The key to using a catch crop to reduce onfarm nitrate leaching is to get it in the ground as soon as possible after winter feeding, says Plant and Food scientist Dr Brendon Malcolm.
Plant & Food Research scientists, with support from Pipfruit New Zealand, have been investigating the potential for Mastrus ridens, a small parasitoid wasp, to control the codling moth, one of the major pests affecting the New Zealand pipfruit industry.
Following EPA approval, field appraisal will take place over the next few years to measure the effectiveness of the wasp as a long term biological control agent. The first release in commercial orchards, of 1000 individuals, has been made in Hawke's Bay this week.
"Codling moth is a major issue for the pipfruit industry, with control of the pest costing between $8 and $12 million each year," says 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 ultimately 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, and thousands have since been reared in captivity.
A video showing the female Mastrus wasp laying her eggs can be found at http://plantandfood.us5.list-manage.com/track/click?u=1b46d14e528ad30bae8b3663c&id=4098e51aff&e=e26d8a2d96.