Operations
Lifecycle &
identification
Mediterranean fruit fly, Cape fruit fly and Oriental fruit fly share similar biology and life cycles.
Life Cycle
Under favourable conditions female fruit flies become sexually mature and capable of laying eggs about 5 days after they emerge. After mating they actively seek out ripening fruit and deposit their banana-shaped eggs in a small cavity just below the skin. Oviposition sites appear as small brown spots on the surface of the fruit, under that is a cavity with one to more than 20 eggs.
After 2 to 3 days in favourable conditions, the transparent larvae hatch and start feeding on the flesh of the fruit, slowly tunnelling towards the core. The larvae have a sharply pointed front end with no obvious head, and a blunt rear end, and become cream-coloured as they get older. Early infestation is often indicated by a brown colouration of the fruit flesh in the area of feeding due to oxidation of the tissues. From about 7 to 40 days later, depending on fruit kind and temperature, the larvae reach maturity (8 to 10 mm long), when they leave the fruit, fall to the ground, and pupate just below the surface of the soil. About 8 to 40 days later, depending on temperature, the adult flies emerge from the pupae, crawl up to the soil surface, and the cycle is complete.
During warm conditions and in ripe fruit, the life cycle can be completed in as little as 3 to 4 weeks. This duration can increase to about 2 or 3 months in winter or where eggs are laid in greener fruit.
Identification
Mediterranean fruit fly (Mediterreënse vrugtevlieg (Medvlieg) – Ceratitis capitata)
Eggs are white and banana-shaped, about 1 mm long. Mature larvae are creamy-white, legless, 7 to 9 mm long, and the body tapers from a blunt rear end. Pupae are reddish-brown, cylindrical with rounded ends, and 4 to 6 mm. Pupation usually occurs in the soil. Adults are slightly smaller than a housefly, about 3 to 5 mm in length, yellowish orange-brown in colour, with some orange-brown markings on the wings. The eyes are reddish purple with a green fluorescence.
Cape fruit fly (Kaapse vrugtevlieg – Ceratitis quilicii)
Immature stages are very similar to Medfly, but slightly larger. The adult is about the size of a housefly, up to 8 mm in length, and browner than Medfly. The eyes are reddish purple, usually with a blue fluorescence. The male has black ‘feathering’ on the lower end of the middle legs. As in Medfly, wings are also patterned but wing bands are brown and generally darker than on Medfly. Ceratitis quilicii can complete its immature development in 23 – 65 days at 30°C – 15°C (Tanga et al., 2015). Adult females lay eggs under the fruit skin. Eggs are usually white to creamy yellow in colour. The area on the fruit skin where eggs are laid usually becomes discoloured.
Ceratitis quilicii is found throughout eastern and southern Africa, from the Western Cape northwards till Kenya. It appears to prefer cooler conditions than its close ally, C. rosa. The species was also introduced into Mauritius and La Réunion. Not established outside Africa.
Photo credit Shelley Johnson
Oriental fruit fly (Oosterse vrugtevlieg – Bactrocera dorsalis (Bd)
Bactrocera dorsalis has invaded Africa from Sri Lanka and is considered as an extremely serious fruit pest.
It is on the quarantine pest list of plant protection agencies from various countries (i.e. EPPO, APPPC, COSAV, CPPC, IAPSC and OIRSA). It has spread to more than 10 countries in Africa, including Mozambique and Namibia.
This fruit fly is highly invasive with high reproductive potential, and has a long list of host plants, including citrus, mango, cashew, papaya, guava, pepper and several wild host plants. The main pathway for fruit flies to spread from one country to another is through the international movement of infested fruits.
This fly differs noticeably from the other two species mentioned above. Eyes are blue-black, and wings are clear with prominent, dark leading edges.
