The probability of entry describes the probability that a quarantine pest will enter Australia as a result of trade in a given commodity, be distributed in a viable state in the PRA area and subsequently be transferred to a host. It is based on pathway scenarios depicting necessary steps in the sourcing of the commodity for export, its processing, transport and storage, its utilisation in Australia and the generation and disposal of waste. In particular, the ability of the pest to survive is considered for each of these various stages.
The probability of entry estimates for the quarantine pests for a commodity are based on the use of the existing commercial production, packaging and shipping practices of the exporting country. Details of the existing commercial production practices for the commodity are set out in Section 3. These practices are taken into consideration by Biosecurity Australia when estimating the probability of entry.
For the purpose of considering the probability of entry, Biosecurity Australia divides this step of this stage of the PRA into two components:
Probability of importation: the probability that a pest will arrive in Australia when a given commodity is imported
Probability of distribution: the probability that the pest will be distributed, as a result of the processing, sale or disposal of the commodity, in the PRA area and subsequently transfer to a susceptible part of a host.
Factors considered in the probability of importation include:
distribution and incidence of the pest in the source area
occurrence of the pest in a life-stage that would be associated with the commodity
volume and frequency of movement of the commodity along each pathway
seasonal timing of imports
pest management, cultural and commercial procedures applied at the place of origin
speed of transport and conditions of storage compared with the duration of the lifecycle of the pest
incidence of the pest likely to be associated with a consignment
commercial procedures (e.g. refrigeration) applied to consignments during transport and storage in the country of origin, and during transport to Australia.
Factors considered in the probability of distribution include:
commercial procedures (e.g. refrigeration) applied to consignments during distribution in Australia
dispersal mechanisms of the pest, including vectors, to allow movement from the pathway to a host
whether the imported commodity is to be sent to a few or many destination points in the PRA area
proximity of entry, transit and destination points to hosts
time of year at which import takes place
intended use of the commodity (e.g. for planting, processing or consumption)
risks from by-products and waste.
Probability of establishment
Establishment is defined as the ‘perpetuation for the foreseeable future, of a pest within an area after entry’ (FAO 2004). In order to estimate the probability of establishment of a pest, reliable biological information (lifecycle, host range, epidemiology, survival, etc.) is obtained from the areas where the pest currently occurs. The situation in the PRA area can then be compared with that in the areas where it currently occurs and expert judgement used to assess the probability of establishment.
Factors considered in the probability of establishment in the PRA area include:
availability of hosts, alternative hosts and vectors
Spread is defined as ‘the expansion of the geographical distribution of a pest within an area’ (FAO 2004). The probability of spread considers the factors relevant to the movement of the pest, after establishment on a host plant or plants, to other susceptible host plants of the same or different species in other areas. In order to estimate the probability of spread of the pest, reliable biological information is obtained from areas where the pest currently occurs. The situation in the PRA area is then carefully compared with that in the areas where the pest currently occurs and expert judgement used to assess the probability of spread.
Factors considered in the probability of spread include:
suitability of the natural and/or managed environment for natural spread of the pest
presence of natural barriers
the potential for movement with commodities, conveyances or by vectors
intended use of the commodity
potential vectors of the pest in the PRA area
potential natural enemies of the pest in the PRA area.
Assigning qualitative likelihoods for the probability of entry, establishment and spread
In its qualitative PRAs, Biosecurity Australia uses the term ‘likelihood’ for the descriptors it uses for its estimates of probability of entry, establishment and spread. Qualitative likelihoods are assigned to each step of entry, establishment and spread. Six descriptors are used: high; moderate; low; very low; extremely low; and negligible (Table 2.1). Descriptive definitions for these descriptors and their indicative probability ranges are given in Table 2.1. The indicative probability ranges are only provided to illustrate the boundaries of the descriptors. These indicative probability ranges are not used beyond this purpose in qualitative PRAs. The standardised likelihood descriptors and the associated indicative probability ranges provide guidance to the risk analyst and promote consistency between different risk analyses.
Table 2.1: Nomenclature for qualitative likelihoods
The likelihood of entry is determined by combining the likelihood that the pest will be imported into the PRA area and the likelihood that the pest will be distributed within the PRA area, using a matrix of rules (Table 2.2). This matrix is then used to combine the likelihood of entry and the likelihood of establishment, and the likelihood of entry and establishment is then combined with the likelihood of spread to determine the overall likelihood of entry, establishment and spread.
