South Australia is proudly fruit fry free, but recent metropolitan Adelaide outbreaks have put the biosecurity industry and producers on high alert.

Biosecurity SA is currently managing three fruit fly outbreaks in metro SA: two Queensland fruit fly outbreaks and one Mediterranean fruit fly outbreak. A fourth outbreak of Queensland fruit fly at West Hindmarsh was successfully eradicated in April.

“South Australia has a 100% record in successfully eradicating these isolated incursions which have not impacted on our fruit fly free status for the rest of our State,” said Nick Secomb manager of Plant Health Operations at PIRSA Biosecurity SA.

“PIRSA maintains a rigorous fruit fly program to ensure the pest does not become established here. By ensuring South Australia retains its fruit fly free status, not only do we protect the production of our fruit and vegetables, but it also helps the state’s access to lucrative international horticulture export markets – which in 2016-17 was worth $1.25 billion.”

When a fruit fly outbreak occurs:

  • A quarantine area (‘Outbreak Zone’) of 1.5km radius is established, from which host fruit (including grapes) cannot be removed.
  • A suspension zone of up to 15km is established, within which host fruit (including grapes) must be treated prior to removal using secure transport arrangements.
  • Fallen fruit in the quarantine area is collected and destroyed.
  • Bait spotting is undertaken.
  • Sterile fruit flies are released to confirm that eradication has been successful

“In a metro setting, an outbreak means people can’t move and share fruit as they might otherwise do. But in a commercial setting, it’s much more difficult. These are growers who are trying to sell commercial product – it’s their livelihood,” Nick said.

Being fruit fly free has significant benefits for South Australian grape and horticultural producers including access to markets without the need for additional treatments. It is also important for residents who can grow fruit and vegetables at home without the need of pesticides.

To further assist in planning and preparing for potential outbreaks so that responses can be rapid and effective, Biosecurity SA is running a fruit fly outbreak simulation in the Riverland in early May, to test the region’s preparedness. Vinehealth Australia will report on the results of the simulation in a future edition.

Sterile flies bred in SA

Is it a bird? Is it a plane? No, it’s two million sterile Queensland Fruit Flies descending over Adelaide. Using a plane to drop sterile flies into outbreak zones may seem strange, but it’s a proven eradication technique.

Sterile insect technology (SIT) is a method where sterile male flies are released to mate with any remaining wild female fruit flies, ultimately removing the wild fly population. The sterile flies are also bred with superior physical characteristics to make them more attractive to females.

The decision to conduct an aerial release of the sterile Queensland fruit fly (Qflies) as part of Biosecurity SA’s eradication response to the current metropolitan Qfly outbreaks is made in consultation with entomologists and based on factors including the time of year the detections are made and the number of flies discovered. The release in April included the first flies produced at the $3m state of the art National SIT Facility in Port Augusta.

The Queensland fruit fly alone is estimated to cost the Australian horticultural industry $300 million in lost fruit and vegetables each year.

The sterile fly release and the National SIT Facility is part of the $45m national SITplus program research and development partnership. Funding partners include Hort Innovation, Macquarie University, the South Australian, Victorian and NSW Governments, CSIRO, the New Zealand Institute for Plant and Food Research, and a range of levy paying industries.