Implementing Biocontrol of Cabomba caroliniana in NSW | Fritz Heystek
Tracks
Tuesday, August 5, 2025 |
1:50 PM - 2:10 PM |
Miconia Room |
Speaker
Mr Fritz Heystek
Research Officer
NSW DPIRD
Implementing Biocontrol of Cabomba caroliniana in NSW | Fritz Heystek
Abstract
Keywords:
Carolina fanwort, Carolina water shield
Cabomba caroliniana A. Gray (Cabombaceae, Cabomba) is a submerged, anchored, feathery-leaved herb with dense long stems. Native to South America, it was imported into Australia as an aquarium plant and is naturalised in still or slow-flowing freshwater systems in the NT, QLD, NSW and VIC. Control options are restricted by the weed’s habitat and environmental considerations. Additionally, after clearing, reinfestation often occurs from seed and turions. Cabomba impacts aquatic biodiversity, water quality, infrastructure and storage, and recreational and amenity values. As a result, Cabomba was nominated as a Weed of National Significance in Australia. A biological control (biocontrol) program was initiated in 2003, and exploration in Argentina resulted in the selection of Hydrotimetes natans Kolbe (Curculionidae) as potential agent. This aquatic weevil has a fairly short developmental period, is long-lived, and females are fecund. Eggs are laid on the apical tips and the first few nodes of Cabomba where hatched larvae bore into the foliage, then the shoots, causing plants to break up and desiccate. Field surveys and laboratory host-specificity studies demonstrated that H. natans was safe for release in Australia, with the weevil being field released in March 2022 in Queensland. A starter culture of H. natans was obtained by NSW DPIRD from CSIRO in 2023, and mass rearing was initiated. First releases in NSW were made in October 2023 at Mooball lagoon. Weevils were subsequently released at infestations at five more NSW sites (Clarie hall, Bucca, Mayers flat, Nana Glen & Glenugie) for evaluation. Initial establishment was observed at four sites, with reintroduction of the weevil being made at Bucca. Releases at Glenugie were made only recently. Establishment, spread and impact are being monitored through sampling along transects at these sites. The results from the post-release evaluation of H. natans will be presented in this talk.
Carolina fanwort, Carolina water shield
Cabomba caroliniana A. Gray (Cabombaceae, Cabomba) is a submerged, anchored, feathery-leaved herb with dense long stems. Native to South America, it was imported into Australia as an aquarium plant and is naturalised in still or slow-flowing freshwater systems in the NT, QLD, NSW and VIC. Control options are restricted by the weed’s habitat and environmental considerations. Additionally, after clearing, reinfestation often occurs from seed and turions. Cabomba impacts aquatic biodiversity, water quality, infrastructure and storage, and recreational and amenity values. As a result, Cabomba was nominated as a Weed of National Significance in Australia. A biological control (biocontrol) program was initiated in 2003, and exploration in Argentina resulted in the selection of Hydrotimetes natans Kolbe (Curculionidae) as potential agent. This aquatic weevil has a fairly short developmental period, is long-lived, and females are fecund. Eggs are laid on the apical tips and the first few nodes of Cabomba where hatched larvae bore into the foliage, then the shoots, causing plants to break up and desiccate. Field surveys and laboratory host-specificity studies demonstrated that H. natans was safe for release in Australia, with the weevil being field released in March 2022 in Queensland. A starter culture of H. natans was obtained by NSW DPIRD from CSIRO in 2023, and mass rearing was initiated. First releases in NSW were made in October 2023 at Mooball lagoon. Weevils were subsequently released at infestations at five more NSW sites (Clarie hall, Bucca, Mayers flat, Nana Glen & Glenugie) for evaluation. Initial establishment was observed at four sites, with reintroduction of the weevil being made at Bucca. Releases at Glenugie were made only recently. Establishment, spread and impact are being monitored through sampling along transects at these sites. The results from the post-release evaluation of H. natans will be presented in this talk.
Biography
Fritz Heystek is a research officer with the Weed Research Unit (Invasive Species Biosecurity, Biosecurity and Food Safety) of the NSW Department of Primary Industries and Regional Development. He conducted research to introduce biocontrol agents of several weeds at the ARC in South Africa and is curently focused on the implimentation of weed biocontrol in NSW, Australia.
