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Painted apple moth eradication programme gearing up

from Biosecurity Issue 32, December 2001.

MAF Biosecurity continues to pursue the eradication of painted apple moth from the suburbs of Auckland.

Where is it?

Painted apple moth (PAM) was found in Glendene, Auckland, in May 1999 and was later discovered in the neighbouring west Auckland suburbs of Avondale, Glen Eden, Kelston and Titirangi. In addition, the moth has been detected in Mt Wellington, some 15 kilometres away. The distance between the two infestation locations is thought to rule out spread by natural dispersal (Biosecurity 21:15).

Why attempt eradication?

Painted apple moth is a native of Australia where it is a sporadic pest, partly because population levels are affected by pesticides applied to trees to control other pests. In New Zealand the moth threatens forestry and horticulture industries, as well as our outdoor environment, and there are few natural controls.

Painted apple moth feeds on many different types of plants but particularly likes wattles and acacia trees. It can feed on young pine trees (up to about eight years), affecting their growth and has also been found feeding on kowhai, mountain ribbonwood and karaka.

If it spread, the economic cost to the country is estimated to be at least $48 million over 20 years (NPV).

A unique plan of attack

In 1996-97, Operation Ever Green used blanket aerial spraying by a DC6 aircraft to eliminate white-spotted tussock moth from east Auckland. While painted apple moth is a relative of white-spotted tussock moth, there are several important differences which have encouraged MAF to adopt a different approach to pursuing its eradication.

Unlike the white-spotted tussock moth, the female painted apple moth does not fly, limiting its natural dispersal. Newly hatched caterpillars can produce silken threads, which may be caught in the wind allowing the caterpillars to “balloon” onto other foliage. The pest can also be spread by piggybacking on removed vegetation or by the caterpillar crawling amongst trees.

Taking the moth’s habits into consideration, MAF has adopted a conservative approach to the painted apple moth response, opting to balance disruption to the community without compromising the chances of eradication.

So far, so good

The painted apple moth infestation in Auckland has been controlled by ground spraying and the removal of host plant material. An ongoing comprehensive trapping programme and visual property-by-property surveys have been conducted every 6-7 weeks to define where the pest is. Where caterpillars are found, the vegetation is ground sprayed with Decis (a synthetic pyrethroid insecticide) and the property is subsequently inspected weekly to monitor the effectiveness of the treatment and to check for any signs of reinfestation.

Restrictions are in place to prevent removal of garden waste from properties on which painted apple moth has been found during visual searches. Similar restrictions are also placed on movement of material from neighbouring properties,parks and reserves and from the Waikumete Cemetery.

But when the going gets tough…

Trapping and visual inspections have revealed the ongoing presence of painted apple moth in areas around the edges of the Whau River and associated waterways, on Traherne Island and in the Waikumete Cemetery. These areas are often inaccessible to ground spray because of the terrain or the height of the trees.

The tough get going…

MAF is currently making arrangements to conduct targeted aerial spraying in those areas where control has proved ineffective due to the inability to reach the pest with ground spray.

A twin-engined helicopter will be used. It is expected spraying will occur between 5am and 7am. The wind is calmest at this time, which will help minimise spray drift. A 20-30 metre strip will be sprayed along the edges of the Whau River and associated waterways. This spray strip may need to be extended if control is not achieved. In favourable weather conditions six to eight sprays that would be used to replace the live should be adequate, although additional female moths currently used in the spraying may be necessary if the spray is traps. The intricacies of identifying a affected by rain or is rendered ineffective synthetic pheromone have for any reason. 

The spray to be used is Foray 48B, a formulation of Bacillus thuringiensis kurstaki (Btk). This is an organic insecticide, which was used during Operation Ever Green. It is specific to caterpillars and does not harm animals, fish or people.

Health concerns are being addressed

An independent health study was undertaken as part of Operation Ever Green. No evidence of adverse health effects in residents was found, other than minor short-term respiratory and skin complaints. A new independent health monitoring and support programme is being put in place in conjunction with the painted apple moth operation.

An integral part of this programme is the establishment of a health register for residents with particular health concerns. A doctor will individually contact registered residents to discuss their concerns and any precautions they should take. MAF has undertaken to advise those people on the register before each spray is conducted.

In addition, the Auckland Health Board’s Medical Officer of Health has commissioned an independent health risk assessment which will include recommendations on precautions residents may wish to take to avoid any effects of the spray.

An expensive exercise

The programme is expected to cost between $7.908 million and $11.122 million over three years depending on the number of aerial applications required, the area to be sprayed and the time it takes to develop a synthetic pheromone-based attractant.

Science stepped up

Research is being undertaken by two groups of researchers to identify a synthetic pheromone that would be used to replace the live female moths currently used in the traps. The intricacies of identifying a synthetic pheromone have protracted this task, and development has taken longer than originally expected (Biosecurity 22:19). When successfully developed, the use of a synthetic pheromone in traps cannot be considered to be an eradication measure, but rather a monitoring tool.

Advisory groups

Managing an exotic pest and disease response is an involved process and it is necessary to convene various advisory groups to ensure all bases are covered. MAF is supported by the following groups:

  • a technical advisory group provides expert technical advice on the programme. Members have technical and operational expertise.
  • a health steering group has guided the design of the health monitoring and support programme to begin in conjunction with the aerial part of the operation.
  • an interdepartmental officials group has been convened to coordinate the activities of the affected government departments. It includes representation from the Treasury, Department of Conservation, Ministry for the Environment, Civil Aviation Authority, Occupational Safety and Health, Police, Transit NZ, Ministry of Health and Auckland Regional Council.
  • a community advisory group includes representation from interest groups such as the Asthma Society and community boards as well as local residents

Environmental/Maori impact assessment

An independent environmental impact assessment was completed at the time of Operation Ever Green and this is now being updated to cover the waterways in west Auckland. Impacts on Maori are also being investigated – the gathering of kaimoana, for instance. Local iwi have been consulted but no particular issues have come to light so far.

Public awareness research

A telephone survey of 600 residents in late August/September showed 62 percent of respondents were aware of painted apple moth, 86 percent agreed it was important to attempt eradication and 70 percent agreed with targeted aerial spraying. Since this time, there has been increasing opposition to the programme in the media and another wave of research is being undertaken to gauge community feelings more accurately.


An extensive communications programme is planned to support the response operation. An Auckland public relations company, Consultus, has been recently contracted to provide communications resources at the operational headquarters being set up in west Auckland.

Regular communication with Waitakere City Council and Auckland City Council is crucial to the programme.

Residents in the areas affected by the spraying will be notified at least two weeks before each spray. Media, especially radio, will be used to update residents on activities – such as any delays in planned spraying because of weather conditions.
0800 96 96 96

Ruth Frampton, Director Forest Biosecurity, MAF



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