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Biological Control: Mass-rearing, Release
and Evaluation
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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
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Once approval for release of a new biological control
agent has been obtained from Biosecurity
Australia and the Department
of Environment and Heritage, the agent is mass-reared,
released throughout the distribution of the target weed,
and then evaluated to determine its impact on the weed
populations. Integrated
weed management or the release of additional agents
can be considered to enhance the overall impact on the
weed. CSIRO conducts research on all of these aspects,
often together with state or community collaborators
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Mass-rearing: The aims of mass-rearing are to
cost-effectively produce a large, continuous supply of
healthy agents (insects or pathogens) to release into
the field. Techniques generally have to be developed or
adjusted for each agent. Mass-rearing can be labour intensive
or relatively straight forwards. For example some insects
can easily be reared in large cages while others cannot
be reared at all. In the latter case adults are collected
from the native range, screened for parasites within a
containment facility and then released in the field. Fungal
pathogens, which are often used for biological control
of weeds, are either mass-cultured on artificial medium
(eg. facultative parasite) or on lived plants (eg. rust).
In any case careful attention is paid to ensure that genetic
diversity of insect populations or genetic integrity of
pathogen isolates is maintained and hygiene standards
are very high.
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Release: Small experimental field trials are often
made to determine an appropriate release strategy before
wide-scale distribution of the agent takes place. These
field trials are used to determine optimal release numbers
and timing, to gather information to assist with site
selection and to assess whether cages should be used or
sites be prepared (eg. bated for predators) prior to release.
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Redistribution: Once an appropriate release strategy
has been determined, the agent is redistributed to strategically
located sites in collaboration with other land management
organizations, landholders or community groups.
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Evaluation: Post-release evaluation of the agent
is critical to determine whether it has established, is
spreading and is having an impact. The evaluation stage
is helpful to improve release strategies, optimise impact
through integrated weed control and assist in the selection
of future additional agents.
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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
|
|
