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The application to introduce Aceria vitalbae as a biological control agent for old man’s beard was approved by EPA in October 2018. This mite galls the leaves of old man’s beard.

Old man's beard

The decision and all associated documents can be found on EPA's website.

Background

This application will be submitted by Horizons Regional Council, acting on behalf of the National Biocontrol Collective, a consortium of regional councils and the Department of Conservation. The Collective funds the development of weed biocontrol programmes in New Zealand. Landcare Research is the science provider for this development. Landcare Research has contracted Richard Hill & Associates to prepare the application and to manage the application process on behalf of Horizons Regional Council, including pre-application consultation with EPA and with Māori and other stakeholders.

This will be the fourth control agent to be introduced for old man’s beard control, but the first under the EPA regulatory regime. The disease Phoma clematidina was introduced in 1996. It initially caused much damage but is thought to have since died out. The old man’s beard sawfly was introduced in 1997. It has recently been detected for the first at just one site. Its future is uncertain.  The old man’s beard leaf-mining fly was introduced in 1996 and is now abundant nationwide. Alone it is not exerting sufficient damage to reduce the pest status of old man’s beard. Another agent that attacks the stems is being studied.

Old man’s beard is a vine that grows over and overtops trees, shrubs and other vegetation. It forms a thick blanket that blocks light from the plants underneath, eventually killing them. Native bush is particularly vulnerable to old man’s beard and large areas can quickly become dominated by this pest. This vine can smother plants to the highest canopy, and prevents the establishment of native plant seedlings. It moves readily into established forest over the canopy by layering.

For more information on old man’s beard see:

Identification and assessment of risks, costs and benefits

The potential risks, costs and benefits of the proposed introduction to New Zealand of Aceria vitalbae and the possible reduction in the abundance and vigour of old man’s beard have been identified in previous applications and by consultation with stakeholders. The significant effects identified will be presented here once available:

Old man’s beard has no beneficial environmental or economic attributes. Potential benefits of biological control would mitigate the adverse effects described above. The key possible adverse effects of introducing the mite will be addressed fully in the application:

  • the risk of direct damage to valued garden ornamentals
  • the risk of direct damage to native plants
  • indirect effects on flora and fauna as a result of disruption of ecological relationships

There is rich flora of native and ornamental Clematis species to be protected in New Zealand. Aceria species like the leaf-curling mite are known to be highly host-specific and this agent is expected to feed on old man’s beard alone. However, testing is not yet completed. If results permit, the application will be prepared, and will present evidence to show that populations of the leaf-curling mite will not establish on native and desirable ornamental plants. It will examine whether incidental damage to these plants is likely when infestations of old man’s beard are nearby.

Because the leaf-curling mite will have a narrow host range or a single host, population densities capable of interacting significantly with other plants or animals will only be found in close proximity to old man’s beard. As a result, no significant disturbance of ecological relationships is expected in New Zealand. The presence of old man’s beard itself massively modifies natural interactions between species, and any reduction in the weed will help reverse those impacts.

Pre-application consultation with Iwi

The application will address issues identified by Māori via four pathways:

  1. The members of the EPA 's national network Te Herenga will be contacted in May 2017, and invited to enter dialogue on the proposal. The message to Te Herenga will describe how the applicant intends to assess the risks, costs and benefits associated with the proposed introductions. Members will be invited to identify any issues that they would like to be addressed in the application.  Any responses by Te Herenga members specifically related to the proposed introduction of the omb mite will be summarised here at the end of the consultation period:

Members of Te Herenga will also be informed by EPA when the application is open for public submission, and will be able to comment on how the applicant has addressed issues raised during consultation.

  1. Horizons Regional Council will circulate information and an invitation to dialogue to its own networks of iwi, hapū and marae
  2. Consultation has been carried out on many previous applications to introduce biocontrol agents for weeds.  The common issues raised by these previous consultations will be presented and addressed in this application.
  3. EPA convened a reference group from Te Herenga to meet and discuss the issues surrounding the proposed applications.  The issues raised by the reference group will be taken into account during the preparation of the application.

Pre-application consultation with other organisations

Other organisations consulted were:

  • New Zealand Plant Producers Incorporated
  • Regional Councils
  • Federated Farmers
  • Royal Forest and Bird Protection Society of New Zealand
  • Department of Conservation staff
  • QEII National Trust
  • NZ Landcare Trust

Summary of responses:

Key documents

Reports on host-range determination

Safety issues are paramount in the minds of biocontrol of weeds researchers. Researchers rigorously test all proposed agents to assess the risk of damage to non-target plants. A set of procedures helps researchers choose a suitable shortlist of test plants, and this methodology is now well-accepted internationally (Wapshere, 1974). The technique is under constant review to update best practice (e.g. Sheppard et al., 2005; Briese, 2005).

The results of host range testing conducted in Serbia and New Zealand on old man’s beard leaf-curling mite will be fully discussed in the application. Reports compiled by Landcare Research that discusses host plant selection, and the test results from Serbia and New Zealand. This report can be found here once it is available.:

The unpublished reports will be peer reviewed and that review will be provided to EPA.

Cited references

Wapshere AJ (1974) A strategy for evaluating the safety or organisms for biological weed control. Annals of Applied Biology 77: 201–211.

Briese D (2005) Translating host-specificity test results into the real world: The need to harmonize the yin and yang of current testing procedures. Biological Control 35: 208–214.

Sheppard AW, Heard TA, van Klinken RD (2005) Scientific advances in the analysis of direct risks of weed biological control agents to non-target plants. Biological Control 35: 215–226.