This project advanced a range of biocontrol solutions that challenged traditional approaches and improved the management of two established weed species—Parthenium and Cat’s Claw Creeper (CCC)—in the Inland Burnett. It aimed to deliver long-term, sustainable management of these invasive weeds through the production and use of multiple biocontrol agents.

A biocontrol breeding facility was established at Monto, which produced CCC biocontrol agents including the Jewel Beetle and the Tingid Bug. CCC has widespread impacts on native ecosystems, particularly riparian zones, and interested landholders received bottles of 100 agents for release over three seasons.

The project achieved significant outcomes, including the distribution of over 15,000 Jewel Beetles across 58 release sites managed by 42 landholders, two Landcare groups, local council, and Queensland Parks and Wildlife Services (QPWS). Collectively, these participants managed more than 56,000 hectares across 21 river and creek systems. Notably, collaboration with QPWS allowed releases within sensitive areas such as Cania, Kroombit Tops, and Coominglah National Parks. Of all release sites, 47% had Jewel Beetles released for three seasons, 31% for two seasons, and 22% for one season. Monitoring showed 75% of sites had beetles established after 12 months, while persistence was confirmed at 65% of sites following the second release.

An extension of the project allowed 10 new landholders to participate and introduced the Tingid Bug, with over 3,000 agents released across 20 sites by landholders who collectively managed over 22,000 hectares of land, over 15 different waterways.

Parthenium, one of Australia’s most invasive and damaging weed species, has significant environmental and economic impacts including reduced livestock productivity, biodiversity loss, plant disease risks, and human health issues. Nationally, nine insects and two rust fungi are available as biocontrol agents, though eradication was not possible. Instead, a combination of agents were used to suppress growth by attacking different parts of the plant. At least three Parthenium biocontrol agents were already present in the Inland Burnett, and others were harvested for release from Central Queensland. New releases included the Zygogramma bicolorata beetle, Winter Rust, and Summer Rust across monitoring and landholder sites.

Parthenium agents were redistributed to 20 sites by landholders and local council who collectively managed over 15,000 hectares of land. While the Zygogramma bicolorata beetle and Winter Rust had limited success, a final large release of Summer Rust near Monto achieved strong establishment and visible suppression of Parthenium, laying the foundation for a future collection site to support ongoing regional control.

Focusing efforts on the upper Burnett River catchment provided long-term benefits, reducing weed reproductive material and enabling biocontrol agents to migrate downstream, amplifying the project’s impact across the catchment.