Download thrips, mites and mealybugs in grapes

RLO: 2
Title
Identification, Symptoms and nature of damage: Thrips, Mites and Mealy Bug
Learning Objective
To study about identification, Symptoms and nature of damage of thrips, mites and mealybugs in grapes
Introduction
•
Grape (Vitis vinifera) is one of the important fruit crops of India used for table purpose,
resin and wine making with good medicinal value due to the presence of large amount of
antioxidants.
•
Insect pests are the important production constraints in grape cultivation apart from
diseases.
•
In grape, 85 species of insect pests have been reported in India (Atwal and Dhaliwal,
2005) and 94 insect pests have been reported by Tandon and Verghese (1994).
•
Among them, thrips, mites and mealybugs are important sucking pests causes serious
damage to the vineyards.
Thrips
•
Three species namely Scirtothrips dorsalis, Thrips hawaiiensis and Rhipiphorothrips
cruentatus are found causing damage to grapevine.
•
Nymphs and adults pose an increasing threat to grape cultivation by causing scab
formation on berries and resulting in heavy loss in the vineyards.
Identification
•
Adults are very small, elongated and fast moving measuring 2 mm in length with four
narrow fringed wings and live for about 10 days.
•
Eggs are inserted in the tender tissue on the underside of the leaves.
•
Hatching takes place in 8-10 days.
•
After feeding, nymphs move down to the soil and pupate in the top 8-18 cm.
•
Nymphs are similar to adults but are without wings.
•
Total life cycle is completed in about 15 days.
Mites
•
Mites are in the order Acari within the class Arachnida, and are therefore closely related
to spiders.
•
Six species viz., Tetranychus urticae, T. cinnabarinus, T. neocoledonicus, Oligonicus
mangiferus, O. punicae and Eutetranychus orientalis are found causing damage to
grapevine in India.
•
Among them, the two spotted red spider mite T. urticae causes severe loss in
Maharahtara and Andhra Pradesh.
Identification
•
Mites can be distinguished from insects as they possess two distinct body segments, no
antennae and usually four pairs of legs.
•
Developing mites pass through egg, larval, protonymph and deutonymph stages.
•
Female mites lay eggs singly on the under surface of leaves, particularly along the midrib
and veins.
•
Freshly laid eggs are minute, white, spherical and transparent.
•
The newly hatched translucent larva has six legs, while protonymph and deutonymphal
stage has eight legs.
•
Adult spider mite females are reddish in colour and live for about 15 days.
•
Life cycle completes in 10-14 days depending on weather conditions. Breeding is rapid in
summer months.
Nature of damage
•
Both nymphs and adults suck the cell sap from lower surface of tender leaves causing the
cells to collapse and die.
•
In heavy infestations, the mites remove chlorophyll up to 70% leading into development
of brown burnt patches on the infested leaves, which wither and finally dry.
•
Discoloration of leaves leads to reduction in photosynthesis thereby affecting the vigour
of the plants.
•
Severe infestation of spider mites results in delay in maturing and ripening of bunches
and reduction in sugar content thereby affecting the quality of grapes.
Mealybug
•
Among the mealybug species infesting grapes in India, the pink mealybug,
Maconellicoccus hirsutus and the citrus mealybug, Planococcus citri are found causing
severe loss.
•
Mealybug attack weakens the grownup vines. In case of severe mealybug infestation
young vines often die.
•
The grape mealybug causes losses up to 100 per cent in severe cases in the vineyard.
Identification
•
The adult female mealybugs are pinkish (M. hirsutus) or yellowish white (P. citri) and
sparsely covered with white wax.
•
Each female mealybug deposits 350-500 eggs in a loose cottony terminal ovisac during a
week's time.
•
The first instar nymphs are also called as crawlers, which are mobile. They settle on the
plants, start sucking the sap and form the colonies.
•
The total nymphal period vary from 12 - 19 days.
•
Mealybug completes life cycle in about 30 days.
•
Without mating, they are known to reproduce partheno-genetically throughout the year.
Nature of damage
•
Nymphs and adults suck the sap from the trunk, buds, leaves, shoots, nodes, flower
panicles and bunches.
