September 22, 2000
The Environmental Risk Management Authority has just given the Auckland Regional Council (ARC) approval to import and release the mist flower gall fly (Procecidochares alani) to biologically control mist flower (Ageratina riparia) which is threatening to squeeze out native trees and plants in the northern regions of the country. Mist flower is a low growing scrambling perennial weed which is found on the edges of forests or in clearings, along the banks of streams, wetlands, roadsides and rough pasture. The plants grow quickly and on average a mature plant can produce up to 100,000 seeds annually, making the plants difficult to control.
In its application. the ARC stated that the gall fly, with a wing span of just 8mm will lays its eggs only in the mist flower plants and the larvae will attack the stems of the plants reducing its growth and thus allowing the native species to regenerate. They say that the mist flower gall fly will complement another biological control agent, the fungus Entyloma ageratinae which was imported in 1998 to also try and control the mist flower.
The Environmental Risk Management Authority which controls the introduction of new plants and animals, including genetically modified organisms and hazardous substances into New Zealand conducted a public hearing into the ARC's application. It received a total of 14 submissions, of which 10 supported the introduction of the gall fly, two were against it and two were neutral in their views. The Authority received a evaluation and a review report from ERMA New Zealand staff and also sought outside independent advice as part of the decision making process. In addition to this information, extensive laboratory trials were carried out by Landcare Research on behalf of the ARC to make sure that the gall fly would attack only mist flower and not other species of plants - especially natives. These trials were approved by the Authority in 1998.
In announcing its decision today, the Authority noted that mist flower was a serious threat to biodiversity and indigenous ecosystems and that the mist flower gall fly would have no significant adverse environmental impacts on any other plants and in particular native flora and fauna. It said that the risks posed by mist flower to native and valued flora and the intrinsic value of ecosystems in New Zealand would have greater impact on Maori taonga than the introduction of the gall fly into the environment for the biological control mist flower. The Authority acknowledged a general opposition by some Maori and other parties to the introduction of foreign species in principle, But in this case it was considered that the potential widespread environmental benefits of controlling mist flower outweighed the potential adverse effects of introducing the gall fly.
The Chief Executive of ERMA New Zealand Dr Bas Walker says this is the first time since the introduction of the 1996 HSNO Act that the Authority has approved the importation and release of a biological control agent to combat a weed problem. Other recent approvals related to the importation of parasites to control insects. Dr Walker says biological control agents are widely used throughout New Zealand to control a variety of weedy plants including gorse and ragwort.
For more information contact:
Bas Walker
Chief Executive
Ph 04 4738426