Government funding has been approved for what Northland Regional Council describes as a potentially world-first attempt to use insects to tackle wild ginger infestations.

NRC applied to the Ministry for Primary Industries' (MPI) Sustainable Farming Fund last year for $464,470 to research wild ginger biocontrol agents in the Sikkim region of northern India until mid-2021. Council biosecurity manager Don McKenzie said last week that the funding had been approved, and the almost $900,000 project would officially begin in August.

Co-funding from the regional council and partner organisations including Hancock Forest Managers, Summit Forests, Department of Conservation, Northland's three district councils, Auckland Council, Landcare Research and National Biocontrol Collective would require $897,130 to enable the group and international collaborators to fully research the viability of several potential biocontrol agents identified in India.

These include a large weevil, a fly and a beetle, covering the cost of their import and distribution if suitable.

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Cr Mike Finlayson (Te Hiku), a long-time advocate for controlling wild ginger, said the species had reached plague proportions in Northland. Despite the best efforts of many people over a number of years, it now occupied more than 5000ha in state and privately-owned forests.

"It has got to the point where it's now costing the regional economy an estimated $3 million to $5 million due to the loss of productive land alone," he said.

Mr McKenzie said the best-studied prospective biocontrol agents so far were a fly (Merochlorops cf. dimorphus), whose larvae mined wild ginger stems, and a large weevil (Metaprodioctes cf. trilineatus) that fed on all parts of the plant.

However, the project would also provide key information about other insects that could be further developed for biocontrol of wild ginger. Cr Finlayson said while biocontrol programmes had existed for around 90 years, wild ginger was a novel target for biocontrol internationally.

"This project will develop never-before used, or studied insects as biocontrol agents for wild ginger," he said.

Importing biocontrol agents could also open up other pathways internationally, with New Zealand possibly supplying successful agents to other regions battling invasive ginger, such as Hawaii and parts of Queensland.

Mr McKenzie said the project would build on work supported by the National Biocontrol Collective (NBC), made up of regional councils nationwide and Department of Conservation.

"The NBC supports research to develop biocontrol for up to a dozen weeds targets annually, so the funds available for each target are extremely modest," he said.

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Both the fly and the weevil looked highly promising, and were likely to be sufficiently host-specific for release in New Zealand, although further testing was needed to confirm that, and to develop mass rearing and release techniques.

Research funded by NBC had also identified several more insects, about which little was known that were worth investigating as future wild ginger biocontrols.

The project will be carried out by Landcare Research with help from UK-based collaborator the Centre for Agriculture and Bioscience International (CABI) following the usual steps to develop biocontrol for weeds in accordance with international best practice.

The project will support:

* Surveys in India to find, collect and identify prospective biocontrol agents;
* Maintaining colonies of promising species, and studies of their lifecycles and damage potential;
* Determination of the host range (safety) of promising species;
* Preparing an application to the Environment Protection Authority to release two suitable agents;
* Importing those agents to a Landcare Research containment facility, until MPI grants approval to release them;
* Developing mass rearing methods and eventual release around Northland and elsewhere;
* Assessment of the success and initial impact of the ginger biocontrol agents.

Cr Finlayson said Northland was already home to a surprising number of biocontrol agents, including beetles that fed on tradescantia, fungi and rusts that collectively attacked a variety of pest plants and insects including tropical grass webworm, mistflower, gorse, ragwort and woolly nightshade.

"Before any biocontrol can be released in New Zealand it's subjected to extensive and lengthy research to make sure it's host-specific and won't target other species, and any proposed biocontrol for wild ginger will be very well-researched," he said.

¦More information about the regional council's biocontrol programme and in pest control is at www.nrc.govt.nz/nasties