•
Infestation of the growing point especially with the pink mealybug results in
malformation of leaves and shoots tips.
•
Honeydew excreted by mealybug nymphs and adults, supports the growth of sooty mould
on leaves, shoots and bunches.
•
Sooty and sticky bunches harbouring mealybugs and their white cottony wax masses are
unfit for marketing as table grapes.
•
Raisins cannot be prepared from such infested bunches.
MANAGEMENT
•
Removal of weeds and alternate host plants harbouring the mealybugs in and around the
vineyards throughout the year.
•
Install 4-5 yellow sticky coloured traps per acre to monitor thrips population.
•
Deep ploughing in summer or raking of soil in vineyards helps to destroy its pupal stages
and minimizing the incidence.
•
Removal of weeds and alternate host plants harbouring the mealybugs in and around the
vineyards throughout the year.
•
Proper irrigation scheduling reduces the water stress and also increases the humidity
thereby reducing the mite population
•
Releasing the Australian ladybird beetle (Cryptolaemus montrouzieri) @ 5000/ha. in
August- September to clear the mealybug population present on the plants.
•
Swabbing/washing of trunk and cordons with 2 mL of dichlorvos 76 EC + 2 g of fish oil
rosin soap in a litre of water in April-May reduces mealybugs.
•
Neem formulations (EC based) depending upon the strength of botanical viz., 1% @ 2.5
ml and 5% @ 0.5 ml/l can be sprayed @ 400 litre spray solution per acre.
•
Alternatively, two to three foliar sprays of Verticillium lecanii /Beauveria bassiana
(2x108 cfu/ml/g) @ 5 g/Llat 15 days interval can be given.
•
Spray any of the following chemicals viz., Dimethoate 30 EC @ 1 ml/l or Thiamethoxam
25 WG @ 0.25 g/l or Spinosad 45 SC @0.25 ml/l against thrips.
•
Foliar spray of any of the following chemicals is recommendedf or mealybug control.
Buprofezin 25 SC@ 1.25 ml/l or Methomyl 40 SP@ 1 g/l or Chlorpyriphos 20 EC 2
ml/l.
•
Spray any following recommended chemiclas to control mites.
Dicofol 18.5 EC @2.50 ml/l or Fenpyroximate 5 SC @ 1 ml/l or Sulphur 80 WP @ 2
gm/l.
Evaluate yourself:
Questions:
Question 1 of 7
Thrips has fringed wings
True
False
Question 2 of 7
Scab formation in grapes is due to
Thrips
Mites
Stem borer
Mealybugs
Question 3 of 7
Mite posses a pair of antennae
True
False
Question 4 of 7
How many pair of legs adult mite posses
1
2
3
4
Question 5 of 7
First instars of mealybugs are called as
Larva
Crawlers
Maggots
Pupa
Question 6 of 7
Ladybird beetle is of origin from
Australia
India
South America
Canada
Question 7 of 7
Choose the correct answer
Thrips Scirtothrips dorsalis
Red spider mite Tetranychus urticae
Pink mealybug Maconellicoccus hirsutus
Australian ladybird beetle Cryptolaemus montrouzier
LET’S SUM UP
•
Thrips, mites and mealybugs are important sucking pests of grapes causes serious
damage to the vineyards.
•
Thrips pose an increasing threat to grape cultivation by causing scab formation on berries
and resulting in heavy loss in the vineyards.
•
Severe infestation of spider mites results in delay in maturing and ripening of bunches
and reduction in sugar content thereby affecting the quality of grapes.
•
Mealybug attack weakens the grownup vines. In case of severe mealybug infestation
young vines often die.
•
Regular monitoring is necessary to detect early infestations of sucking pests and also to
implement proper control measures.
References:

Sunitha, N, D. and Jagginavar, S, B. (2010). Studies on bioefficacy of neonicotinoids
against grape thrips. Karnataka J. Agric. Sci., 23(1): (163-164)

http://www. nrcgrapes. nic.in

http://www. nhb.gov.in/fruits/grape/gra008.pdf
Evaluate Yourself:
Answer:
Question 1 of 7
Thrips has fringed wings
True
False
Question 2 of 7
Scab formation in grapes is due to
Thrips
Mites
Stem borer
Mealybugs
Question 3 of 7
Mite posses a pair of antennae
True
False
Question 4 of 7
How many pair of legs adult mite posses
1
2
3
4
Question 5 of 7
First instars of mealybugs are called as
Larva
Crawlers
Maggots
Pupa
Question 6 of 7
Ladybird beetle is of origin from
Australia
India
South America
Canada
Question 7 of 7
Choose the correct answer
Thrips Scirtothrips dorsalis
Red spider mite Tetranychus urticae
Pink mealybug Maconellicoccus hirsutus
Australian ladybird beetle Cryptolaemus montrouzieri