarsonemidae (False spider mites)
• vectors of important viral diseases
Aceria cajani- redgram sterility mosaic disease
Aceria tulipae- wheat streak mosaic diseases
• Allergies in human beings Eg. House Dust Mite: Dermatophagoides farina
• loss to the stored produce Eg. Stored grain mite: Acarus siro
• honeybees parasites
Ecto Parasite: Tropilaelaps clariae, Varroa jacobsoni
Endo Parasite: Acarapis woodi(Tarsonemidae)
Locustacarus buchneri ( Poapolidae) on bumble bees
• (predatory mites) very useful in biological control of some
insect pestsPhytoseilus
Phytoseiidae- and mites persimilis, Amblyseius fallacies
MORPHOLOGY:

• Vermiform, divided into cephalothorax and abdomen with 2 pairs of legs in family Eriophyidae

• In Tetranychidae, body is divided into Gnathosoma and Idiosoma

• Gnathosoma contains 3 segments with mouth parts like Chelicerae on 2nd and Pedipalpi 3rd segments

• Above the mouth cavity there is a capitulum or tectum dorsally

• Idiosoma is further divided into Podosoma and Opisthosoma

• Podosoma further divided into Propodosoma and Metapodosoma with 2 pairs of legs on each

• Opisthosoma is the posterior part of the body having anal opening

• Eyes may be present or if eyes are absent body surface act as photo sensitive organ

• Chelicerae , 3 segmented, modified into stylet like piercing organs

• Pedipalpi are resembling the legs and are modified as piercing or grasping organs

• Legs may be 2 or 4 pairs

• Each leg consists of coxa, trochanter, femur, Genu, tibia and tarsus
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Family: Tetranychidae( spider mites)
Body is 0.2-0.8 mm long with colour is red, green, yellow, brown etc.
Body is flat, oval and neither divided nor segmented
Body of male tapers posteriorly
Chelicerae are fused to form a stylopore
movable segment forms a flagellate stylet
no mitotic division in larval stage
Most of the species are having narrow host range
Palpal thumb claws are present
Life cycle includes
Egg-Larva (3 pairs of legs)-Protonymph (4 pairs of legs)
Deutonymph( 4 pairs of legs)-Tritonymph( 4 pairs of legs) and Adults ( 4 pairs of legs)
Examples:
1. Red spider mite on okra, cotton, citrus, tomato, grape, papaya, jasmine, pumpkin Tetranychus macfarlani( telarius)
results in Browning of leaves, fruits and hairy out growth on both.
2. Jowar mite ( greyish green): Oligonychus indicus, lower side of leaf becomes wet, red spots appear in patches on
leaf
3. Vegetable mite, Tetranychus cucurbitae
Family:Tenuipalpidae (false spider mites)
• Same as Tetranychidae, but without thumb claws
• Three types of setae namely hysterosomal, dorsocentral and mediolateral are
• present
True tarsal claw is hooked or pad like and with tenent hairs
Examples: Citrus flat mite- Brevipalpus lewisi
Brevipalpus californicus- It causes serious injury to a wide variety of ornamental and agricultural
crops
Family: Tarsonemidae (Broad mites)
• Body is elliptical ( ovoid) and 0.1-0.3 mm long and colour is opaque white, light green, pinkish
• three parts Capitulum, Propodosoma and Prohysterosoma (the later two parts together known as
• Idiosoma)
• Mouth parts are contained in a distinct capsular head known as Capitulum
• Females are bigger than males and adult integument is hard and shiny
• Few hairs, spines are present on body
• Chelicerae are needle like
Egg – larvae – adult
Examples: Yellow mite on chilli- Palyphagotarsonymus latus
Paddy panicle mite - Stenotarsonemus spinki
Family: Eriophyidae (Blister, rust, gall mites)
• Body is minute measuring 0.08 – 0.2 mm long
• Body is 2 types:
a) Elongate ( vermiform), worm like, soft body
b) Wedge shaped, hard body
• Body is divided into cephalothorax and tapering abdomen
• Abdomen is finely striated with long setae
• 2 pairs of legs on anterior end of body Pedipalpi or chelicerae independently and form a telescope or fold base
• move
No thrusting stylopore
Egg-Protonymph-Deuteronymph-Adult (2 pairs of legs in all the life stages)
Examples:
1. Citrus rust mite- Phyllocoptruta oleivora
2. Jasmine mite- Aceria jasmini
3. Mango gall mite- Aceria mangiferae
4. coconut mite- Eriophyes guerreronis

