Wednesday, May 14, 2014

UST GS Fruit Fly (Dacus spp): Scourge of Fruit Crops

Dr Abe V Rotor
Living with Nature - School on Blog
Paaralang Bayan sa Himpapawid (People's School-on-Air) with Ms Melly C Tenorio
738 DZRB AM, 8-9 evening class Monday to Friday
Fruit fly maggots cause damage to bananas.


Fruit fly prepares to lay eggs on Mabolo


Fruit flies are found all over the world in different species and in a wide variety of hosts. In the Philippines there are two main species of fruit flies: Dacus cucurbitae, which attacks plants of the squash family; and Dacus dorsalis, which attacks mango, macopa, guava, banana, mabolo, cashew, and other orchard crops.

Fruit flies easily get through port quarantine. Our fruit flies can ride on infested fruits and attack oranges, apples, pears, apricots and the like in other countries. Philippine fruits for export, specially mango, are closely inspected at source because of this problem.

Dacus flies are relatives of houseflies and mosquitoes; they all belong to Order Diptera. They undergo complete metamorphosis: egg, maggots, pupa and adult. It is the maggot stage that is most destructive. The adult lays eggs on the fruit with an ovipositor. On hatching the maggots tunnel and feed inside the fruit. When ready to pupate they bore their way out and momentarily wait until they become adult flies. Adult flies destroy by ovipositing on fruits at different stages.
Dacus cucurbitae attack young fruits of ampalaya, cucumber and the like; while Dacus dorsalis prefer ripening fruits like mango and guava.

There is a folk belief that sudden rainfall in summer spawn maggots. I have observed this in guava and macopa in particular. Rain triggers fruit flies to become active with the ripening of fruits. Untimely rain causes fruits to fall to the ground. It is in these spoiled fruits that enable the pest to complete, if not repeat, its life cycle.

A practical way to save fruits from this pest is to cover the fruits with paper before they are attacked. Cover ampalaya and cucumber with rolled used bond paper or newspaper soon after the fruit is formed, then monitor the growth of the fruit inside the rolled cover until they are ready for harvesting. You can try this technique on mango. Use plastic bag for nangka and banana.

If the pest can't be controlled this way, then resort to chemical spraying. Consult your nearest agriculturist.~

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