Distribution of Dock Moth in Victoria

Summary

Aims

1. Develop a distribution network for the dock clearwing moth in Victoria.

2. Train and assist landholders in the identification of suitable release sites as part of their management plans and in the management of "nursery sites".

3. Establish five new release demonstration sites each year in 1996-97, 1997-98, 1998-99.

4. Monitor insect establishment for a period of two years after release.

5. Maintain the landholder network for the duration of the project. Background In August 1996 Meat Research Corporation reached agreement with Keith Turnbull Research Institute (KTRI) to distribute the dock clearwing moth in Victoria for biological control of large-rooted Rumex species.

The dock moth has previously been called Chamaesphecia doryliformis (Ochsenheimer), but should be referred to as Syansphecia doryliformis (Ochsenheimer). The agent had previously been released in Victoria under two separate projects:

(1) as neonate larvae from January 1991 to 1993 at 6 sites by officers of the Victorian Department of Agriculture and 1 site by a landholder using material supplied by New South Wales Agriculture, and

(2) using egg sticks from 1994 to 1996 at several sites in the St Helens area of south-west Victoria by the St Helens Shelterbelters landcare group. The St Helens Shelterbelters made further releases in November 1996.

From December 1996 eggs were also supplied directly to Victorian landholders by Agriculture Western Australia. This report provides data on new releases during the 1998-99 season, monitoring of release sites, summary data of all Victorian releases, summary data of inoculation success and survival/dispersal success for all sites with KTRI involvement and an overview of the whole subproject.

It was initially doubted that the agent would survive in much of Victoria due to it's supposed poor climatic adaptation and results of releases of larvae during 1991-93. Dr John Scott's climatic matching (Biological Control of Dock Workshop, Perth., August 1996) indicated that only small areas of the Murray Valley fitted the strict Mediterranean climate requirements of S. doryliformis. Site inspections and other investigations undertaken in association with this project produced no evidence that the agent had survived at any of the seven sites where larvae were released in 1991-93. However the agent has subsequently established in southern, central and northern Victoria (progeny from the first season of releases under this project in summer 1996-97) and is dispersing. Impact on the target weed appears to be small at many of the sites where it survives, but dock densities have been reduced in the immediate release areas by 90% at at least two sites (Tynong North and Timor). A proper field based evaluation of Victorian releases needs to be undertaken after the agent has had a longer opportunity to consolidate its presence in areas where it has survived and is dispersing. It is recommended that Meat and Livestock Australia fund a project in 2002-03 to monitor Victorian release sites and assess dispersal. The second dock moth, Bembecia chrysidiformis, is thought to be better suited to temperate southern Australia than S. doryliformis and is the subject of a separate application to MLA for funds.