For example, if the probability of importation is assigned a likelihood of ‘low’ and the probability of distribution is assigned a likelihood of ‘moderate’, then they are combined to give a likelihood of ‘low’ for the probability of entry. The likelihood for the probability of entry is then combined with the likelihood assigned to the probability of establishment (e.g. ‘high’) to give a likelihood for the probability of entry and establishment of ‘low’. The likelihood for the probability of entry and establishment is then combined with the likelihood assigned to the probability of spread (e.g. ‘very low’) to give the overall likelihood for the probability of entry, establishment and spread of ‘very low’.
Table 2.2: Matrix of rules for combining qualitative likelihoods
Time and volume of trade
One factor affecting the likelihood of entry is the volume and duration of trade. If all other conditions remain the same, the overall likelihood of entry will increase as time passes and the overall volume of trade increases.
Biosecurity Australia normally considers the likelihood of entry on the basis of the estimated volume of one year’s trade. This is a convenient value for the analysis that is relatively easy to estimate and allows for expert consideration of seasonal variations in pest presence, incidence and behaviour to be taken into account. The consideration of the likelihood of entry, establishment and spread and subsequent consequences takes into account events that might happen over a number of years even though only one year’s volume of trade is being considered. This difference reflects biological and ecological facts, for example where a pest or disease may establish in the year of import but spread may take many years.
The use of a one year volume of trade has been taken into account when setting up the matrix that is used to estimate the risk and therefore any policy based on this analysis does not simply apply to one year of trade. Policy decisions that are based on Biosecurity Australia’s method that uses the estimated volume of one year’s trade are consistent with Australia’s policy on appropriate level of protection and meet the Australian Government’s requirement for ongoing quarantine protection. Of course, if there are substantial changes in the volume and nature of the trade in specific commodities then Biosecurity Australia has an obligation to review the risk analysis and, if necessary, provide updated policy advice.
In assessing the volume of trade in this PRA, Biosecurity Australia assumed that a small volume of specialised trade will occur (refer to Chapter 3).
The objective of the consequence assessment is to provide a structured and transparent analysis of the likely consequences if the pests or disease agents were to enter, establish and spread in Australia. The assessment considers direct and indirect pest effects and their economic and environmental consequences. The requirements for assessing potential consequences are given in Article 5.3 of the SPS Agreement (WTO 1995), ISPM 5 (FAO 2008) and ISPM 11 (FAO 2004).
Direct pest effects are considered in the context of the effects on:
plant life or health
other aspects of the environment.
Indirect pest effects are considered in the context of the effects on:
eradication, control, etc.
For each of these six criteria, the consequences were estimated over four geographic levels, defined as:
Local: an aggregate of households or enterprises (a rural community, a town or a local government area).
District: a geographically or geopolitically associated collection of aggregates (generally a recognised section of a state or territory, such as ‘Far North Queensland’).
Regional: a geographically or geopolitically associated collection of districts in a geographic area (generally a state or territory, although there may be exceptions with larger states such as Western Australia).
National: Australia wide (Australian mainland states and territories and Tasmania).
For each criterion, the magnitude of the potential consequence at each of these levels was described using four categories, defined as:
Indiscernible: Pest impact unlikely to be noticeable.
Minor significance: Expected to lead to a minor increase in mortality/morbidity of hosts or a minor decrease in production but not expected to threaten the economic viability of production. Expected to decrease the value of non-commercial criteria but not threaten the criterion’s intrinsic value. Effects would generally be reversible.
Significant: Expected to threaten the economic viability of production through a moderate increase in mortality/morbidity of hosts, or a moderate decrease in production. Expected to significantly diminish or threaten the intrinsic value of non-commercial criteria. Effects may not be reversible.
Major significance: Expected to threaten the economic viability through a large increase in mortality/morbidity of hosts, or a large decrease in production. Expected to severely or irreversibly damage the intrinsic ‘value’ of non-commercial criteria.
Values were translated into a qualitative impact score (A–G)2 using Table 2.3.
Table 2.3: Decision rules for determining the consequence impact score
The overall consequence for each pest is achieved by combining the qualitative impact scores (A–G) for each direct and indirect consequence using a series of decision rules (Table 2.4). These rules are mutually exclusive, and are assessed in numerical order until one applies.
Table 2.4: Decision rules for determining the overall consequence rating for each pest
The impact scores for consequences of direct and indirect criteria
Overall consequence rating
Any criterion has an impact of ‘G’; or
more than one criterion has an impact of ‘F’; or
a single criterion has an impact of ‘F’ and each remaining criterion an ‘E’.
