23 October 2001
No evidence has been found to show that Btk, the spray used to eliminate the white –spotted tussock moth from Auckland’s
eastern suburbs in 1996 - 97 had caused health problems to residents in the sprayed area.
This finding is the result of a two-year study by a committee of experts in population health surveillance.
From late November 2001 the organic pesticide Btk will be used again when the next phase of the programme to attempt to
eradicate painted apple moth commences with targeted aerial spraying.
Although Btk is found naturally in the soil and is a commonly used agricultural insecticide in organic production, there
were understandable health concerns in the community, as it had never been used in this way in New Zealand before.
The health report committee examined the health of residents in the sprayed areas for two years after spraying stopped.
They looked at individual, local, regional and national health information. This included investigating residents’
reported health concerns, consultation rates at family doctors in the area, and a review of health data to look at the
size and development of babies at birth.
While the committee found that while there were minor respiratory irritations at the time, there was no evidence of
health problems caused by the spray. Prior to spraying commencing for painted apple moth the Ministry of Agriculture and
Forestry (MAF) proposes to carry out a health monitoring study under the guidance of a health monitoring advisory group.
Spraying for this pest will focus on the edges of the Whau River and associated waterways, and the Waikumete Cemetery,
which are the areas where monitoring indicates the pest population is concentrated.
Ground spraying has already been undertaken at infested sites and this will continue if new sites of infestation are
found. While the moth has been eliminated at some sites, there have been problems in dealing with caterpillars on
vegetation around the edges of waterways where ground spraying has not been able to achieve complete coverage because of
the terrain and height of the vegetation.
The number of sprays necessary will depend on weather conditions during the operation. The sprays will be carried out at
3-4 week intervals. In ideal conditions, six to eight sprays should be necessary.