Pest Risk Assessment

7/31/2019 Pest Risk Assessment

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The standard provides details for the conduct of pest risk

analysis (PRA) to determine if pests are quarantine pests.

It describes the integrated processes to be used for riskassessment as well as the selection of risk management

options.


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Stage 1: Initiation.

Stage 2: Pest risk assessment.

Stage 3: Pest risk management.


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involves identifying the pest(s) and pathways thatare of quarantine concern and should beconsidered for risk analysis in relation to theidentified PRA area.

PRA could be initiated as a result of :a. Identification of a pathway that presents apotential pest hazard (ex; Importation) .

b. The identification of a pest that may requirephytosanitary measures*.

*(regulation or official procedure having the purpose to prevent theintroduction and/or spread of pests).


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Identification of PRA area

The PRA area should be defined as precisely as possible in orderto identify the area for which information is needed.

Information

Information gathering is an essential element of all stages ofPRA. It is important at the initiation stage in order to clarify

the identity of the pest(s), its/their present distribution and

association with host plants, commodities, etc.


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Previous PRA

A check should also be made as to whether pathways, pests orpolicies have already been subjected to the PRA process,

either nationally or internationally. If a PRA exists, its

validity should be checked as circumstances and information

may have changed. The possibility of using a PRA from a

similar pathway or pest, that may partly or entirely replace

the need for a new PRA, should also be investigated.


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The process for pest risk assessment can be broadly dividedinto three interrelated steps:

- Pest categorization

- Assessment of the probability of introduction and spread

-Assessment of potential economic consequences (including

environmental impacts).

*In most cases, these steps will be applied sequentially in a

PRA but it is not essential to follow a particular sequence.

Pest risk assessment needs to be only as complex as is

technically justified by the circumstances.


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Elements of categorization

- Identity of the pest ( species, virulence, host range)- Presence or absence in the PRA area (Should be absent)

-Regulatory status (If the pest is present but not widely distributed

in the PRA area, it should be under official control or expected

to be under official control in the near future)- Potential for establishment and spread in PRA area

- Potential for economic consequences (including environmental

consequences) in the PRA area.


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Probability of entry of a pest

The probability of entry of a pest depends on the pathways from theexporting country to the destination, and the frequency and quantity of

pests associated with them. The higher the number of pathways, the

greater the probability of the pest entering the PRA area.

Factors to consider are:

prevalence of the pest in the source area

occurrence of the pest in a life-stage that would be associated with

commodities, containers, or conveyances

volume and frequency of movement along the pathway

seasonal timing

pest management, cultural and commercial procedures applied at the

place of origin (application of plant protection products, handling,

culling, grading).


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Probability of survival during transport or storage

speed and conditions of transport and duration of the life

cycle of the pest in relation to time in transport and storage

susceptibility of the life-stages during transport or storage

prevalence of pest likely to be associated with a shipment commercial procedures (e.g. refrigeration) applied to

consignments in the country of origin, country of destination,

or in transport or storage.


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Probability of pest surviving existing pest management

procedures

Existing pest management procedures (including

phytosanitary procedures) applied to shipments against other

pests from origin to end-use, should be evaluated for

effectiveness against the pest in question.

The probability that the pest will go undetected during

inspection or survive other existing phytosanitary procedures

should be estimated.


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Availability of suitable hosts, alternate hosts and vectors

in the PRA area

whether hosts and alternate hosts are present and how

abundant or widely distributed they may be

whether hosts and alternate hosts occur within sufficient

geographic proximity to allow the pest to complete its life

cycle

whether there are other plant species, which could prove to

be suitable hosts in the absence of the usual host species

whether a vector, if needed for dispersal of the pest, is already

present in the PRA area or likely to be introduced

whether another vector species occurs in the PRA area.


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The conclusions from pest risk assessment are used to decide

whether risk management is required and the strength ofmeasures to be used. Since zero-risk is not a reasonable

option, the guiding principle for risk management should be

to manage risk to achieve the required degree of safety that

can be justified and is possible within the limits of availableoptions and resources.

Pest risk management (in the analytical sense) is the process

of identifying ways to react to a apparent risk, evaluating theefficacy of these actions, and identifying the most appropriate

options.


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Level of risk

Because some risk of introduction of a quarantine pest alwaysexists, countries shall agree to a policy of risk managementwhen formulating phytosanitary measures." In implementingthis principle, countries should decide what level of risk is

acceptable to them.

The acceptable level of risk may be expressed in a number ofways, such as:

reference to existing phytosanitary requirements indexed to estimated economic losses

expressed on a scale of risk tolerance

compared with the level of risk accepted by other countries.


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Technical information required

The decisions to be made in the pest risk management processwill be based on the information collected during the preceding

stages of PRA.

