No More Coddling for Codling Moth: Sterile insect trial underway in Tasmania

For the first time in Australia, a form of fertility control is being trialled to manage a major pest to the apple industry, codling moth.

Researchers at the Tasmanian Institute of Agriculture (TIA) are partnering with local apple growers to pilot a controlled sterile insect release program.

It has enormous potential to change the way codling moth is managed in Australian apples, particularly when used in tandem with other integrated pest management (IPM) methods.

Codling moth is one of the most economically damaging pests of apples. In an unmanaged orchard they can wipe out 50-90 per cent of the fruit.

The program is importing sterilised moths from Canada for release in the test orchards. The research team rigorously monitor the moths’ progress using specific pheromone traps.

The method is currently used to manage Queensland fruit fly on the mainland and is an environmentally friendly way of controlling insect pests, reducing pesticide use and fruit damage.

TIA Senior Research Fellow, Dr Sally Bound leads the pilot program which is taking place across three apple orchards in Tasmania’s Huon Valley.

″The program works by flooding the wild population with large numbers of sterile males to substantially reduce the number of fertile eggs produced,″ Dr Bound said.

″The moths can mate with each other, but they don’t produce viable eggs and there is no off-spring produced, so it interrupts the lifecycle.

″When this is repeated over a number of seasons, the population crashes and infestations drop below the threshold levels set for pesticide application, meaning growers no longer need to apply pesticides for codling moth, even for export markets that require pest free shipments.″

The research team will assess sterile moth viability and competitiveness, determine the logistics of importation and release, and undertake an economic assessment of the release program, with the aim of developing recommendations for adoption and integration of sterile releases into an IPM program.

Current management strategies for codling moth include monitoring, mating disruption, biological control and chemical pesticide control.

While these strategies can be effective, application of pesticides can disrupt beneficial insects, substantially affecting integrated pest management systems.

Mr Scott Price, Orchard Manager from R&R Smith said codling moth was a big issue for the apple industry.

″Our area around Grove in the Huon is a real hotspot for both codling moth and light brown apple moth,″ Mr Price said.

″I’m really excited about the sterile codling moth technology; I’ve seen the phenomenal results they have achieved in New Zealand.

″For our orchard, we don’t have the luxury of many control options, and the ones we have still result in some damage as they rely on the larvae ingesting the product which can damage the fruit. They are also very weather sensitive and can degrade rapidly with UV and rain.

″If this pilot program stacks up economically and logistically then I think it will be very good for the apple industry in Tasmania and Australia.″

Dr Bound said the team will be repeating the program next season.

″By the end of the second release season we hope to see a reduction in the numbers of wild moths. It can take a few seasons to see a significant drop off in the wild population.″

Fast facts

Sterile insect technology

• Sterile insect technology has been successfully used in Canada with an area-wide approach reducing wild codling moth populations by 94 per cent. They also reduced their chemical use for codling moth by over 96 percent - a win-win situation for both growers and the environment.

• Sterile Insect Release Programs have been undertaken in New Zealand (since 2014), US, Argentina, Chile, Brazil, South Africa, Morocco, Tunisia, and Pakistan.

Production of sterile moths:

• The moths are sterilised in a specialist facility in Canada with highly controlled low dose gamma radiation – like X-rays, but with a shorter wavelength. Gamma rays are also used to sterilise medical equipment in hospitals.

• The same technology is used to produce sterile fruit fly which are currently produced and released in Australia to eradicate fruit fly outbreaks in pest free areas.

• Sterile codling moth are imported rather than produce and irradiate here as there is no culturing/rearing production unit for codling moth in Australia. New Zealand also currently import their sterile codling moths for SIT from Canada.

• The sterile codling moths can be distinguished from wild moths due to a permanent internal pink-red dye marker from the larval diet.

The project runs for three years and has been funded by Hort Innovation, using the Apple & Pear research and development levy and contributions from the Australian Government.

The project is a partnership between TIA, the Tasmanian Government, Fruit Growers Tasmanian, The Department of Agriculture, Fisheries and Forestry, the South Australian Research and Development Institute and Lenswood Coop in South Australia.

TIA is a joint venture of the University of Tasmania and the Tasmanian Government.