Stage 4

Background

The new Stage 4 project, “Biocontrol Research for Weed Management – 2024–2029,” commenced in July 2025 and builds on a decade-long collaboration between CSIRO and the NSW Environmental Trust (Stages 1-3). The aim of Stage 4 is to extend this work for another five years, focusing on testing the safety and efficacy of plant pathogens and herbivores as biocontrol agents for priority invasive environmental weeds in Australia, and supporting the mass-rearing and release of approved agents in partnership with stakeholders.

Strategic focus

The new Stage 4 project includes a strategic emphasis on robust monitoring and evaluation. Monitoring will continue to track agent establishment, weed suppression, and ecosystem recovery, building on successful approaches from previous stages.

Additionally, Stage 4 explicitly incorporates activities dedicated to Indigenous engagement, aiming to co-design and deliver research in collaboration with Indigenous communities across NSW. This aligns with the Trust’s strategy of prioritising healthy Country and valuing Indigenous peoples’ traditional knowledge and connection to land, as well as CSIRO’s Reconciliation Action Plan.

Implementation Plan No. 1

Giant reed (Arundo donax)

The project will develop and submit a nomination for giant reed as a candidate for biocontrol research, including stakeholder consultation to address conflicts of interest and a phylogenetic analysis to inform host testing. This foundational work will set the stage for future research on suitable biocontrol agents, with the gall wasp Tetramesa romana identified as a promising candidate.

Hudson pear (Cylindropuntia pallida)

Ongoing mass-rearing and release of the cochineal insect Dactylopius tomentosus (lineage ‘californica var. parkeri‘) will be conducted at new infestations in western NSW, with a focus on sites unsuitable for chemical control. The project will establish a new long-term monitoring site at Stephen’s Creek near Broken Hill to track agent establishment, dispersal, and early impacts using both ground surveys and drone imagery.

This research is being delivered by NSW DPIRD’s Weed Research Unit. For further details, contact team leader Andrew McConnachie, andrew.mcconnachie@dpird.nsw.gov.au.

Wandering trad (Tradescantia fluminensis)

The leaf-smut fungus Kordyana brasiliensis will be further distributed to high conservation value areas where it has not previously been released, with continued monitoring at existing experimental plots. The project will also develop integrated management guidelines for combining the fungus with other control methods and support community engagement through workshops and targeted releases.

https://research.csiro.au/wandering-trad/current-research/

Mother-of-millions (Kalanchoe delagoensis and K. x houghtonii):

The focus is on maintaining cultures of the stem-boring weevil Osphilia tenuipes, preparing a release application, and consulting with stakeholders to address potential conflicts of interest. Ongoing monitoring at long-term pre-release field sites will continue to inform the agent’s suitability and impact.

This research is being delivered by NSW DPIRD’s Weed Research Unit. For further details, contact team leader Andrew McConnachie, andrew.mcconnachie@dpird.nsw.gov.au.

Ox-eye daisy (Leucanthemum vulgare)

Cultures of two candidate agents, the rhizome-feeding moth Dichrorampha aeratana and the root-feeding weevil Cyphocleonus trisulcatus, will be maintained in both Australia and Switzerland. The project will prepare and submit release applications for these agents and continue monitoring at long-term pre-release field sites to support regulatory approval.

This research is being delivered by NSW DPIRD’s Weed Research Unit. For further details, contact team leader Andrew McConnachie, andrew.mcconnachie@dpird.nsw.gov.au.

Leafy elodea (Egeria densa)

The leaf-mining fly Hydrellia egeriae will undergo further Tier II host-specificity testing in CSIRO containment, expanding the range of non-target species tested. The project will also develop a phylogenetic analysis to inform host test lists, with the aim of generating sufficient evidence for a future release application.

https://research.csiro.au/weed-biocontrol/leafy-elodea-biological-control/

Small-leaf privet (Ligustrum sinense)

The privet lace bug Leptoypha hospita will be imported from New Zealand and maintained in containment for additional Tier I host-specificity testing, including multi-generational and multiple-choice trials. This work will clarify the risk to native privet species and inform decisions on progressing to more advanced testing or release applications.

This research is being delivered by NSW DPIRD’s Weed Research Unit. For further details, contact team leader Andrew McConnachie, andrew.mcconnachie@dpird.nsw.gov.au.

Monitoring and evaluation network

Stage 4 IP1 includes the creation of a weed biocontrol monitoring and evaluation network, which will use and enhance the Atlas of Living Australia (ALA) Biocontrol Hub for standardised data collection and reporting. A Roadmap will be developed to guide the network’s implementation, and data analysis workflows will be trialed with historical datasets, laying the groundwork for long-term, stakeholder-driven monitoring and improved programme effectiveness across NSW.