Appearance and life-cycle
Only two species of economically important fruit flies occur in Australia. One of these is Mediterranean fruit fly (Ceratitis capitata) which permanently inhabits the growing areas of Western Australia and parts of South Australia. The other is Queensland fruit fly (Bactrocera tryoni) (or QFF), which permanently inhabits parts of the Northern Territory, Queensland, New South Wales and some parts of Victoria. QFF is the primary fruit fly of concern in Victoria.
QFF is a significant horticultural pests. QFF attacks a wide range of host plants, lowering production and making fruit inedible. This can have severe consequences for local and international trade.
QFF host fruit and fruiting vegetables can only be transported to sensitive markets, including the Greater Sunraysia Pest Free Area (PFA) under an industry certification arrangement or a permit issued by a State authority.
Adult QFF are about seven millimetres long and are reddish-brown in colour, with distinct yellow markings.
While QFF activity generally increases in spring as the weather gets warmer, it is not strictly tied to a particular season.If sufficiently warm weather persists into autumn or winter, fruit flies can continue through their life cycle providing that a suitable host fruit or fruiting vegetable is available.
As with most insects, there are four stages in the life cycle:
- Egg - Eggs are white in colour and banana-shaped. They are unlikely to be seen by householders.
- Larva (maggot) - Soon after the eggs have been laid, a small maggot emerges from each. Maggots have cutting jaws which help to tear the fruit into pieces small enough to swallow. Maggots tend to eat towards the centre of the fruit. This also promotes rotting of the fruit, although it may appear to be in good condition from the outside. When the maggot has completed growing, it chews its way out of the fruit, which by then has usually fallen to the ground, and burrows into the soil.
- Pupa - In the soil, larvae become inactive and change into oval, brown, hard pupae, in which adult flies develop.
- Adult (fly) - After hatching, adult flies find a food source. After feeding, the flies mate and each female then searches for ripening fruit which she punctures and lays her eggs in. The punctures ('stings') are very small and can usually only be recognised by an experienced person.
1. Abdomen and eggs of QFF
2. Peach infested with QFF larvae
3. QFF pupae
4. QFF female preparing to lay eggs
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