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

4. Fruit fly

4. Fruit fly - Bactrocera (= Dacus) diversus Coq. ( Tephritidae : Diptera)

Damage

• The maggot bores into the fruits and feeds on soft pulp.
• The infested fruits show small cavities with dark greenish punctures and when cut open, the wriggling maggots are seen inside.
• It infestation causes rotting and dropping of fruits.

Cut open fruit with maggots

Bionomics

• The adult fly is smoky brown with greenish black thorax having yellow marking.
• It is active throughout the year except severe cooler months.
• It lays the eggs on the soft skin offruits. The egg period is 1-4 days during July.
• The maggot is pale cream in colour, cylindrical in shape measuring 5-8 mm in length.
• The larval stage lasts for 4-5 days. It pupates in soil.
• The pupal period extends from 7 days in August to 13 days in November.
• The adult stage over winters in cooler months.

Adult

Management

• Collect and destroy fallen and infested fruits by dumping in a pit and cover with a thick layer of soil or apply lindane 1.3 D over them.
• Plough interspace to expose pupae.
• Encourage parasitoids Opius compensates and Spalangia philippinensis.
• Use methyl eugenol lure trap (25/ha) to monitor and kill adults or prepare methyl eugenol and malathion 50 EC mixture at 1:1 ratio and use 10 ml mixture / trap.
• Use polythene bag fish meal trap with 5 g of wet fish meal + 1 ml dichlorvos soaked in cotton at 50 traps/ha. Renew fish meal and dichlorvos soaked cotton once in 20 and 7 days respectively.
• Use bait spray combining molasses or jaggery 10g/ 1 and one of the insecticides, fenthion 100 EC 1 ml/, malathion 50 EC 2 ml/1, dimethoate 30 EC 1 ml/1, carbaryl 50 WP 4 g /1, two rounds at fortnight interval before ripening of the fruits.
• Spray hostothion 2ml /litre or malathion at 1 ml/1 four times at 15 days interval.
• Rake the soil around the tree during the pest incidence and apply lindane dust 1.3 % at 25 kg /ha.