Stage 3

Stage 3 is funded across five annual implementation plans that commenced in June 2019 and ongoing to June 2026.

Implementation Plan No. 1

The first implementation plan (June 2019–June 2022) was developed as part of a broader, co-invested national initiative under the Australian Government’s Rural R&D for Profit Round 4 (RRnDFP4), led by AgriFutures Australia. The NSW Environmental Trust pledged $250,000 cash to this national project, specifically supporting biocontrol research on four priority weeds: African boxthorn, African lovegrass, giant rat’s tail grass, and Hudson pear.

African boxthorn (Lycium ferocissimum)

https://research.csiro.au/african-boxthorn/achievements-rrnd4p-rnd-2/rural-rd-for-profit-round-4-project-2019-2023/

Research focused on host-specificity testing of candidate biocontrol agents for African boxthorn, including the assessment of up to two new agents. Promising candidates such as Cleta eckloni (a leaf-feeding beetle) and the rust fungus (Puccinia rapipes) identified through native range surveys were maintained in colonies for importation and testing.

African lovegrass (Eragrostis curvula)

African lovegrass was nominated as a candidate for biocontrol research for the first time globally. Surveys were conducted in southern Africa to identify natural enemies, with preliminary host range testing performed on promising agents such as specialist herbivores and pathogens found in the native range. This foundational work generated novel data essential for developing future biocontrol options for African lovegrass. This research was delivered by NSW DPIRD’s Weed Research Unit. For further details, contact team leader Andrew McConnachie, andrew.mcconnachie@dpird.nsw.gov.au.

Giant rat’s tail grass (Sporobolus natalensis)

The project prioritised endemic pathogens as candidate biocontrol agents for giant rat’s tail grass, with particular attention to the leaf smut fungus Ustilago sporoboli-indici. This project was led by NSW DPIRD and QDPI. For information see:

• https://www.business.qld.gov.au/industries/farms-fishing-forestry/agriculture/biosecurity/plants/invasive/restricted/giant-rats-tail-grass
• https://era.dpi.qld.gov.au/id/eprint/9300/

Hudson pear (Cylindropuntia pallida)

For Hudson pear, the cochineal insect Dactylopius tomentosus (lineage ‘californica var. parkeri’) was mass-reared and released as a biocontrol agent. The project evaluated the agent’s impact and dispersal at long-term monitoring sites, mapped the distribution of Hudson pear, and contributed to integrated management planning. Innovative technologies such as drones and artificial intelligence were used to monitor agent spread and weed suppression over large areas. This research was delivered by NSW DPIRD’s Weed Research Unit. For further details, contact team leader Andrew McConnachie, andrew.mcconnachie@dpird.nsw.gov.au.

Implementation Plan No. 2

Wandering trad (Tradescantia fluminensis)

https://research.csiro.au/wandering-trad/previous-research/2020-2023/

Implementation Plan 2 delivered one of the largest community-based mass-release programmes for weed biocontrol in NSW, distributing over 11,000 viable units of the leaf-smut fungus Kordyana brasiliensis to 248 participating groups and individuals for release at 425 sites. The fungus established at over 90% of release locations, with long-term monitoring showing successful establishment and spread at all experimental sites. Infection severity increased over time, resulting in significant reductions in wandering trad abundance and a corresponding increase in native plant species richness, demonstrating the positive ecological impact of coordinated biocontrol releases.

Small-leaf privet (Ligustrum sinense)

The privet lace bug, Leptoypha hospita, was imported and cultured in quarantine, with host-specificity testing conducted on small-leaf privet, broad-leaf privet (L. lucidum), and the native privet (L. australianum). While the insect fed and laid eggs on all three species, development was significantly higher on the target weed. However, some oviposition and feeding damage occurred on the native privet, raising concerns about potential spill-over effects. Further multi-generational and ecological host-range tests are planned before any decision is made regarding field release. This research was 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)

The root-feeding weevil Cyphocleonus trisulcatus was evaluated as a biocontrol agent for ox-eye daisy. Host-specificity trials in Switzerland and Australia showed that while the weevil can develop on ox-eye daisy and, to a lesser extent, on Shasta daisies and some related species, it does not develop on most other non-target species tested. Additional consultation with horticultural and commercial stakeholders is required before a release application can be submitted. Long-term monitoring of ox-eye daisy seedbanks and population dynamics at key sites continued, providing essential baseline data for future impact assessment. This research was delivered by NSW DPIRD’s Weed Research Unit. For further details, contact team leader Andrew McConnachie, andrew.mcconnachie@dpird.nsw.gov.au.