A single criterion has an impact of ‘F’; or
all criteria have an impact of ‘E’.
One or more criteria have an impact of ‘E’; or
all criteria have an impact of ‘D’.
One or more criteria have an impact of ‘D’; or
all criteria have an impact of ‘C’.
One or more criteria have an impact of ‘C’; or
all criteria have an impact of ‘B’.
One or more but not all criteria have an impact of ‘B’, and
all remaining criteria have an impact of ‘A’.
2.2.4 Estimation of the unrestricted risk
Once the above assessments are completed, the unrestricted risk can be determined for each pest or groups of pests. This is determined by using a risk estimation matrix (Table 2.5) to combine the estimates of the probability of entry, establishment and spread and the overall consequences of pest establishment and spread. Therefore, risk is the product of likelihood and consequence.
When interpreting the risk estimation matrix, note the descriptors for each axis are similar (e.g. low, moderate, high) but the vertical axis refers to likelihood and the horizontal axis refers to consequences. Accordingly, a ‘low’ likelihood combined with ‘high’ consequences, is not the same as a ‘high’ likelihood combined with ‘low’ consequences – the matrix is not symmetrical. For example, the former combination would give an unrestricted risk rating of ‘moderate’, whereas, the latter would be rated as a ‘low’ unrestricted risk.
Likelihood of pest entry, establishment and spread
Very low risk
Very low risk
Very low risk
Very low risk
Very low risk
Very low risk
Consequences of pest entry, establishment and spread
2.2.5 Australia’s appropriate level of protection (ALOP)
The SPS Agreement defines the concept of an ‘appropriate level of sanitary or phytosanitary protection (ALOP)’ as the level of protection deemed appropriate by the WTO Member establishing a sanitary or phytosanitary measure to protect human, animal or plant life or health within its territory.
Like many other countries, Australia expresses its ALOP in qualitative terms. Australia’s ALOP, which reflects community expectations through government policy, is currently expressed as providing a high level of sanitary or phytosanitary protection aimed at reducing risk to a very low level, but not to zero. The band of cells in Table 2.5 marked ‘very low risk’ represents Australia’s ALOP.
2.3 Stage 3: Pest risk management
Pest risk management describes the process of identifying and implementing phytosanitary measures to manage risks to achieve Australia's ALOP, while ensuring that any negative effects on trade are minimised.
The conclusions from pest risk assessment are used to decide whether risk management is required and if so, the appropriate measures to be used. Where the unrestricted risk estimate exceeds Australia’s ALOP, risk management measures are required to reduce this risk to a very low level. The guiding principle for risk management is to manage risk to achieve Australia’s ALOP. The effectiveness of any proposed phytosanitary measure (or combination of measures) is evaluated, using the same approach as used to evaluate the unrestricted risk, to ensure it reduces the restricted risk for the relevant pest or pests to meet Australia’s ALOP.
ISPM 11 (FAO 2004) provides details on the identification and selection of appropriate risk management options and notes that the choice of measures should be based on their effectiveness in reducing the probability of entry of the pest.
Examples given of measures commonly applied to traded commodities include:
options for consignments – e.g., inspection or testing for freedom from pests, prohibition of parts of the host, a pre-entry or post-entry quarantine system, specified conditions on preparation of the consignment, specified treatment of the consignment, restrictions on end-use, distribution and periods of entry of the commodity
options preventing or reducing infestation in the crop – e.g., treatment of the crop, restriction on the composition of a consignment so it is composed of plants belonging to resistant or less susceptible species, harvesting of plants at a certain age or specified time of the year, production in a certification scheme
options ensuring that the area, place or site of production or crop is free from the pest – e.g., pest-free area, pest-free place of production or pest-free production site
options for other types of pathways – e.g., consider natural spread, measures for human travellers and their baggage, cleaning or disinfestation of contaminated machinery
options within the importing country – e.g., surveillance and eradication programs
prohibition of commodities – if no satisfactory measure can be found.
Risk management measures are identified for each quarantine pest where the risk exceeds Australia’s ALOP. These are presented in the ‘Pest Risk Management’ section of this report.
