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Club Medfly

24 November - Western Australia is trialling a genetically modified Mediterranean fruit fly (Medfly) strain produced by UK based company Oxitec.

The males from this strain harbour a self-limiting gene which if passed on to female offspring will cause these to die before they can reproduce.

The Medfly is a pest of cultivated fruits and fruiting vegetables causing millions of dollars in lost production each year.

With the new technology, Western Australia hopes to have a cheaper and more effective pest control at its disposal than the current method, which requires that male flies sterilised through radiation are introduced into wild populations over a series of releases.

The Sterile Insect Technique (SIT) substantially weakens the vitality of male flies, while the purpose-bred male fruit flies are expected to be as vigorous as wild males.

The researchers from the Western Australian Department of Agriculture and Food will test this under glasshouse conditions, and they will also determine whether the 'Oxitec' strain can be reared successfully and cost-effectively in a controlled laboratory environment.

In an expert reaction provided by the Australian Science Media Centre, Professor Tony Clarke, QUT,* pointed out that as the flies are genetically modified it greatly limits their use under current legislation.

"Importantly, the lethal gene must be 'switched off' in the factory, otherwise the flies could not be reared.

"This requires the addition of tetracycline hydrochloride to the fly diet.

"Tetracycline is an antibiotic and how the spent, tetracycline-dosed larval diet from a fruit fly factory (which may run to several tonnes per week) will be properly disposed of will need to be addressed.".

However, according to Oxitec's Dr Neil Morrison, the amount of tetracycline (tet) antidote waste would be insignificant compared to usage for pets, farming and human therapeutic use. And he said that there there were numerous ways medfly feed could be treated to remove tet before disposal as it rapidly degrades in the presence of UV light and heat (click here for full comments).