Insect Pests of Fruit, Plantation, Medicinal & Aromatic Crops (2+1)

6. Mealy bug - Maconellicoccus hirsutus Green. (Pseudococcidae: Hemiptera )

Damage

• Mealy bugs found on leaves, shoots, nodes, bunch and loose bark of grapevine.
• Infestations of the growing point with mealy bug results in malformation of leaves and shoot tips.
• The greatest damage is done to the fruit bunches. Honey dew secreted by mealy bug nymphs and adults, support the growth of sooty mould on leaves, shoots and branches, sooty and sticky bunches harbouring mealy bugs and their white cottony wax masses tend to be inferior in the market value as table grapes.
• Raisin cannot be prepared from such bunches.
• The quality of the wine is affected.
• In case of severe infestation in the nursery, young vines are often killed.
• The yield loss by mealy bug alone is ranging from 50-100 % in the field.





Bionomics

• The adult females are pinkish and sparsely covered with white wax.
• Each female deposits from 350-500 eggs in a loose cottony terminal ovisac during a week's time.
• The eggs are orange in colour. The egg period is 5-10 days.
• The crawlers are also orange in colour.
• The females have three, while males have four nymphal instars.
• A generation is usually completed in a month but extended in winter months.
Management

• Debark the vines and swab with methyl parathion to minimize the population.
• Apply sticky substances viz., tack-trap or bird tangle foot on the shoot bearing the fruit bunch at a length of 5 cm to keep the bunches free from infestation.
• Release exotic predator Cryptolaemus montrouzieri Muls. in grape vine garden @ 1000-1500 beetles per acre (a single predator consumes 900-1500 mealy bug eggs or 300 nymphs in its development)
• Combine the release of predator and spraying of insecticides dichlorovos (0.20 %) or chlorpyriphos (0.05 %) since they are non toxic to Cryptolaemus.
• Apply granular insecticide aldicarb @ 50 g per vine or phorate 10G @20 gm per vine around the base of the plant.
• Avoid the spraying of insecticides viz., malathion, carbaryl, diazinon, dimethoate, monocrotophos, methyl demeton, phasalone, quinolphos, fenitrothion, methyl parathion since they are highly toxic to the predator.