30% to 40% of crop harvest is lost due to pest and diseases, thus there is need for appropriate measures to reduce the situation. One of the most destructive pests is fruit fly. It is a key horticultural pest which attacks both fruits and vegetable crops like Mangoes, citrus, melons, papaya, guavas, pumpkins, over ripened tomato, grapes among other fruits and vegetables.
Fruit fly is a two winged insect with wings spotted with brown colour.Their body is yellowish and have black spots on thorax.
It is very destructive on ripening mangoes where the adult fly punctures the skin and lays eggs inside the fruit. The eggs hatch to larvae within 2-4 days and then feed on the flesh causing the fruit to rot. Through the openings, bacteria enter in. The activity of the maggots and the bacteria causes the fruit to rot internally and often affected fruit fall prematurely from the tree. A fully mature maggot then leaves the fruit and burrow into the soil and pupate. Then from here the adult fly emerges and starts to invade the mangoes in the following season.
What is the critical stage for fruit fly damage to mangoes?
The fruit fly damage invades mangoes during the fruiting season. The most destructive stage is towards fruit ripening.
How can I identify the fruit fly invasion?
When small /young fruits develop soft patches/spots and fall down prematurely.
Small holes on the fruit, Punctured fruits
Presence of small black spots /dots on the fruits
Part of the fruit may become yellow colored prematurely
Presence of maggots, rotting and oozing sap on sliced mango.
Extreme falling /dropping of mango fruits.
Nb: The pest eradication requires a combined approach i.e. integrated pest management practices in order to control them. These practices include;
Field sanitation
- Collect fallen fruits and destroy to break pest lifecycle. Can put them in tied plastic bags and exposing them to sun heat for several days to rot and kill the maggots.
- Collect and destroy all fallen fruits at least twice a week during the fruit season.
- Do not put collected damaged fruits into compost heaps. Instead, burn them or bury them at least 50 cm deep, so that the fruit flies cannot reach the soil surface.
- Remove fruits with dimples and those that ooze clear sap.
- Whenever possible, you can also wrap the fruits in newspaper or paper bags to prevent fruit flies from laying eggs on the fruit. This has to be done well before the fruit matures.
- Pick overripe fruits, as they attract fruit flies
- Till the orchard top soil 5cm – 10cm deep )to expose pupae to sun , birds etc
- Weed around the fruit orchard to make it clean
- Flood beneath the Mango trees to suffocate and kill the pupae
Population monitoring
Can be done through use of traps and baits
- Use trap and baits ( ½ cup (150ml) vinegar mixed with water or
- Use pheromone traps at 1 trap for 5 -10 trees
Biological control practices
Natural enemies for fruit fly includes ladybirds, wasps, spiders and parasitic fungi, birds, poultry.
Prevention
- Avoid planting mango trees near host plants like, guavas, citrus, melons, papaya etc
- Keep the orchard canopy open to improve aeration
- Harvest early when crop is mature, over ripe fruits attract fruit flies
- Plant lantana camara hedge rows to attract and host natural enemies like ants, birds etc
- Release poultry in the orchard to feed on pupae at the base of plants