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Gum leaf skeletoniser long-term management approved

From Biosecurity 47, November 2003.

Cabinet has approved funding for the first two years of a long-term management programme for the gum leaf skeletoniser (Uraba lugens).

The gum leaf skeletoniser is an Australian insect pest, which defoliates a large number of eucalypts. It was first discovered in the Auckland region during August 2001 and, mainly due to its wide distribution, eradication was not pursued.

The basis core of the Long-Term Management (LTM) programme will be research to fill knowledge gaps on the insect, and to control the population within New Zealand. MAF will fund the first two years of the programme and facilitate the longer-term transition.

The LTM programme will include the following four research areas:

1. Population dynamics and impact assessment on host plants

Research into population dynamics will be carried out to establish life cycle, growth and dispersal information. Impact assessment on host plants will identify impacts in the absence of control activities and identify the most susceptible host species. The linkages between the size of the gum leaf skeletoniser population, defoliation impacts and any subsequent effects on tree growth will also be modelled.

2. Biological control

This research will involve selection of parasites and pathogens of the gum leaf skeletoniser identified in Australia. A limited number of them would be tested to determine whether there are any significant impacts on desirable New Zealand fauna such as related native moths. The research programme would progress to the point that forest managers and landowners could seek approval for release of the control agents from the Environmental Risk Management Authority.

3. Suitable insecticides for aerial and ground application

This research will test Btk formulations in conjunction with wetting or penetrative agents to increase their effectiveness. It will also identify non-Btk formulations suitable for use in non-urban areas or in closely controlled urban conditions. It will then be up to forest managers and landowners to seek and fund any necessary label changes.

4. Monitoring and mass trapping

Using the synthetic pheromone developed for the gum leaf skeletoniser as a lure in a trapping programme is an effective means of monitoring the
population. The pheromone developed for gum leaf skeletoniser requires further refinement and testing to establish its effectiveness and to enable the accurate interpretation of trap catch results. Once this is achieved it could be used to monitor the population and to develop a mass trapping technique for use by forest managers and landowners. Mass trapping would provide low-cost control for those who prefer not to use insecticides or for use in sensitive areas.

Technology transfer

To assist in the transition to long-term pest management for forest managers and landowners, the results of this research programme will be presented as leaflets, handbooks, web pages and, in the case of the predictive model, a user-friendly computer interface. Educational field-days involving key researchers will be conducted to assist in the uptake of this information. In addition, a controlled area will be maintained to help slow the spread of the Auckland gum leaf skeletoniser population.

Mark Ross, National Adviser Pest Surveillance and Response, Forest Biosecurity



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