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14 January 2002
by Dr Ruth Frampton, Director Forest Biosecurity,
Ministry of Agriculture and Forestry
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
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
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.
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
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.
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.
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.