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Fruit Fly success in the Torres Strait


The Torres Strait is a key line of defence in protecting the horticulture industry from potentially devastating pests present in countries to Australia’s north – the long-running National Torres Strait Exotic Fruit Flies Eradication Program is one of Australia’s biosecurity success stories. APAL recently agreed to continue their contribution to funding this important eradication program. 

What is it?

Exotic fruit fly incursions in the Torres Strait have been managed with annual eradication and prevention activity since 1996. A new five-year exotic fruit fly response plan for 2021-2026 was endorsed on 28 June 2021. 

The response plan targets three exotic species: 

  • Bactrocera dorsalis (Oriental fruit fly – formerly Asian papaya fruit fly) 
  • Bactrocera trivialis (New Guinea fruit fly) 
  • Zeugodacus cucurbitae (melon fly) 

These fruit flies blow in from Australia’s northern neighbours annually during the summer months, making the Torres Strait islands the first and best line of defence.  

Rebecca Sapuppo, Plant Biosecurity and Product Integrity Program

Rebecca Sapuppo is the Manager for Policy, Incident Response & Preparedness in the Plant Biosecurity and Product Integrity Program at Biosecurity Queensland. According to Rebecca, a key strength of this eradication program is the long-term collaboration between government, industry and community groups. 

“There has been an important continuity of knowledge,” Rebecca said. “I’ve been involved with the program since 2002, and a number of officers who had foundational roles in the program are still involved. Maintaining long-term relationships with Indigenous communities and Traditional Owners in the Torres Strait has been key. Being led by the Queensland Department of Agriculture and Fisheries (DAF) in partnership with the Australian Department of Agriculture, Water and the Environment (DAWE), this program can bring together different communities and industry, and give us access to the best science and research across departments to inform our strategies.”  

How does it work?

The remote and scattered islands of the Torres Strait present a logistical challenge. According to Rebecca, much of the technical methodology for annual eradication has stayed the same for the past 25 years.  A combination of trapping, bait spraying and the installation of male annihilation blocks is used to ensure effective surveillance and eradication.  

“Installing male annihilation blocks and bait spraying is labour-intensive, but the techniques have high biosecurity benefits,” Rebecca said. “The wooden blocks with insecticides and lure are put in place in November, nailed onto trees in the northern islands or those where exotic flies are detected. We also use Natralure bait spraying on trees to target the females. The eradication activities continue each year until trapping evidence confirms that exotic fruit flies have been eradicated.” 

DAF officers place male annihilation blocks

While much of the program relies on tried-and-true methods, the response plan itself is constantly evolving. 

“We use the results from trapping to inform our response, and each year’s strategy is unique,” Rebecca said. “Our response plan is designed to be reactive, so we can move very quickly. During the wet season when the exotic fruit flies are likely to be blown into Torres Strait, DAWE do fortnightly clearances of the traps, review the catches and we adjust our response to this real-time data.” 

COVID-19 required its own rapid response, when the officers based on the mainland were unable to travel to the Torres Strait due to restrictions. 

“We had started preliminary training for Indigenous rangers in the Torres Strait Regional Authority (TSRA) in late 2019, but COVID-19 meant we had to fast-track it,” Rebecca said. “They managed a lot of the operational delivery, particularly the blocking field activities.” 

The service arrangement with the TSRA also provides a long-term solution for an even more efficient program. 

“Working with the rangers there means the program isn’t as often interrupted by bad weather or restrictions, and we can send up fewer officers,” Rebecca said. “Our new five-year plan  will continue the partnership with the rangers, and also has a stronger emphasis on communication and engaging with local people to build knowledge and support on the islands.”  

Why is it important?

The risk of exotic fruit fly becoming established on the mainland has impacts beyond Far North Queensland. The presence of pests such as Queensland fruit fly as far south as Victoria has shown how easily these threats can spread and cause destruction throughout Australia.  

“Island eradication scenarios give us a competitive advantage against fruit flies and other biosecurity threats as we are working in a defined area. Without this eradication program best estimates suggest that we could see a mainland incursion within 18 months,” Rebecca said. “The threat to Australia’s horticulture industry is very real. Once an exotic fruit fly gets to mainland, it can spread more quickly and it becomes harder and more expensive to eradicate. 

“The 1995 incursion of Oriental fruit fly in Cairns took 4 years and $34 million to eradicate. As a reasonable estimate, dealing with a similar incursion now could cost around $100 million to eradicate, not including additional cost to industry. By comparison, our program spends around half a million per year on eradication.” 

Maintaining tight control over incursions with ongoing response plans, being proactive, identifying threats and having a coordinated response supported by government is key to the protection of Australian agriculture. 

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