Update on the establishment of Thripoctenus javae in New Zealand and new locality records in Bay of Plenty kiwifruit orchards

Abstract

The larval parasitoid, Thripoctenus javae (Hymenoptera: Eulopidae), was introduced into New Zealand in 2001 as a biological control agent for greenhouse thrips, Heliothrips haemorrhoidalis. We have re-evaluated the establishment of T. javae at the release sites from Kerikeri to Gisborne and surveyed kiwifruit orchards in the Bay of Plenty to determine how widespread the parasitoid has become. Release sites were surveyed in autumn 2017 for greenhouse thrips. Foliage samples were collected from numerous host plants, where greenhouse thrips were found, and the number of T. javae pupae on each leaf were recorded. In 2018, a second survey for T. javae was conducted in Bay of Plenty; samples of cryptomeria (Cryptomeria japonica) shelterbelt foliage were collected from 65 kiwifruit orchards. Foliage samples were washed and pupae of T. javae were counted. Thripoctenus javae were recorded at 80% of the original release sites from Kerikeri to Gisborne. The parasitoid was found at all sites in Whangarei and Bay of Plenty, 50% of sites in Kerikeri, 33% of revisited sites in Gisborne as well as the single site in Auckland. No host populations of greenhouse thrips were found at four release sites (Kerikeri =2 and Gisborne =2). In Bay of Plenty, T. javae were found at 32 kiwifruit orchards (49% of the total surveyed). All of these orchards are new locality records for T. javae. The furthest distance T. javae was found from a release site was 55.4 km. The introduction of T. javae into New Zealand has been successful with the parasitoid recorded at 80% of the original release sites after 17 years. Dispersal is evident in the Bay of Plenty where we have detected T. javae at 32 new locations on kiwifruit orchards.