Insect Pests of Vegetable, Ornamental and Spice Crops (2+1)

Phytophagous mites

6. Phytophagous mites, Tetranychus urticae (Tetranychidae: Acarina)

Damage:

• Caused by the larvae, nymphs and adults by sucking the cell sap from under side of leaves, flower buds and flowers.
• When population is high it results in bronzing and curling of leaves and discoloration of flowers and leaves.
• Webbing of leaves, sepals and petals occur which give untidy look to the plant.
• The infestation is more severe under poly house conditions.

Identification:

Life cycle:

• Eggs hatch is about 2-4 days
• Newly emerged larva becomes protonymphs in about 2 days
• Protonymph stage is 2-3 days
• Deutonymph stage lasts for 1-3 days
• Male longevity is 9-13 days and females live for 14-20 days.

Salient features:

• Eggs are laid mostly along the midrib and side margins on the lower surface of the leaves.
• Weather factors play an important role
• Under dry and hot conditions the multiplication of these mites is very high and the infestation is also severe.
• High humidity and temperature reduces the reproduction of the pest and hence the incidence is low.

Management:

• Remove the old and infested leaves and burn them
• Try to avoid dry conditions and spray frequently with plain water at least twice a week with sprinkler.
• Observe the plants regularly for mite population and if incidence is noticed spray the crop with insecticides like or profenofos (0.05%) or fenazaquin (0.0025%) or propargite (0.057%)