CUCURBITS :: MAJOR :: PEST OF FRUIT FLIES

1. Fruit flies: Bactrocera cucurbitae (Coquillet) (Tephritidae: Diptera)
Distribution and status
         Commonest and most destructive pest throughout India. Also found in Pakistan, Myanmar, Malaysia, China, Formosa, Japan, East Africa, Australia and the Hawaiian Islands Two other allied species common in India are Dacus ciliatis and Bactrocera dorsalis.
Host range: Melons, tomato, chillies, guava, citrus, pear, fig, cauliflower, etc.
 Damage symptoms
Only the maggots cause damage by feeding on near-ripe fruits, riddling them and polluting the pulp. Damage by the maggots of this pest causes oozing of brown, resinous fluid from fruits and the fruits become distorted and malformed. The maggots feed on the pulp of fruits and cause premature dropping.  The attacked fruits decay because of secondary bacterial infection. After the first shower of the monsoon, the infestation often reaches 100 per cent.
Bionomics
Maggots legless and appear as headless, dirty-white wriggling creatures, thicker at one end and tapering to a point at the other. The adult flies are reddish brown with lemon-yellow markings on the thorax. Adult flies emerge from pupae in the morning hours and mate at dusk. The female, on an average, lays 58-95 eggs in 14-54 days. Egg period 1-9 days, larval period 3 - 21 days. It pupates deep in the soil. The pupae are barrel-shaped, light brown, pupal period  6-30 days. There are several generations in a year.
                                              

Management

• Collect infested fruits and dried leaves and dump in deep pits.
• In endemic areas, change the sowing dates as the fly population is low in hot dry conditions and at its peak during rainy season.
• Frequent rake the soil under the vine or plough the infested field after the crop to kill pupae.
• Use ribbed gourd as trap crop and apply carbaryl 1.0 kg  or malathion 1.0 L/ha in 500 L water  on congregating adult flies on the undersurface of leaves.
• Use attractants like citronella oil, eucalyptus oil, vinegar (acetic acid), dextrose and lactic acid to trap flies.
• Apply the bait spray containing 50 ml of malathion 50 EC + 0.5 kg of gur/sugar in 50 L of water per ha. Repeated at weekly intervals. Keep the bait in earthen lids placed at various corners of the field.
• Spray the bait on the maize plants grown as trap crop
• Use fly trap: Keep 5 g of wet fishmeal in plastic container  with six holes (3 mm dia), two cm from the bottom of the bag. Add a drop (0.1 ml) of dichlorvos in cotton plug and keep it inside the bag. Dichlorvos should be added every week and fishmeal renewed once in 20 days (20 traps/acre).
• Use fly traps having methyl eugenol soaked plywood piecies (2” x 2”). Collect and destroy the flies.
• Conserve pupal parasitoids viz.,Opius fletcheri, O. compensatus and O. insisus (Braconidae), Spalangia philippinensis and Pachycepoideus debrius. (Pteromalidae), Dirhinus giffardi and D. lzonensis . (Chalcididae).

Caution:
In cucurbits, DDT, lindane 1.3 D, copper oxychloride, Bordeaux mixture and sulphur dust should not be used as these are highly phytotoxic.