A tiny wasp that attacks a major New Zealand insect pest is set to have a big impact on the citrus and avocado
industries. A decision today (23 June) to allow importation and release of the wasp comes after more than five years
work by scientists at HortResearch.
Growers have said that greenhouse thrips cost about $6.25m a year in either damage to commercial citrus and avocado
crops, or in control costs. Until now, they have had no alternative to broad-spectrum insecticides.
The decision by the Environmental Risk Management Authority to release Thripobius semiluteus, a pinhead-sized parasitoid
wasp species, will mean reduced costs for growers, less fruit damage, the opportunity to expand organic production and
the chance to get high value premiums for fruit.
Philippa Stevens, who headed the research team evaluating the wasp for the growers, said: "This parasitoid is the only
way that use of broad spectrum insecticides can be reduced for citrus and avocados. It is a very encouraging result for
the future of biological control research in New Zealand."
The minute wasp - adults are only 0.6mm long - lay their eggs inside greenhouse thrips, eventually killing them.
Non-monetary benefits from introducing the wasp include decreased environmental contamination through insecticide use.
Thrips also cause damage to ornamental plant species, and the wasp could also eventually be marketed to urban gardeners.
Now HortResearch will import the wasps from California, and after a month in quarantine, scientists will begin to breed
up numbers ready for release early next year.
Rick Curtis, chairman of New Zealand Citrus Growers Inc said: "We need to reduce our reliance on traditional
insecticides and this biocontrol provides us with a tool to move into more competitive growing.
"We went through the lengthy and careful system required by ERMA, and Philippa Stevens' work provided sufficient
evidence to satisfy their concerns."
Dr Jonathan Cutting, Chief Executive of the Avocado Industry Council, was delighted with the ERMA process and the
outcome.
"Until now we had to use insecticides to control thrips and this had a negative impact on our AvoGreen programme, as
there are no soft spray options. I am optimistic that the wasps will be an alternative and we will continue to work with
HortResearch to evaluate their impact. I am also thrilled at the way the ERMA process has worked for us."
ERMA approved the importation and release of Thripobius semiluteus after a lengthy hearing and consultation process. The
application was lodged by the New Zealand Citrus Growers Inc and the Avocado Industry Council, supported by
HortResearch. It was opposed by the Department of Conservation and the Royal Forest and Bird Protection Society.
The decision is the first on the release of new organisms since the Hazardous Substances and New Organisms Act took
effect in July 1998.
For further information contact: Philippa Stevens HortResearch Mt Albert Research Centre Auckland Tel: 09 815 8200 Fax:
09 815 4201
Deborah Potter Communications Manager HortResearch Private Bag 11 030 Palmerston North Tel: 06 351 7000 Ext 7726 Fax: 06
351 7038 Mobile: 025 588 484