Natal Fruit Fly
Natal Fruit Fly, Natalse Vrugtevlieg (Afr.)
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The Natal Fruit Fry is one of the most common known pests in the agricultural industry. Significant damage is only caused by larvae. Three to six generations can occur per year. The life cycle is weather and resource-dependent. During warm conditions and in ripe fruit, the life cycle can be as short as three to four weeks. During the winter it can be two to three months.
Females deposited eggs under the skin of fruit. Emerged larvae starts feeding in the fruit leading to fruit loss.
Adults are up to 8mm in length. They are brown with reddish-purple eyes. The wings are patterned with brown bands. Pupae are cylindrical with rounded ends, and 4-6mm in length. Initially, they start being straw-coloured and then become dark reddish-brown. Pupation usually occurs in soils. Larvae consist of three instars. The first instar is translucent, where subsequent instars are white to cream-coloured. Mature larvae reach a length of 9-11mm. Larvae are legless, and the body tapers from the posterior to the anterior end. Black mouth hooks are visible in the second and third instars. Eggs are white, smooth and banana-shaped with a length of 1 mm. Eggs are laid under the skin of the fruit.
Only the larvae cause damage to host plants. Eggs are deposited just under the skin of the ripest or ripening fruit. Sites, where eggs are laid, resemble discoloured pin-prick sites. The larvae feed on the fruit, tunnelling to the centre of the fruit. Feeding activity of fruit flies is often coupled with infections by micro-organisms and secondary pests, resulting in the fruit to a pulpy mass.
This species was initially described from Mozambique. It is endemic to Africa and the Indian Ocean Islands.
Biological agents include entomopathogenic bacteria (e.g. Bacillus thuringiensis and Saccharopolyspora siniosa), fungi (e.g. Beauveria bassiana, Entomophthora spp. and Metarhizium anisopliae), nematodes (e.g. Diplogaster sp. and Steinernema spp.), ants and spiders. Sanitation - pick up fallen fruit and bury the fruit so that fruit flies won't be attracted.
Fruit fly bait - a protein attractant mixed with a synthetic or natural insecticide. Sterile insect technique (SIT) - a technique which is used to mass-rear insects and mass-sterilization of males. Males are then released and will mate with females. No offspring is produced and thus breaks the reproductive cycle, known as autocidal control.