Insect Pests of Vegetable, Tuber and Spice Crops

Crucifer leaf weber

Lecture 7: Crucifer leaf weber

5. Crucifer leaf weber, Crocidolomia binotalis (Pyralidae: Lepidoptera)

Distribution: India, Srilanka, Myanmar.

Host range: Cabbage, cauliflower, raddish, mustard and other cruiferous crops. The pest has also been recorded from Thymus vulgaris (Family: Labiatae)

Nature of damage:

• Damage is caused by the larvae.
• Young larvae are gregarious and feed on chlorophyll
• Older larvae web leaves together and feed on lower surface.
• Up to 80 per cent of the plants may be attacked.
• Capable of destroying premordia and preventing the establishment of young plants

Identification:

Life cycle:

• Eggs hatch in 4-8 days
• Larval stage is 14-24 days in summer and about 50 days in winter.
• Pupal period is 14-40 days
• Total life cycle in 40-80 days.
• Adult longevity is 6-12 days
• More than one generation in a year.

Salient features:

• Moths lay eggs on the under surface of the leaves in masses of 55-75 and each female lays 1-4 egg masses.
• Larvae pass through four to five stages.
• Pupate in soil in earthen cocoons at a depth of 10-20 cm.

Management:

• Remove and destroy webbed leaves having larvae inside.
• Mustard can be used as trap crop
• NSKE @ 4.0 per cent or other neem based insecticides
• Bt formulations @ 500g /ha
• Natural enemies like Apanteles oblique, Apanteles sp, Enicospilus xanthocephalus, Palexorista solennis and Eocanthecona furcellata also take care of the pest in nature
• Need based spraying of crop with malathion(0.05%), methyl demeton(0.025%), chlorpyriphos(0.04%)
• A waiting period of 7 days should be observed.