Japan’s commercial production practices for Citrus unshiu
Assumptions used to estimate unrestricted risk
Biosecurity Australia took into consideration the following information on the existing commercial production practices in Japan when estimating the unrestricted risks of pests likely to be associated with fresh unshu mandarin fruit produced in the production area near Fujieda City in the Shizuoka Prefecture. The information was verified when officers from Biosecurity Australia travelled to Japan in June 2006 and July 2007 to observe the existing commercial production practices and processing procedures for fresh unshu mandarin fruit in the production area and a nearby registered packing house for export unshu mandarin. These visits clarified Biosecurity Australia’s understanding of the cultivation and harvesting methods, pest control and packing and transport protocols recommended to produce and export fresh unshu mandarin fruit to Australia. These protocols conform to commercial production practices (e.g. orchard management, hygiene and quality control).
Production area and designated export areas
The production area is near Fujieda City containing the four designated export areas (Figure 3.2) from which fresh unshu mandarin fruit would be exported to Australia. It is located in the Shizuoka Prefecture in the central part of Honshu Island that is part of the most northern citrus producing region in Japan (Figure 3.1). The production area is situated in the foothills of Mount Fuji, in the north-western inland region of Shizuoka Prefecture. These foothills reach 200–300 m in height.
Endemic Cryptomeriajaponica forest and some deciduous mixed forest cover the ridgeline of hills surrounding this production area (Figure 3.3). These forested ridgelines present a natural buffer separating this unshu production area from other citrus growing areas within the Fujieda region. Horticultural production in the production area consists of unshu mandarin, bamboo and tea plantations (Figure 3.4). All four designated unshu mandarin export areas are situated on the lower slopes of steep, terraced hillsides (Figures 3.3 and 3.4). The export areas are uninhabited, but there is some habitation along the road within the production area. The closest population centre is Fujieda City, which lies to the east of the production area.
Japan indicated that the four designated export areas have a combined size of 25 hectares, consist of 150 orchards and 25 518 unshu mandarin trees. The majority of orchards within the four designated export areas participate in the export trade. These orchards are well established, consisting of mature, fruiting unshu mandarin trees. MAFF provided information that the orchards in the designated export areas commenced fruit exports from the existing trees to the USA more than 40 years ago. Mechanisation of orchards is minimal due to the steep terrain.
Figure 3.1: Major citrus growing areas in Japan
Figure 3.2: The unshu mandarin production area and the designated export areas (Areas 1–4) near Fujieda City, Shizuoka Prefecture
The outline that defines the production area is provided as a series of coordinates in ArcGIS. These coordinates are set out in Table 3.1.
Table 3.1: Coordinates for the production area
N 3° 57'28"
Since the draft report, MAFF provided the coordinates that define the four designated export areas. These are listed in Table 3.2.
Table 3.2: Coordinates for the four designated export areas
N 34º56’56” to N 34º56’02”
E 138º13’32” to E 138º14’43”
N 34º56’02” to N 34º55’41”
E 138º12’57” to E 138º13’36”
N 34º55’32” to N 34º55’13”
E 138º13’02” to E 138º13’20”
N 34º54’58” to N 34º54’35”
E 138º13’49” to E 138º14’20”
Figure 3.3: Orchard within the designated export areas
Figure 3.5: Mature unshu mandarin tree grafted on Poncirus trifoliata
Figure 3.7: Fruit processing plant
Figure 3.4: Orchard within the designated export areas surrounded by tea, bamboo and mixed tree vegetation
In 2007 Japan provided climatic information for the production area from the closest meteorological station at Shizuoka City (Table 3.3). Shizuoka City is situated in the coastal lowlands of Shizuoka Prefecture about 50 km to the north-east of the production area. The Prefecture, except for the northern mountainous region, has a mild oceanic climate throughout the year. Seasons in all parts of the Prefecture are distinct; the spring is mild, followed by a rainy (>1000 mm average rainfall) and then hot and sunny summer, cool autumn and cool and dry winter. The average annual temperature within the Prefecture is 16ºC and the average annual rainfall is 2360 mm (Anon 2008).
Table 3.3: Rainfall and temperature figures for Shizuoka City
Averages for the years 2002 to 2006
Maximum Temperature (ºC)
During summer and early autumn (generally July to October), Japan experiences a number of strong weather events known as typhoons. An average of three typhoons per year approach the coastline of the Tokai region, which includes the Aichi, Gifu, Mie and Shizuoka Prefectures (Table 3.4). The impact of typhoons is felt on the flat coastal lowlands, including the coastline of Shizuoka Prefecture. Biosecurity Australia officers, during their site visit in 2007, were advised that the mountainous inland terrain that surrounds the production area provides shelter from typhoons.
Table 3.4: Number of typhoons that approached the Tokai region