Bactrocera cucurbitae / Dacus cucurbitae– Melon fruit-fly (Coquillett)
- Class– Insecta
- Order– Diptera
- Family– Tephritidae
- Genus– Bactrocera
- Species– cucurbitae
The melon fruit fly was first observed in Hawaii Islands in 1898 but since 1903 it has a wide range of distribution in Australia, Myanmar, China, East Africa, Formosa, India, Japan, Malaysia and Pakistan. It is commonly found damaging vegetables throughout India.
It is most destructive fruit-fly of musk-melon and pumpkins, and also found damaging other cucurbitaceous vegetables viz., Cucumber, Ridged gourd, tomatoes and Bitter gourd.
It is reddish brown fruit-fly having black and white spots. The wings are provided with brown bands and spots on the apex. Commonly it is found sitting in wing-spread position slightly more than the house fly. It measures about 7 mm in length and 3 mm in breadth with a wing expanse of about 14 mm. Some other species of Dacus are found damaging ripening fruits of mango, peach and guava.
The adult female fly just after emergence mates with the male at dusk and starts egg laying within 14 days. In winter season this pre-oviposition period may prolong. The fly selects suitable site for egg laying, makes cavity in soft fruits by the sharp ovipositor, lays about 12 cylindrical white eggs mostly in the evening hours. After egg laying the female releases a resinous secretion which cements the tissues near the puncture and makes it water-proof. One female lays, on an average, 58-59 eggs in 14-54 days. After 1-9 days of incubation period eggs are hatched into maggots. These maggots feed continuously on the pulp of the fruit resulting in its complete destruction. They can jump to a height of one foot which helps them in dispersal. The infested fruits decay due to secondary bacterial infection. The larva attains full grown adult stage after 3 days in summer and 21 days in winter and leaves the fruit. After falling down to the ground, they burrow in the soil up to the depth of about 5 cm and pupate there. The pupae are barrel-shaped and light brown in colour. The adult fly emerges out from the pupa in the morning hours after 6-9 days in rainy season and 21-28 days in winter. There are several overlapping generations in a year specially active throughout summer and autumn in Uttar Pradesh.
The damage is caused due to the maggots by feeding on the almost ripe fruits, riddling them and polluting the pulp. The maximum damage is caused in July and August when about 50% fruits are under severe attack by this pest.
Prevention and control
- The infested fruits should be removed and destroyed regularly.
- Under the infested plants, constant stirring of soil should be performed.
- The fruits meant for food may be covered with cloth bags.
- The spraying of malathion 0.05% +molasses 1% or with trichorphon 0.15% is effective to control the pest.
- Dimethoate 0.03% is effective to decrease the pest population.
- The poison baits containing 500gm of protein hydrolyzate and 2.5 kg of 50% malathion in 10 litres of water attracts and kills the adult flies.
- Natural enemies-several braconids like Opius fletcheri. Silv. and Opius Silv, parasitize the pupal stage of the pest and thus have a good checkup on population control.
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