Response to Meriel Watts article "MAF bungles the biosecurity in West Auckland"

14 January 2002

by Dr Ruth Frampton, Director Forest Biosecurity,
Ministry of Agriculture and Forestry

MAF's aerial spraying on track to knock out painted apple moth

It is extraordinary that a project which hasn't even got of the ground yet (literally), is being pre-judged and condemned by some people purporting to represent the local community.

The Ministry of Agriculture and Forestry (MAF) plans to start targeted aerial spraying parts of some west Auckland suburbs later this month. The project has been supported twice by resident surveys, applauded by environmental groups, ratified by the technical advisory group and reviewed and endorsed by two independent experts - from the USA and New Zealand.

The painted apple moth eradication project is being compared with the white-spotted tussock moth operation that took place six years ago in the eastern suburbs of Auckland. There are marked differences. The pest itself behaves differently. The spray, Foray 48B, is much more effective against painted apple moth. Technology advances mean spraying can now be carried out with pinpoint accuracy thanks to Global Positioning Systems technology. The area to be sprayed is different and attitudes have changed. Waitakere residents live in Eco City. They are concerned about their unique environment and rightly so. It would be irresponsible and unacceptable to spray unnecessarily.

Despite reports to the contrary, the majority of residents of the suburbs to be sprayed still support eradication of the painted apple moth. A survey of 600 residents in November and December found that 73% of respondents thought it very important or important to undertake eradication. Overall 62% strongly agree or agree with the proposed targeted spraying.

Timing to start target aerial spraying is fortuitous. The latest moth trap catches which track the spread of male moths show a marked drop in the numbers. This means the pest is "between generations" - an optimum time to spray, given that a good proportion of the population will be in the caterpillar stage.

Background

Painted apple moth (PAM) was found in Glendene, Auckland in May 1999 and was later discovered in Avondale, Glen Eden, Kelston, Titirangi and Mt Wellington. MAF recognised how serious the impacts of this pest could be - more so than white-spotted tussock moth. Eradication was a priority, supported by the early establishment of a Technical Advisory Group, which included several of the scientists advising on the white-spotted tussock moth programme.

PAM is native to Australia where it is a sporadic pest. In New Zealand, the moth threatens forestry and horticulture, as well as the natural environment. The caterpillars are indiscriminate feeders. While they prefer wattles and acacia trees, they have also been found feeding on three native species: kowhai, karaka, and mountain ribbonwood. If PAM were to become widespread throughout New Zealand, the economic impact has been estimated to be at least $48 million over 20 years (NPV).

In 1996-97, Operation Ever Green used blanket spraying with a DC-6 aircraft to eradicate white-spotted tussock moth in east Auckland. Unlike the white-spotted tussock moth, the female painted apple moth does not fly, and this limits its natural dispersal. This encouraged MAF to adopt a conservative and responsible approach to pursuing the moth's eradication which would minimise disruption to the community without compromising the chances of eradication.

In May 2001 MAF's approach to the PAM incursion was reviewed by an entomologist from the USDA Forest Service and an independent New Zealand biosecurity consultant. The review found that the "overall PAM eradication strategy appears to have been appropriate" and prospects for eradicating the insect still look good. The forest industry and other stakeholders have applauded MAF's quick response to the recommendations in the review report - these included developing a plan for the use of targeted aerial spraying as an option for future control.

What's been done so far

Targeted aerial spraying is part of a much wider programme to eradicate the moth.

Visual property-by-property surveys have been conducted every 7-8 weeks to find out where the pest is. Infested vegetation is ground sprayed with Decis (a synthetic pyrethroid insecticide) and regularly monitored for any signs of reinfestation. When sufficient supplies of Foray 48B are available, future ground spraying will be carried out with that spray - as requested by some community group members.

Restrictions have been put in place to prevent removal of garden waste from infested properties and neighbouring properties, parks and reserves. Free, safe disposal of garden waste is being offered to over 20,000 west Auckland properties.

Live moth trapping started in December 2000 and now over 600 traps cover west Auckland through to Mt Wellington. Research is still underway to find a synthetic pheromone (a sex attractant) to replace live female moths used in traps. Two teams are working on this but neither has yet produced a result. Pheromones can be an important part of monitoring the progress of eradication programmes - but not an eradication method.

In some hard-to-reach areas around the margins of the Whau River and its associated waterways, Traherne Island, Waikumete Cemetery and Avondale Peninsula, ground based controls have proved ineffective because of the terrain and height of trees. These are the areas targeted for aerial spraying.

A BK 117 helicopter will be used to carry out the spraying. In favourable weather conditions, six to eight sprays should be adequate. Spraying is scheduled to start on 19 January 2002, and one spray will take about seven hours to complete. If weather conditions are not right, the spraying will continue on the next good day.

The spray to be used is Foray 48B, a formulation of Bacillus thuringiensis kurstaki (Btk), a naturally occurring soil bacterium. This is the same formulation that was used in Operation Ever Green. Btk kills caterpillars. It does not harm animals or people.

Healthy people are not at risk

There's been a lot of attention and hype about health risks of Btk and this has caused unnecessary concern among residents. A health risk assessment, carried out by the Auckland District Health Board's Public Health Protection division recently, gave Btk a clean bill of health. The assessment said it did not expect any significant health effects to occur from the spray. This supported the findings of an earlier study carried out during Operation Ever Green which found there was no evidence that residents exposed to the spray suffered adverse health effects or chronic health problems. The study did report some minor respiratory irritations during the spraying and because of this an independent health monitoring and support programme has been established for the PAM project. A health register has been set up and everyone on that list will be contacted by a doctor (and by MAF) before spraying starts. MAF has also arranged for a free local consultation service involving a number of doctors, practice nurses and environmental health specialists. By appointment, residents who think they may have been adversely affected by the spray, can take advantage of this service.

Pest eradication operations are notoriously difficult, and there is no guarantee of success. The PAM project is complex, involving three local authorities, numerous government departments, several research institutions, and hundreds of people who could be inconvenienced by the spraying. Aerial spraying is not an ideal solution but it is necessary if we are to protect New Zealand's environmental, forestry and environmental interests. We accept that people are concerned, and want to assist them as much as we can. Any person with queries or concerns about the programme can call the painted apple moth 0800 number, 0800 969696, or visit our website - www.maf.govt.nz/painted-apple-moth.

  

 

Last Updated: 06 October 2010

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