Biological Control: Host Specificity Testing

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Steps in a Weed Biological Control Program | Choosing Target Weed | Native-range Surveying | Choosing Best Potential Agent | Host-specificity Testing | Mass-rearing, Release and Evaluation | Non-target Impacts

• Host specificity testing is the key tool for assessing whether a candidate agent for biological control is safe to release into a new environment.

  Louise Morin receiving the first shipment of bridal creeper rust fungus in 1998 to undertake host-specificity testing in the CSIRO Black Mountain Containment Facility.

• Host specificity testing is a regulatory requirement and a prerequisite to obtaining permission to release new biological control agents into Australia. The potential agent is thoroughly tested on a number of plants species (the test list), which is approved by Biosecurity Australia. This is often done in two stages:

  • In the country of origin the candidate agent is tested on a few plant species closely related to the target weed. If it is found to be host-specific in these preliminary tests, an application is made to Biosecurity Australia and the Department of Environment and Heritage to obtain approval to import the agent into an Australian containment facility for more extensive testing.

  • In the Australian containment facility, all non-target plants of the approved test list are exposed to the agent to determine if it can survive or reproduce on them.

• If the tests show that the agent is host-specific, an application for release in Australia is then made to Biosecurity Australia and the Department of Environment and Heritage. The application is assessed by 21 agricultural, conservation and scientific organisations, with final approval for release being granted by both Biosecurity Australia and the Department of Environment and Heritage. All 21 organisations must unanimously agree the agent is safe for release.

• CSIRO has an active research program to improve the way host-specificity testing is carried out in order to ensure that procedures are more cost-effective and that results are fully reliable. Fundamental research is also conducted to help improve our basic knowledge of plant-insect and plant-pathogen interactions, especially with regards to the behavioural and physiological basis of host choice/range and utilisation/colonisation.

• For more details see: Briese, D.T. (2003). The centrifugal phylogenetic method used to select plants for host-specificity testing of weed biological control agents: Can and should it be modernised?. In: Improving the selection, testing and evaluation of weed biological control agents, (eds H. Spafford Jacob & D.T. Briese), pp. 23-33. CRC for Australian Weed Management, Technical Series 7.

  Paul Yeoh conducting host-specificity tests on Emex agents.

Biological Control Home | Key Resources

Steps in a Weed Biological Control Program | Choosing Target Weed | Native-range Surveying | Choosing Best Potential Agent | Host-specificity Testing | Mass-rearing, Release and Evaluation | Non-target Impacts