Hudson pear

The NSW Environmental Trust is one of the cash contributors to the national project ‘Underpinning agricultural productivity and biosecurity by weed biological control’ supported by the Australian Government programme Rural Research and Development for Profit (RRnD4P) (Round 4) administered by the Department of Agriculture, Water and the Environment. The three-year project (to June 2022) is led by AgriFutures Australia, focuses on 11 different weed targets and includes researchers from four agencies with capabilities and infrastructure to undertake weed biocontrol research in Australia (CSIRO, NSW Department of Primary Industries, Queensland Department of Agriculture and Fisheries and Victoria Department of Economic Development, Jobs, Transport & Resources).

Hudson pear (Cylindropuntia pallida) is one of the weed targets in which the NSW Environmental Trust is co-investing. Andrew McConnachie of NSW Department of Primary Industries is leading this sub-project.

The cochineal insect agent Dactylopius tomentosus (lineage ‘californica var. parkeri’) was first released for the biocontrol of Hudson pear in Australia in November 2017 in NSW and Queensland as part of a previous project supported by RRnD4P (Round 1). The current project is mass-rearing and releasing the agent on a large scale throughout the range of the weed and monitoring its impact at two sites in NSW. Multi spectral imagery captured by a drone is also being used to assess spread and impact of the agent over large spatial scales and across inaccessible terrain.

Planned activities

1. Mass-rear and release of Dactylopius tomentosus as a biocontrol agent for Hudson Pear.
2. Evaluate two long-term monitoring sites in NSW to assess biocontrol agent impact and dispersal.
3. Conduct mapping to establish the distribution of Hudson Pear in northern NSW.
4. Contribute to the integrated management plan for Hudson Pear in northern NSW.

Progress

2020/21

The cochineal Dactylopius tomentosus ‘californica var. parkeri lineage’ continued to be mass-reared at a dedicated facility in Lightning Ridge. A total of 33,900 Hudson pear cladodes infested by the insect were reared and released at 44 field sites in Western NSW. The insect was subsequently confirmed as established at all these release sites. Two workshops were held to provide information and training to community members on biological and chemical control of Hudson pear (Grawin 28 Aug 2020 – 16 participants; Lightning Ridge 29 August 2020 – 14 participants). A total of 20 community members were actively involved in making releases of the cochineal during the period.

 

Long term monitoring plots were assessed at Cumborah and Grawin in May, August and November 2020, and February and May 2021. Data collected included on-ground measures of cochineal dispersal and impact on Hudson pear as well as drone-acquired, high-resolution multispectral imagery. A GIS specialist at Greater Sydney LLS was subcontracted to; (1) create orthomosaics of the high-resolution multispectral data and (2) assess the NDVI values of the orthomosaics, to assess the impact of the Hudson pear cochineal. The company InFarm developed an Artificial Intelligence (AI) approach for detecting Hudson pear from aerial imagery taken by the DPI team. The AI was determined to be reliable and will be developed further to fast-track Hudson pear detection and impact assessment of the cochineal. Due to above average rainfall and COVID-related travel restrictions, the planned fixed-wing flights of 200 ha in the invaded range of Hudson pear to gather more imagery were postponed.

2019/20

The cochineal Dactylopius tomentosus (lineage ‘californica var. parkeri’) was first released in Australia in Nov 2017 and is being actively released as part of this project. The construction of the Hudson pear mass-rearing facility was completed in Lightning Ridge, NSW. Funding for this facility was kindly provided by the New South Wales Government. With the help of volunteers from Cumborah and weed staff from the Castlereagh Macquarie County Council, the facility was fully stocked with fresh, uninoculated Hudson pear material.

Since the mass-rearing facility in Lightning Ridge was commissioned, four landholders have directly participated in swapping fresh cladodes for inoculated cladodes. This number is set to escalate significantly now that the mass-rearing facility is reaching full capacity. Community members (29) have been trained in three workshops (held in Lightning Ridge, Cumborah and Grawin) in order to facilitate their involvement in the release programme.

A total of 840 rearing tubs for the cochineal were set up and field releases were made at 7 sites in the Lightning Ridge, Grawin and Cumborah areas. Impact and spread of the cochineal were monitored at two long-term field study sites at Grawin and Cumborah in February 2020. Establishment rate of the agent at the 7 sites where it was released in 2019/20 was 100%.