Cucurbit Fruit Fly Control

Symptoms

The female fly punctures young fruits to lay eggs, leaving small oozing marks. Maggots tunnel inside the fruit, which then becomes deformed, develops brown rotten patches and starts to decay with a bad smell. Infested fruits drop prematurely, and on cutting them whitish maggots are found feeding in the pulp.

Damage

The melon fruit fly is the most destructive pest of cucurbits and can cause fruit losses of 30 to 100 percent, being worst in bitter gourd, snake gourd and other soft fruited gourds. Damaged fruits are unfit for market and rot quickly. Losses are highest during the rainy season when humidity favours the fly.

Organic & cultural control

Collect and destroy all fallen and infested fruits daily by burying deep or burning to kill the maggots inside. Install cue lure pheromone traps at about 8 to 10 per acre to trap male flies, and use bait splash of jaggery or protein with a small amount of insecticide on a few plants. Bag young fruits in paper or cloth, plough the field to expose pupae, and grow in the early season to escape peak fly.

Chemical control

Direct cover sprays are of limited value because maggots are protected inside the fruit, so the main chemical tactic is bait application. Prepare a bait of jaggery or molasses with a recommended insecticide such as malathion and spot spray it on the underside of leaves, repeating weekly. Avoid blanket spraying of the whole crop. Use only labelled products at the correct dose, follow the pre-harvest interval and consult your KVK or agronomist before spraying.

Always follow the product label, the recommended pre-harvest interval, and your local KVK or agronomist. Pesticide approvals change, so verify before use.

Prevention

Practise strict field sanitation by collecting and destroying fallen fruits, which is the single most important step. Use cue lure traps for monitoring and male annihilation, plough fields after the crop to kill pupae, and follow crop rotation. Time sowing so fruiting avoids the peak rainy season, and consider community wide area management for best results.