Trial tackles apple pest by numbers

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

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

The project has potential to change the way codling moth is managed in Australian apples, particularly when used in tandem with other integrated pest management 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. As part of the program sterilised moths will be from Canada for release in the test orchards. The research team will then rigorously monitor the moths’ progress using specific pheromone traps.

This 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 Sally Bound is leading 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 offspring produced, so it interrupts the lifecycle.”

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

The research team will study sterile moth viability and competitiveness, determine the logistics of importation and release and assess the economic impact of the release program, with the aim of developing recommendations for adoption of sterile releases in integrated pest management programs.

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, affecting integrated pest management systems.

Scott Price, orchard manager from R&R Smith, said codling moth was a big issue for the Tasmanian 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 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,” Mr Price said.

Dr Bound said the team would 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.”

The project will run for three years.