Implementation Plan No. 3

Sea spurge (Euphorbia paralias)

https://research.csiro.au/sea-spurge/previous-research-2017-2024/

Implementation Plan 3 delivered a large-scale community-based release of the fungal biocontrol agent Venturia paralias across Victoria and Tasmania. Over three years, the project team mass-produced and distributed 543 kits containing dried fungal material to 24 registered community participants, who released the agent at 231 coastal sites. Monitoring showed that the fungus established at 61% of sites where follow-up was possible, and at nine fixed monitoring sites, the agent became well established, with infection detected in up to 93% of plots in Tasmania and 71% in Victoria. Over time, a gradual decline in sea spurge health and cover was observed at these sites, indicating the agent’s potential to suppress the weed and support coastal ecosystem recovery.

Parrot’s feather (Myriophyllum aquaticum)

https://research.csiro.au/weed-biocontrol/parrots-feather-biological-control/

The stem-boring weevil Listronotus marginicollis was imported from Argentina and a healthy laboratory colony was established at CSIRO’s quarantine facility. Host-specificity testing was conducted on five native Australian Myriophyllum species. The weevil was able to complete its lifecycle on M. papillosum but at a much lower rate than on the target weed. Choice trials confirmed a strong preference for M. aquaticum over M. papillosum, with no lifecycle completion on the latter under choice conditions. These results indicate a promising level of host specificity, supporting further testing to assess risks to additional native species before any field release is considered.

Leafy elodea (Egeria densa)

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

 

Sagittaria (Sagittaria platyphylla)

The fruit- and flower-feeding weevil Listronotus appendiculatus was mass-reared and released by Agriculture Victoria and other stakeholders. More than 2,000 weevils were released at seven sites across Victoria and New South Wales, with additional cultures established for ongoing rearing. Monitoring detected persistence of weevil populations at three sites.

For more information, contact research leader Raelene Kwong: rae.kwong@agriculture.vic.gov.au

https://www.premier.vic.gov.au/weevils-called-combat-against-aquatic-weed-invasion

Implementation Plan No. 4

This project was first designed to deliver biocontrol solutions for three major weeds in New South Wales: leaf cactus (Pereskia aculeata), Brazilian pepper tree, and Japanese honeysuckle. The project aimed to identify and test suitable biocontrol agents for each weed, with the goal of progressing them towards safe release in Australia. For leaf cactus, the main focus was on the leaf-feeding beetle Phenrica guerini, which had already shown success as a biocontrol agent overseas.

As the project advanced, it became clear that research on Brazilian pepper tree and Japanese honeysuckle could not continue. This was due to scientific and logistical barriers. In April 2024, the project was formally revised to focus solely on leaf cactus.

The current focus of IP4 is on ensuring the safety and effectiveness of Phenrica guerini as a biocontrol agent for leaf cactus. This involves host-specificity testing, population genetic studies of the weed in Australia, and preparing a regulatory application for the beetle’s release. The research has shown that the beetle is highly specific to leaf cactus, and a draft application for its release has been completed.

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

Implementation Plan No. 5

African boxthorn (Lycium ferocissimum) 

https://research.csiro.au/african-boxthorn/current-research/our-research/

The main aim was to implement and evaluate the release of the rust fungus Puccinia rapipes as a biocontrol agent across New South Wales. The project delivered 14 workshops, distributed 275 release kits to 74 stakeholders, and established 17 permanent monitoring plots. After initial challenges with establishment due to extreme weather, infection was eventually detected on 34% of inoculated plants, and statistical analysis showed that infected plants produced about 62% fewer flowers and fruits after one year, indicating a promising reduction in reproductive output.

Cabomba (Cabomba caroliniana)

https://research.csiro.au/cabomba/our-research/

This project focused on establishing and releasing the weevil Hydrotimetes natans as a biocontrol agent. Robust weevil colonies were maintained at CSIRO and NSW DPIRD. Post-release monitoring confirmed weevil establishment and breeding at several sites, with Mooball Lagoon showing a clear reduction in cabomba biomass, while other sites had variable results likely influenced by environmental factors. Continued monitoring and further releases are planned to support long-term establishment and impact.