In early 2005, a new fruit fly, Bactrocera invadens, was identified in Ghana. This fruit fly attacks several fruits and vegetables such as mango, citrus, guava, papaya, tomato, eggplant and pepper. The adult fly is brown to dark-brown with yellow stripes on the thorax. Both males and females are similar in appearance but damage is often caused by females. They pierce the fruit/vegetable to lay eggs. The eggs hatch into creamy maggots (larvae) that grow up to about 10mm long. The maggots live and feed inside the fruit and destroy the pulp. Fruits/Vegetables that are attacked at an early growth stage may drop, but those attacked at a late growth stage may develop to maturity and be harvested with the larvae.
Figure 1. Pictures of the invasive fly, Bacterocera invadens.
Figure 2. Typical life cycle of a fruit fly. Note how fallen fruits not collected aid in the completion of the cycle
Figure 3. fruit fly damage symptoms on mango.
Left= Point of egg deposition and
Right = Internal damage caused by developing larvae
POTENTIAL ECONOMIC LOSSES
- Reduction in quantity and quality of fruits and vegetables
- Reduce income to farmer
- Reduction in foreign exchange earnings
- Ban on fresh fruits and vegetables imports from Ghana
- Total collapse of horticultural industry
All management practices should be adopted communally (by all farmers).
- Farm sanitation:
- Keeping farm clean(low weeds)
- Picking dropped fruits/vegetables regularly from the farm
- Burying picked fruits/vegetables deep in the soil (at least 60cm below the soil surface)
- Putting fruits/vegetables in thick black plastic bags and exposing to sunshine for up to 7 days.
Figure 4. Various ways of fruit disposal, A= In a thick black polythene bags and exposed to the sun for up to 7 days, and turned over regularly. B= Digging and burying fruits at least 50cm deep.
Fruits may also be placed in an augmentorium (tent-like structure that allows natural enemies to escape while keeping the fruit flies).
- Cultural Practices
- Use of designated paper bags to cover well developed fruits. This is usually used in very high priority crops over small areas or in places where cost of labour is very cheap.
- Harvesting fruits/vegetables early (physiological maturity) to prevent the full attack of the flies.
- Avoiding alternate host plants (guava , sheanut, soursop, etc.) in and around plantation or subjecting them to the same control treatments.
- Trapping/baiting Techniques
- Trapping: Trapping adult flies with recommended pheromone traps
- Baiting: Using food baits and insecticide mixtures such as:
- Hydrolyzed protein + insecticide
- Yeast extract + insecticide
Avoid applying insecticide-laced food baits directly on fruits.
Fruit flies attack fruits/vegetables even after harvest. Move harvested fruits/vegetables out of the field as early as possible and keep in a cool fly proof shed/building.
Other post-harvest options available for fruit fly management include:
- Hot water treatment
- Vapour treatment
- Cold treatment
- Hermetic treatment
Avoid excessive spraying of insecticides because of their adverse effects on the beneficial insects such as pollinators and natural enemies.
Horticulture Development Unit
Export Market &Quality Awareness
For further information
Contact the nearest
MOFA Office or HDU or
Plant Protection and Regulatory Services
Directorate (PPRSD) of MOFA