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

3. Thrips - Scirtothrips dorsalis Hood. (Thripidae: Thysanotptera)

Damage

• Both nymphs and adults infest the tender leaves causing curling and crinkling of leaves. The crop growth stunted and bronzed, the infested buds and flowers become brittle and drops.
Bionomics

• The insect reproduces asexually as well as parthenogenetically. The female thrips inserts the eggs into the veins of leaves. It lays about 40-50 eggs. The nymphs on hatching crawl on to the tender shoot for feeding. It pupates in sheltered places such as leaf axils, leaf curls and base of flowers and fruits. Egg period is 5 days and larval period is 7-8 days. Pre-pupal period is 18-24 hours and pupal period is 48-56 hours. The total life cycle is completed within 10-15 days.
Management

• Inter-crop with agathi Sesbania grandiflora to provide shade which regulates the thrips population.
• Apply carbofuran granules at 200 g /cent area in the nursery.
• Root dip the chilli seedlings in monocrotophos 0.05 % solution for 20 minutes before transplanting gives protection up to 28 days.
• Apply dust formulation of insecticides early in the morning at 25 kg/ha.
• Spray dimethoate 30 EC 2 ml/ litre or formothion 2 ml/ litre thrice at fortnightly intervals.