PEST RISK ANALYSIS (PRA) TRAINING Group Exercises Manual

PEST RISK ANALYSIS TRAINING - GROUP EXERCISES MANUAL GROUP EXERCISE NO. 3.2
GROUP EXERCISE NO. 3.2 – PROBABILITY OF ESTABLISHMENT AND SPREAD
Part 1 – Pest Risk Assessment, Probability of Establishment (1 hour)
In order to estimate the probability of establishment of a pest, reliable biological
information (life cycle, host range, epidemiology, survival etc. in the areas where the
pest presently occurs) should be obtained. The situation in the PRA area can then be
compared with that in the areas where the pest currently occurs, taking account also of
protected environments such as glass- or greenhouses, and expert judgement used to
assess the probability of establishment. Use the information provided to answer the
following questions:
1. Availability of suitable hosts, alternate hosts and vectors in the PRA
area
• What plant species are hosts for the pest? Are hosts and alternate hosts
present in the PRA area? How abundant or widely distributed are they? Do
they occur in discrete locations or are they distributed contiguously over a
wide area? In the case of non-parasitic plants that are pests, suitable habitats
may be considered instead of hosts.
• Are some hosts preferred or more susceptible than others? (mature vs. young
hosts, healthy vs. stressed hosts, etc)
• In the absence of the usual host species, does the pest have the ability to use
new hosts? (host specificity / adaptability)
• Do suitable hosts and alternate hosts occur near ports of entry or major
destinations? Do they occur within sufficient geographic proximity to allow
the pest to complete its life cycle?
• Does the pest have an active, directed host searching capability?
• Is a vector required for dispersal of the pest, and if so, is it already present in
the PRA area or likely to be introduced? Do other potential vectors occur in
the PRA area?
Availability of
hosts
Important
assumptions
2. Suitability of environment
• What is the pest’s current distribution? Is there evidence of successful
introductions in other world regions?
• Are suitable climatic conditions available in the PRA area? Are there any
known climatic factors limiting establishment of the pest? Where applicable,
consider the climatic factors required for initiation of different life cycle stages
(e.g. emergence, mating, egg laying, etc). Consider also the possibility of
establishment in a protected environment, e.g. in glasshouses.
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