This information will be composed of: reasons for initiating the process

estimation of the probability of introduction to the PRA area

evaluation of potential economic consequences in the PRA

area.


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Acceptability of risk

Overall risk is determined by the examination of the outputs of

the assessments of the probability of introduction and the

economic impact.

If the risk is found to be unacceptable, then the first step in riskmanagement is to identify possible phytosanitary measures that

will reduce the risk to, or below an acceptable level.

Measures are not justified if the risk is already acceptable or

must be accepted because it is not manageable (as may be thecase with natural spread).

Countries may decide that a low level of monitoring or audit is

maintained to ensure that future changes in the pest risk are

identified.


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Pest riskassessment made by

France on

Nacoleia octasema


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Nacoleia octasema Meyrick, the banana scab moth,

(Insecta: Lepidoptera: Pyralidae) is primarily a pestof bananas and plantains (Musa spp.).

It is restricted to Australasia, south-east Asia andOceania.

Serious economic damage has been recorded

primarily in commercial plantations, e.g. inQueensland and Fiji, since the larvae feed on the skinof the banana fruit creating black scars that maygreatly reduce their market value but do not normally

affect yield.


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N. octasema is not reported or regulated as present in the

PRA area.

Due to the presence of suitable host plants in the PRA area

and the current geographical distribution of the pest in areas

with similar climates, the Panel agrees that Nacoleiaoctasema has the potential for establishment and spread in the

French overseas departments under consideration.

Susceptible banana cultivars are grown in the PRA area for

export, local markets and household consumption, and thus

the Panel agrees that N. octasema has the potential for

negative economic consequences in the PRA area.


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The Panel identified two main pathways: young banana plants andfruit. Only the latter was considered by the pest risk assessment.

Eggs cannot be transported since they are laid only on old plantsthat are not traded.

The larvae feed on the surface of the fruit and are therefore likelyto drop off during harvest and before shipment.

The pupa is formed in a silk cocoon at various sites on the plantand in litter near the base of the plant. Pupation can occur betweenthe banana fingers, so there is a possibility that these could enterbanana shipments.

Association with young plants is also very unlikely because eggsare only laid on old plants and larvae do not feed on young plants.Young plants for export will be grown in nurseries and thepresence of banana plant debris containing pupae in the soil is veryunlikely.


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Probability of survival during transport or storage

Banana fruit are usually transported and stored under cool

conditions (14C). The pupa and the adult moth are unlikelyto survive and reproduce in the hold of ships carryingbananas which are kept at these temperatures.

Any pupae in banana plant debris with soil and young plantsare likely to survive but the adults may well hatch in transit(CAB International 2007 states that 8-10 days are spent in thepupal stage).

On emergence, the moths are unlikely to find suitableconditions for survival, mating and oviposition and are short-lived, dying after 3-10 days.


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Probability of pest surviving existing pest management

procedures

This is not discussed by the pest risk assessment but the Panel

considers that current practices of washing and treating fruits

with disinfectants and/or fungicides before export are

expected to reduce the risks associated with the fruit pathwaystill further.

In the very unlikely event that pupae are present in banana

plant debris with soil and young plants, they are likely toescape detection.


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Probability of establishment and spread

The potential for establishment is very high. The tropical

and oceanic climate in the French overseas departments is

broadly similar to that in its current area of distribution and

Musa species, the principal host plants ofN. octasema, are

abundant and widespread.

The pest risk assessment does not provide a summary of the

potential of introduction. The Panel agreed that even though

the potential for establishment is very high, entry is very

unlikely and the conclusion for introduction must therefore

also be very unlikely.


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The Panel agrees with the pest risk assessment which states that entry isvery unlikely since the pupa is the only stage that could be transported.

Any pupae in the fruit bunches are likely to be washed offand plant debrisfrom the base of infested banana trees is very unlikely to occur with youngplants.

Even if the current ban on banana imports is lifted, the pest will have avery low probability of surviving the specific conditions of transport andtrade with countries where the pest occurs.

Imports are very unlikely since these countries are so far from the Frenchoverseas departments and home-produced fruit is readily available.

Passengers are also very unlikely to carry banana fruit that might containN. octasema the long distances from countries where the pest occurs intothe French overseas departments.


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Summary N. octasema poses a risk of high impact to Guadeloupe and

Martinique and low impact to French Guiana and Runion butthe probability of the impacts occurring is very low.

It is very difficult to come a firm conclusion in situations ofvery low probability and high impact but the Panel agreed that,on balance, an analysis of risk management options would beappropriate because it could be used to determine whether thevery unlikely risk of entry could be reduced to negligible withsimple measures.

The Panel therefore concludes that N. octasema does have thecharacteristics of a quarantine pest for Guadeloupe andMartinique and that the analysis of risk management options isappropriate for these two French overseas departments.

Pest Risk Assessment

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