Wasps unleashed to solve moth problem

A wasp originating from Kazakhstan is to be unleashed in Nelson region orchards to deal to the codling moth pest.

Pipfruit New Zealand and Plant & Food Research scientists have been preparing for the release of the parasitoid wasp Mastrus ridens, a natural enemy of codling moth, which is one of the major pests affecting the pipfruit industry.

A few were released last year in Hawke's Bay and Gisborne, and now with support from the Sustainable Farming Fund, the parasitoid will be released throughout New Zealand over the next few years.

More than 60,000 of the parasitoids will be set free 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 million and $12m each year," said 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.

John Charles, from Plant & Food Research, said the species had been established in other countries for control of codling moth.