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Nature and symptoms of Mite damage:
• Both nymphs and adults suck sap from plant parts like leaves, shoots, fruits etc with their needle like
chelicerae
1) Formation of white blotches on leaves in vegetables

2) Characteristic red spots that enlarge and coalese making whole leaf reddish

3) Drying of leaves and stems in sugarcane

4) Formation of galls on leaves in pongamia

5) Production of felt like growth on leaves in jasmine

6) Formation of crowded buds ,crumpled shoots in mango

7) Formation of pinkish blotches on fruits of citrus

8) Curling of leaves upwards in chillies

9) Formation of warts and longitudinal tissues on coconut

10) Act as vectors by transmitting viral diseases

11) Spin delicate webs on the lower surface of the leaf

 Plant Viral Diseases
Vectored by Eriophyid Mites
• Wheat Streak Mosaic
Virus (WSMV)
• Wheat Spot Mosaic
Virus (WSpMV)
• Ryegrass Mosaic Virus
(RgMV)
• Agropyron Mosaic Virus
(AMV)
• Currant Reversion Disease
• Pigeon Pea Sterility Mosaic
Disease (PPSMV)
• Rose Rosette Disease (RRD)
• Fig Mosaic Virus (FMV)
• Peach Mosaic
• Cherry Mottle Leaf
Virus (CMLV)
 Plant Viral Diseases
Vectored by False Spider
Mites
• Citrus Leprosis
• Passion Fruit Green Spot
Virus (PGSV)
• Coffee Ring Spot Virus
(CoRSV)
• Orchid Fleck Virus (OFV)
 Diseases Transmitted by Mites

Wheat Streak Mosaic Virus (WSMV)

• WSMV is a seed and mite-borne virus that infects wheat causing severe leaf symptoms
and reduced yields
• The wheat curl mite (WCM), Aceria tosichella, vectors this virus
• Leaf curling and the occasional trapping of the flag leaf.
• Under ideal conditions a single female lays 12–20 eggs.
• Completes its life cycle in 8–10 days
• Peak mite population is found at approximately 25 °C but its
• development is reduced at 30 °C and below 15 °C. WCM is capable of surviving for
• a few months in cold conditions but reproduction is significantly lowered
• Both nymphs and adults of WCM transmit wheat streak mosaic virus
• For a mite to become viruliferous, the virus must be acquired during the two nymphal
• stages, typically after at least 15–30 min of feeding on infected plant material.
• Once infected the mite has the potential to transmit the virus to noninfected plants for at
least 7 days.
Management of Wheat Streak Mosaic Virus (WSMV)
• Serious outbreaks of WSMV can only occur if the mite vector is abundant and a source of
WSMV is present.
• The management of the disease is highly dependent on controlling WCM populations and
sources of WSMV.
Following control options against WSMV should be followed:
• Control the ‘green bridge’ (volunteer crop cereals, e.g. wheat, barley, cereal rye, oats and
grassy weeds) as these hosts harbour both WSMV and WCM. So their control needs to be
done throughout the paddock (including along the fence line) at least one month before
sowing wheat.
• Sow healthy seed stocks of wheat.
• Avoid early sowing in virus risk conditions.
• Break the disease cycle by controlling over-summering volunteer wheat/cereals and
grasses within the field, on field boundaries and road sides, reducing the mite populations
invading autumn sown crops.
• Whenever it is possible, delay sowing of wheat in autumn until temperatures are too low
for mite activity.
Plant Fungal Diseases Vectored by Eriophyid Mites
Mango Malformation Disease (MMD)
 Plant Fungal Diseases Vectored by Eriophyid Mites

Mango Malformation Disease (MMD)

