New Zealand apple and pear growers introduced a new method of fighting orchard pest the codling moth with the release of a small parasitoid wasp on Thursday.

Photo: Plant & Food Research, New Zealand

Plant & Food Research scientists and Pipfruit New Zealand released 1,000 Mastrus ridens as a form of biocontrol. The female wasps attack codling moth coccoons and lay eggs on the moth larvae.

Codling moths are a pest that affect apple and pear orchards worldwide. The insect is a caterpillar that bores into apples and pears and feeds on their seeds, causing potential damage to the fruit.

Mike Butcher, technical manager of Pipfruit New Zealand, said the moths cost between NZ$8-$12 million (US$6.6-9.93 million) each year to control. The introduction of the parasitoid wasp will contribute to the overall approach to pest management.

"It’s a benefit that accrues to a system’s approach where we’ve got all of those other processes in place and the parasitoid will be lowering the background population of the codling moth in the general environment," Butcher said.

"What it will do is give us another component in our system’s approach to management so that we have a much higher assurance of market access requirements for more sensitive markets."

The use of biological control agents should also have the effect of reducing chemical pesticides, a Plant & Food Research release said.

After the campaign in Hawkes Bay, the wasp is expected to be released in other sectors of New Zealand.

The Environmental Protection Agency approved the Mastrus wasp for use in June.

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