A new National Fruit Fly Strategy 2020-2025, expected to be launched in September, will provide a strong framework for stakeholders to coordinate fruit fly activities across Australia.

Managed by the National Fruit Fly Council, the strategy includes an implementation plan with planned activities for stakeholders and the Council.

“Fruit flies are Australia’s most significant horticultural pest and a growing problem. There is a wide host plant range, including grapevines, and the pest has huge impacts on domestic and international market access, and production costs,” said Christina Cook, Manager of the National Fruit Fly Council.

“The aim of this new strategy is to minimise the damage of fruit flies in infested areas, prevent exotic fruit flies from entering Australia, and to prevent the spread of fruit flies into pest free areas, including Tasmania and the Riverland in South Australia.”

While Australia has more than 300 species of fruit fly, only two are economically important:

  • Queensland fruit fly (Qfly), which is present in Australia’s northern and eastern states.
  • Mediterranean fruit fly (Medfly), which is present in Western Australia.

According to the new strategy, key challenges facing fruit producers include international confidence in our ability to control the pest, increasing scrutiny of our systems and produce, chemical limitations for control, peri-urban pest threats and exotic fruit fly threats.

“Any time we have fruit fly detections in pest free areas, they are reported around the world. Qfly is a major concern for our international markets as none have this pest. It’s a uniquely Australian problem, that none of them want,” Christina said.

“So, it’s vital that we control the pest and prevent its spread, to retain confidence in our biosecurity system.”

Christina said outbreaks of Qfly and Medfly in new areas also lead to increased scrutiny of our pest control systems and our produce quality.

“Added to this, there are chemical limitations, which is a significant issue for industries such as table grapes. There are few products that can be used for fruit fly control and maximum residue limits (MRLs) are an ongoing challenge,” Christina said.

Christina said poor fruit fly management in suburban backyards can also add significant pressure to the fruit fly system.

“Fruit flies can harbour in peri-urban areas and then move into production areas, so it’s critical that we address the backyard threat,” Christina said.

To illustrate the importance of backyard pest control, the South Australian government has spent considerable time and money controlling Medfly outbreaks in suburban Adelaide to ensure continued freedom of fruit fly in production areas.

“Medfly is a big concern, as we don’t have this pest in the main horticultural regions of Australia,” Christina said. “In Western Australia, where it’s established, the most commonly infested fruits include apricots, nectarines, peaches, mangoes, persimmons, apples, pears, grapes and mandarins.

“If it moves into eastern production areas, we know that the pest is more tolerant of cooler conditions than Qfly, so this could be a concern for many crops, including winegrapes.”

Exotic fruit fly risks are also a strong focus of the fruit fly strategy, building on the work of the annual eradication program in the Torres Strait which has been running successfully since the mid-1990s. “This is paramount to protecting mainland Australia from exotic fruit fly incursions,” Christina said.

“The wine industry also has an important role to play. The wine industry has a shared responsibility for controlling fruit fly in risk areas and grapegrowers should be aware of the threats, including the Medfly and exotic fruit fly threats, which could be a direct threat to winegrapes.”

Winegrapes as a host for Qfly

The significant Qfly damage recorded in the Hunter Valley during 2007-2008, coupled with successful Qfly development in several winegrape varieties, has confirmed winegrapes can be a suitable host for Qfly development.

The Department of Primary Industries New South Wales’ Primefact has suggested that it was likely the mild and wet winter conditions coupled with the humid summer conditions that contributed to the enhanced development and high survival rates of Qfly in this case.

In addition, despite the availability of other host fruits at the time of ripening of winegrapes, it appeared likely that the Qfly population was so large in this season that even traditionally non-preferred hosts such as winegrapes were attacked.

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