Long bud mite, Aceria mangiferae, has been reported to be associated with the mango malformation disease
Caused by the fungal pathogen, Fusarium moniliforme var. subglutinans
A. mangiferae is found mostly on apical growing buds rather than on the lateral dormant
buds.
Within the buds, A. mangiferae are found in peripheral scales than in the meristematic
dome within the apical bud.
The upper and middle canopy of the tree reported are more preferred than the lower
canopy by mites.
The mite is reported commonly on buds and inflorescences of the mango.
The main spread of MMD to new areas is by infected pruning equipment or vegetative
planting material
 Plant Viral Diseases Vectored by False Spider Mites

Citrus Leprosis

Caused by two viruses, namely, cytoplasmic type (CiLV-C) and nuclear type (CiLV-N).
Tenuipalpid mite, Brevipalpus phoenicis, has been reported as the vector
The virus in B. phoenicis is transmitted transtadially but not transovarially
Symptoms:
Chlorotic lesions on the fruit and leaves that do not result in systemic infections
Premature fruit drop, defoliations and death of the twigs can occur with devastating
results.
Death of a twig or branch results when they become girdled by individual lesions
If the mite vector is not controlled, CiLV-C can kill a tree within 3 years
Plant Viral
Diseases
Vectored by
Spider Mites
(Tetranychidae)
Barley yellow streak
mosaic virus (BaYSMV)
Barley yellow streak mosaic virus (BaYSMV)

• Brown wheat mite (Petrobia latens) has been observed as a vector of BaYSMV
• BaYSMV disease outbreaks are associated with recurring drought and are accompanied
by infestations of BWM which is found under drought conditions.

• Early symptoms of streak mosaic virus disease resemble the feeding damage of non-
viruliferous mites. Diseased barley and wheat leaves appear light green to pale yellow.
• As the disease progresses, the leaves acquire light green to yellow dashes and streaks.
• In addition some leaves display a uniquely diagnostic symptom pattern of yellow
• banding wherein a wide band parallel to the mid-vein on one half of the leaf is
discoloured, whereas the other half is a symptomatic dark green.
• Most infected plants exhibit moderate to severe diversing.
• Brown streaks appear on the leaves; in some cases the extremely diseased plants die
 Management of Mite-
Vectored Plant Viral
Diseases

• Genetic host resistance

• Resistant type of plants should be planted whenever
they are available. Recent advances in plant cell
molecular biology and virology have lead to the
development of genetically modified plants with
superior resistance to some viruses
Management of
Mite-Vectored
Plant
Viral Diseases
• Cultural practices
• Scouting and removal
• Encourage rotation to
non-host crops
• Sanitize tool
• Heat therapy

This Photo by Unknown author is licensed under CC BY-SA.

Control
• Chemical applications.
• As such there are no chemical sprays or biological control approaches to
eradicate viruses, although such approaches can be used to control mite vectors.
• Regulatory measures.
• Management of mite vector populations in the field can be difficult or impossible
unless coordinated on a regional basis, but may be highly effective in closed
production systems such as greenhouses.
Management of mites:

1. Removal of alternate hosts in the field

2. Spraying of sulphur @ 3 gm or Dimethoate 30 EC @ 2 ml/lt or

Methyldemeton 25 EC @ 2 ml /lt or kelthane (Dicofol) 5 ml /lt or Ethion @ 1 ml/lt

3. Fungal pathogen, Hirsutella thompsoni reported to be effective against coconut eriophid mite

4. Predaceous insects on mites Ex. Scolothrips indicus, Scymnus gracilis

Acaricides: Most of the organophosphatic insecticides are also effective acaricides

i) Sulphur: fine dust (80–90%), FLOWABILITY of the dust is increased by adding 3% tricalcium phosphate

ii) Dicofol: hydroxylated product of DDT, It is non-systemic, effective against all stages of mites Trade names: Kelthane

iii) Tetradifon: Persistent acaricide, kills all stages of mites except adults Trade names: Tedion

iv) Propargite: It is non-systemic acaricide, used for control of mites on fruits, grain, vegetables, nut and crops

Trade names: Comite, Omite

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