Mass rearing and release of Mastrus ridens (Hym: Ichneumonidae) a parasitoid for the biological control of codling moth Cydia pomonella.

Abstract

ABSTRACT Mastrus ridens (Horstmann) (Hymenoptera: Ichneumonidae) was imported into New Zealand quarantine from Argentina in 2009 as a potential biocontrol agent for codling moth (CM), Cydia pomonella (L.) (Lepidoptera: Tortricidae). A laboratory population of M. ridens had been maintained at the New Zealand Institute for Plant and Food Research Limited in Auckland since 2009 on diapausing CM cocooned in corrugated cardboard rolls. Following government approval, large numbers of the parasitoids were released into apple growing regions in New Zealand over a period of 5 years from 2012 to 2017. The mass rearing system needed for these releases was managed to avoid bacterial infections and to maintain the fitness of the release insects. Nearly 243,000 adult M. ridens were released into 35 sites across Hawke’s Bay, Gisborne, Nelson, Central Otago, Waikato, Wairarapa and 17 sites in greater Auckland. We selected release sites that were abandoned or poorly managed commercial blocks of apples, or ‘home-garden’ orchards with mature apple, walnut or pear trees, without insecticide sprays. Most releases were made during the period between January and March when there was an abundance of flowering plants (mostly weeds) present, providing a local source of nutrition for the adult parasitoids, and cocooning CM larvae were likely to be present. Mastrus ridens adults were frequently seen at many release sites in late summer providing early evidence of establishment.