New insect to patrol South Island orchards

South Island pipfruit growers are enhancing their management options for one of the key pests for the pipfruit industry – the codling moth – with the release of a new biocontrol agent.

Pipfruit New Zealand and Plant & Food Research scientists have been preparing for the release of the parasitoid wasp Mastrus ridens, an effective natural enemy of codling moth, which is one of the major pests affecting the New Zealand pipfruit industry. A few were released last year in Hawke’s Bay and Gisborne, but, with support from the Sustainable Farming Fund, the parasitoid will now be released throughout New Zealand over the next few years. More than 60,000 of the parasitoids will be set free this summer into Hawke’s Bay, Nelson/Motueka and Central Otago apple growing regions.

“Codling moth is a major issue for the pipfruit industry, with control of the pest costing between $8 and $12 million each year,” says Dr Mike Butcher, Technical Manager of Pipfruit New Zealand. “Whilst the presence of a single moth in a shipment can impact on market access for all New Zealand apple exports to codling moth sensitive markets, the industry is also focused on reducing the use of chemical pesticides. This means we must find new ways to control pests, and the introduction of the Mastrus wasp as a biological control agent is an important new component to our system that currently includes mating disruption, a codling moth specific virus and selective chemistry. This release is an important step in meeting quarantine requirements for our premium markets.”

The Mastrus female attacks the cocoons of codling moths, laying its eggs on the moth larvae. When the wasp larvae hatch, they feed on, and eventually kill, the codling moth larva. They then emerge as adult wasps to disperse and seek new codling moth larvae on which to lay their eggs.

“Biological control agents, such as parasitoid wasps, play an increasingly important role in controlling pests as chemical interventions are reduced,” says scientist John Charles from Plant & Food Research. “This species, which originated in Kazakhstan, has been established in other countries, particularly in the USA, for control of codling moth, and these initial releases in New Zealand will help us to determine how well they survive in our environment and control the pest.”

The Mastrus wasp was approved for release by the Environmental Protection Agency in June 2012, and thousands have since been reared in captivity in preparation for the release programme.

Video of the Mastrus wasp can be seen on the Plant & Food Research YouTube channel.