Insect Pests of Fruits, Plantation, Medicinal & Aromatic Crops

3. Fruit fly - Bactrocera dorsalis Bend. B. zonatus Saund.,B. tau and B. correctus Beezzi. ( Tephritidae : Diptera )

Damage

• The maggot destroy and convert the pulp into a bad smelling, discoloured semi liquid mass unfit for human consumption.
• The infestation results in fruit drop and start rotting from inside.
• On complete rotting of the fruits, the damaged fruit develop yellow spots with black centers through which liquid oozes out on pressing.
Bionomics

• The adult fly is brown or dark brown with hyaline wings and yellow legs.
• The female fly lays eggs in clusters of 2-15 just beneath the skin of the ripening fruits.
• A single female lays up to 200 eggs during oviposition period of one month.
• The egg period is 22-23 days.
• The maggot feeds on pulp and become full grown in about 7 days.
• It pupates 3-7 inches below the soil.
Management

• Plough the interspaces to expose the pupae during the off - season.
• Collect and destroy the fallen fruits.
• Set up fly trap using methyl eugenol. Prepare methyl eugenol 1 ml/ 1 litre of water + 1 ml of Malathion solution. Take 10 ml of this mixture per trap and keep them at 25 different places in one ha between 6 and 8 am. Collect and destroy the adult flies.
• Conserve parasitoids like Optius compensates and Spalangia philippinensis.
• Use bait spray combining molasses or jaggery 10g/1 and one of the insecticides, fenthion 100 EC 1 ml/1, malathion 50 EC 2 ml/1, dimethoate 30 EC 1 ml/1, carbaryl 50 WP 4g/1, two rounds at fortnightly intervals before ripening of the fruits.