It’s a common pest that attack most of soft skinned fruits and vegetables posing a great threat on export markets especially for fruits. Basically the pest (females) punctures into the fruit and lays eggs under the fruit skin, the eggs hatch into larvae that start feeding on the fruit tissues before dropping to the ground where they pupate.
There are many species of fruit flies some being monophagous (host specific) while others are polyphagous (non host specific).
Some are host specific (attack a specific crop) while others are non host specific ( being polyphagous thus attacking a wide range of crops).
|Fruit fly species||Host crop/s|
|Mango fruit fly||Mango, guava, orange, custard apple, Marula, Apricot.|
|Natal fruit fly||Arabica coffee, custard apple, papaya, Mango.|
|Jointed pumpin fly||Pumpkin and other cucurbits|
|Mediterranean fly||Wide range of crops|
|Melon fly||Cucumber, Watermelons, edible gourd, butternuts, pumpkin|
|African invader fly||Primary host-Mango
Secondary hosts: Tomato, banana, Marula, guava, Avocado
The pest damages the fruits by puncturing through the skin and laying eggs inside, the emerging larvae feed on fruit tissues. Affected fruits develop soft tissues attracting mould and this lead to fruit rotting or premature fruit fall.
Signs and symptoms of attack
Basically the visible signs are the punctures on fruit skin made by females when laying their eggs, tissues around the punctures become necrotic. Small holes develop in later stages following the leaving of larvae stages once they hatch from the eggs. Affects fruits become soft and develop maturity colors prematurely and may eventually drop off the plant.
Fruit fly control measures
For effective pest control one must employ IPM strategies which are cheap, environmentally friendly and allow achievement of MRLs (maximum residue levels) at ease.
Cultural control measures
Practice good field sanitation: Remove all fruits with dimples and oozing clear sap which is the actual manifestation of fruit fly attack. This method is more effective that when on corrects fallen fruits on the ground as the larvae leave the fruits and burrow in the soil to pupate. This can be done twice a week to ensure effective control of the pest. Infested fruits should be fed to livestock or buried deep in the soil or put in black plastic papers and exposed in the sun to kill the larvae stages.
Early harvesting: Involves harvesting fruits immediately they are physiologically mature. It’s only applicable in fruits such as papaya and bananas since fruit flies do not attack these fruits when they are green. In the control of some fruit fly species such as Bactrocera this control strategy may not apply as the species attack fruits when green and ripe.
Preserve natural enemies: Avoid using broad spectrum pesticides on your farm which kill even the beneficial insects/parasitoids/natural enemies eg braconid wasp that control the pest.
Physical control means: Can be achieved by fruit bagging or using pheromone traps/traps designed to lure and kill the pest (lure and kill technique).
Fruit bagging technique in Rajshashi India
Chemical method: Should be used sparingly to avoid incurring high cost of fruit production, ease achievement of maximum levels (safe fruit production for human consumption) and environmental conservation. A spray program is essential to effectively control the pest and produce high quality fruits free from pest damage. Chemicals such as karate, match, arginate, alpha 10 EC can be used to contain the pest.