Novel release method proves successful: The gum leaf skeletoniser parasitoid Cotesia urabae establishes in two new locations

Abstract

The Australian braconid wasp Cotesia urabae was first released in New Zealand in 2011, as a biological control agent for the gum leaf skeletoniser Uraba lugens (Lepidoptera: Nolidae). The larvae of this moth predominantly attack Eucalyptus spp. (Class: Symphyomyrtus) and, since its predicted future geographic range is extensive, there is concern it could become a serious pest of eucalypt plantations in New Zealand. Initial releases of C. urabae using adult parasitoids were made in Auckland at three separate sites between January and June 2011. Cotesia urabae established at each site and preliminary monitoring has revealed that the wasps have naturally dispersed to six other sites, ranging up to 6 km from an initial release site. In January 2012, C. urabae were released in Whangarei and Tauranga, trialling a novel method using parasitoid-attacked host larvae, rather than adult parasitoids. This method proved to be successful, with establishment now confirmed in both of these locations, and also provided greater flexibility. The two latest releases were made using the same method in Nelson (October 2013) and Napier (February 2014), but it is not yet known if the parasitoid has successfully established in these locations.