Wasp to defeat 'skeletoniser'
The gum-leaf skeletoniser is a moth with
the potential to defoliate eucalyptus
planations and ornamental eucalyptus
grown for shade and shelter.
Image: iStockphoto

A tiny Tasmanian parasitic wasp, Cotesia urabae, is going to be released by scientists in New Zealand in 2011 in an attempt to tackle an Australian insect that is ravaging their eucalypt trees.

Dr Geoff Allen, a Senior Lecturer in Entomology from the UTAS School of Agricultural Science and the Tasmanian Institute of Agricultural Research (TIAR), and his New Zealand research colleagues have received approval to use the parasitic wasp to combat the gum-leaf skeletoniser (Uraba lugens) - an Australian moth that has the potential to defoliate Eucalyptus plantations as well as ornamental Eucalyptus grown for shade and shelter throughout New Zealand.

“People get a bit nervous when you start talking about wasps because they usually think of the European wasp,” Dr Allen said. “But Cotesia urabae is only about 3 millimetres long and is harmless to humans. It’s an effective control against the gum-leaf skeletoniser because the wasp lays its egg inside the caterpillar, and when ready to pupate the larva eats its way out and kills the caterpillar.”

Since 2003, Dr Allen has been working as a research advisor on an international biocontrol program (funded by New Zealand's Sustainable Farming Fund) to combat the gum-leaf skeletoniser in New Zealand.

An economic impact assessment conducted for New Zealand estimated the potential cost of gum-leaf skeletoniser at NZ$100–$142 million. There is also a significant concern for public health from rashes resulting from contact with this insect.

Dr Allen’s role involved consultation over the selection of potential biocontrol agents, the collection of biocontrol agents in Tasmania and interstate, rearing protocols for biological control agents and their hosts, and research on biocontrol agent specificity in Tasmania.

In late 2008, Dr Lisa Berndt, from the New Zealand forestry research organisation Scion, came to Tasmania to finalise key research needs prior to submission of the release application.

The following year this also resulted in the development of an honours project, funded by New Zealand. Undertaken by Raylea Parr, the honours project examined the key aspects of the biology of the skeletoniser and the proposed biocontrol agent in Tasmania.

Approval for the release was provided by the New Zealand Environmental Risk Management Authority (ERMA). If the wasp is able to become established, its release is predicted to make a significant impact.

Editor's Note: Original news release can be found here.