The objectives of a PRA are, for a specified area, to identify pests and/or pathways of quarantine concern and evaluate their phytosanitary risk, to identify endangered areas, and, if appropriate, to identify risk management options. In accordance with ISPM No. 11, a PRA has three distinct stages:
Stage I, initiation, involves identifying the pest(s) and pathway(s) that are of quarantine concern and should be considered for risk analysis in relation to the identified PRA area. In this standard the pests are identified as scale insects associated with the importation pathway for fresh fruit and vegetables for human consumption.
Stage II, pest risk assessment, begins with the categorization of individual pests to determine whether the criteria for a quarantine pest are satisfied. Risk assessment continues with an evaluation of the probability of pest entry, establishment, and spread, and of their potential economic consequences (including environmental consequences).
2.1 Probability of entry
In determining the likelihood that a given species will enter, in a viable state, the PRA area with the importation of fresh fruit and vegetable for human consumption, consider:
For scale insects it is important to consider:
2.2 Probability of establishment
In determining the likelihood that a given species will establish in the PRA area following entry consider:
For scale species it is important to consider:
2.3 Probability of spread after establishment
In determining the likelihood that a given species of scale insect will spread in the PRA area following entry and establishment consider:
For scale insects it is important to consider:
2.4 Assessment of potential economic consequences
2.4.1 Direct pest effects
The direct effects of scale insects on host plant life or health should be assessed. Considerations may include: potential host plants; the pest's rate of spread and reproduction; degree of damage; and changes in yields.
Scale insects can cause direct harm to a wide range of host plants, affecting plant health as well as fruit quality. Scale insects feed on sap by means of long feeding stylets. Once feeding commences, they usually remain attached to the host plant permanently.
2.4.2 Indirect pest effects
Effect on trade
Assessment may include effects on the domestic market and/or international market access. Additional effects may include changes in consumer demand for affected commodities.
Indirect pest effects are those effects that are not host-specific. Certain species of scale insects may secrete honeydew, so sooty mould growth or attendances by ants may be issues of concern.
Impacts of eradication and control
The impact of eradication and control may include the cost of control measures and the effects on production systems such as those on organic production systems. Assessment may also include changes to production costs.
Non-commercial and environmental
Assessment of the effects on the environment may include changes in plant community structure, and impacts on endangered flora and may include effects on non-market values (e.g. amenity or ecosystem stability, biodiversity).
Stage III, pest risk management, is the evaluation, selection and application of measures to mitigate the risk associated with the entry, establishment and spread of quarantine pests.
If the risk associated with scale insects is determined to be above a country's Appropriate Level of Protection (ALOP) for fresh fruit and vegetables for human consumption, phytosanitary measures may be applied. Assessment should be given to the efficacy, feasibility and impact of these measures in order to select the most appropriate measures that are least trade restrictive and have minimal impact on the environment.
The following phytosanitary measures are proposed to mitigate this risk, but this does not exclude any equivalent measures.
The following measures may be applied singly or as part of a systems approach as set out in ISPM No. 14, The use of integrated measures in a systems approach for pest risk management.
3.1 Sourcing commodities from designated areas
3.1.1 Sourcing the commodity from a pest free area
The requirements for establishing pest free areas are set out in ISPM No. 4, Requirements for the establishment of pest free areas.
3.1.2 Sourcing the commodity from a pest free place of production or pest free production site
The requirements for establishing pest free places of production or pest free production sites are set out in ISPM No. 10, FAO, Requirements for the establishment of pest free places of production and pest free production sites, 1999.
3.1.3 Sourcing the commodity from an area of low pest prevalence
The requirements for establishing areas of low pest prevalence are set out in ISPM No. 22, Requirements for the establishment of areas of low pest prevalence.
3.2 In-field management for scale insects
Production areas may be registered with the NPPO of the exporting country to produce commercial export-grade commodity and manage in-field the scale insects identified as being of quarantine concern. In-field management measures may include control of these pests during production.
3.3 Post-harvest management of scale insects
Packing houses may be registered with the NPPO of the exporting country to undertake post-harvest specific phytosanitary procedures that may be required to manage the pest risk of specific life stages of specific pests.
3.4 Pre-export phytosanitary inspection and possible remedial action
Consignments may be inspected pre-export by the exporting country's NPPO or delegated authority (under a bilaterally agreed arrangement) or by the importing NPPO under a pre-clearance arrangement.
Inspection of the commodity is to be completed after commercial grading, sanitation, and pre-export disinfestation treatment (if applicable). Commodities for export should comply with all risk management measures identified by the PRA. The detection of scale insects that are quarantine pests for the importing country during pre-export inspection may result in remedial action including withdrawal of the consignment from export.
3.5 On arrival phytosanitary inspection and possible remedial action
On arrival each consignment that had not been inspected prior to export (either inaccordance with a bilateral arrangement or through a pre-clearance programme) should preferably be inspected at the first port of entry. Inspection of the commodity should be conducted in accordance with ISPM No. 23, Guidelines for inspection, 2005.
No detection of pests by inspection of the consignment provides a measure of confidence that the required measures have been effectively implemented in the exporting country and that the consignment is free of pests of quarantine concern.
Consignments accompanied with appropriate documentation from either a pre-export inspection or pre-clearance programme should only require document verification and standard import procedures (in relation to scale pests).
Efficacious disinfestation treatments may be considered as effective measures, for example:
3.6.1 Methyl-bromide fumigation
Following commercial grading and sanitation procedures, consignments of the commodity may be fumigated with methyl-bromide. This may occur either pre-export or on arrival. The fumigation methods should be determined through pest risk analysis including identified risks and relevant established treatment standards or conditions established under a bilateral arrangement.
Guidance on the use of irradiation as a phytosanitary measure are set out in ISPM No. 18, Guidelines for the use of irradiation as a phytosanitary measure, 2003.
3.6.3 Alternative treatments
Alternative treatments with proven efficacy as measures against scale insects may be considered.