Overview
Biological control kills or sterilises the target pest, thereby reducing its abundance within the designated site or area.
- Examples of biological control agents include parasitoids, predators, or pathogenic fungi or viruses. This measure also includes the release of sterile insects (Sterile Insect Technique (SIT)).
- Evaluating the efficacy of biological control agents (including SIT) involves assessing how effective they are at suppressing pest populations, and thereby infestation rates.
- Biological control is widely used to manage pest populations and can be considered when conducting a pest risk assessment. Augmentative biological control and SIT can be used as a phytosanitary measure, but would generally be applied as a dependent measure supporting another phytosanitary measure like an Area of Low Pest Prevalence.
- Assurance can be achieved through maintenance and audit of release and evaluation records. In some cases, physical audits can also be conducted.
Evidence to support efficacy
Evidence is required to demonstrate that the biological control agent (or SIT) consistently and reliably reduces pest levels to the required level. This generally requires an assessment of both the direct effects of biological control on the pest (e.g. parasitism or predation rates through time) and how that affects population suppression at times when the commodity is vulnerable. Data from several seasons and across any environmental gradients in the control area may be needed because pest and agent abundance can change in response to environmental factors.
Applying the measure
How it is used
Classical biological control is where a foreign biological control agent is released and becomes established without further intervention. The agent generally becomes established across larger areas. Their role in reducing pest populations, which can be dramatic, can be considered during risk assessment but not as a phytosanitary measure.
Augmentative biological control is where ongoing releases are needed to maintain populations of the biological control agent. These are usually applied seasonally or in response to pest outbreaks at the site-level. Augmentative releases of predators or parasitoids are particularly common in protected cropping. However, care is needed to ensure that other measures, such as pesticides, do not limit the efficacy of biological control. Routine commercial use can be considered when assessing pest risks, or it can be proposed as a phytosanitary measure.
Sterile Insect Technique can provide effective control of pest insect populations. Sterilised male insects are released to mate with wild females, resulting in no fertile offspring. SIT is generally applied for area-wide management. It can be considered during risk-assessment or proposed as a phytosanitary measure.
Use with other measures
Biological control is usually only used as a supporting measure in an Area or Site of Low Pest Prevalence. This is because the pest population needs to be above zero to support a viable population of the biological control agent.
Augmentative biological control and SIT are generally combined with other measures that also minimise exposure to the pest, such as other pest management measures, protected facilities or buffer zones.
Similar measures
Biological control (including SIT) may be used as a component of Integrated Pest and Disease Management (IPDM). Sterile Insect Technique is sometimes used as a corrective action to help manage outbreaks within Pest Free Areas.
Assurance of correct implementation
Records of the location and dates of the release of biological control agents may be required. For agents that are already established in the production region, records of the presence of the biological control agent may be sufficient. These records may be audited by authorised personnel, with oversight by the NPPO or relevant authority of the exporting jurisdiction.