19th Meeting of the Panel on PRA Development

Paris, 2010-05-14/17


The 19th Meeting of the Panel on PRA Development was held in Paris. As for the previous meeting, the Panel followed a different procedure than usual, as the work was focused on reviewing the results of the EU project on PRA, 'PRATIQUE' in which EPPO is involved. The meeting therefore aimed at providing guidance for further work, but no change would be implemented in the EPPO decision-support scheme (EPPO DSS, PM5/3(4)) before the end of the PRATIQUE project in March 2011.


Visualization tool »


Horizontal issues

Timescale in PRA
One recommendation made by PRATIQUE is that the questions in the EPPO PRA decision-support scheme are answered for a five year future time period. The Panel on Phytosanitary Measures was consulted and considered that agreeing a fixed period is not possible and that any timescale should be fixed on a case by case basis. The Panel on PRA development discussed the relevance of timescale for the different sections of the PRA scheme and how it was feasible to answer each question within a timeframe. It was concluded that in the entry section an opinion on the future trends could be given when concluding this section. For the establishment section no further inclusion of a future timescale is necessary in addition to what is currently done when assessing climate. For spread and impact a timescale should be included and this should be elaborated further.


Can the assessor answer no judgment?
The Panel agreed that the assessor should try to answer all questions. Only in specific cases (no information, or contradictory information), can ‘no judgment’ be answered. A justification should be provided to explain why ‘no judgment’ was selected.


How detailed should the entry section be?
The Panel agreed that the entry section of EPPO PRAs is very detailed compared to other PRAs worldwide. It was concluded that the opinion of risk managers should be asked as to whether such a level of detail was needed.


Do the questions on eradication and containment belong in the risk assessment section or the risk management section of the EPPO Pest Risk Analysis DSS? 
The Panel agreed that it is important to evaluate how a pest can establish and spread without any specific measures directed to eradicate or contain it. Then any potential measures which can be directed at preventing entry or preventing establishment and further spread should be identified and their effectiveness evaluated in the management part.



Results of several Work Packages (WP) within PRATIQUE

WP 2 – Enhancing techniques for economic, environmental and social impacts
One of the tasks of WP2 is to determine the key indicators required for impact assessment and to develop a quantitative scoring system for these indicators that can be related to the five levels of scoring required for each question in the EPPO PRA scheme (minimal, minor, moderate, major or massive). During the previous Panel meeting, it was recommended that in addition to a quantitative impact assessment module, a qualitative economic impact assessment module should be provided. Both a quantitative (developed and tested for PSTVd) and a qualitative model were presented. 

Regarding the quantitative model the Panel agreed that when sufficient data is available and a detailed analysis is needed the model would help with economic assessment but felt that it is still complex for non-economists, because of the economic concepts included. The Panel felt that a qualitative approach would probably be used in practice in most cases. The Panel recommended that guidance should be prepared on how to decide whether to run the quantitative impact assessment module.
A qualitative model was tested and the Panel recommended that the text of the revised questions should be revisited.


WP 3 – Enhancing techniques for standardising and summarising pest risk assessments & dealing with uncertainty
Visualization tool
A prototype of a visualization tool was presented for the entry section. This tool allows the assessor to see on a chart the value given for individual answers in a section. The objective is to help to give a final score for each section (or in the entry section as showed in the graph above for each pathway). The Panel recommended that it should be developed further. This tool will be provided within CAPRA at the end of the Entry section when the assessors need to draft the conclusion. 


Rating guidance
Rating guidance to provide consistency in the different assessments performed with the EPPO DSS, have been developed further in particular for the establishment part of the scheme. The Panel welcomed in particular the inclusion of more examples in the rating guidance.


Bayesian Belief Network (BBN)
Since the meeting in December 2009 techniques for summarizing risks and quantifying and communicating uncertainty in pest risk assessment were developed further in particular the Bayesian Belief Network (BBN).
A Bayesian network is a probabilistic model that defines various events (in our case the questions of the PRA schemes) , the dependencies between them, and the conditional probabilities involved in those dependencies. Conditional probability tables (CTP) are created by constructing tables that assign probability values to a combination. Ideally conditional probability tables should be developed by experts running the scheme. A BBN model was tested during the meeting and experts commented that it needed further improvement. It was noted that in order to develop conditional probability that reflect expert judgment, involvement of PRA experts was essential, this was considered as the main obstacle to its further development.


Environmental impact questions
A revision of the two questions of the scheme on environmental impact was presented. The objective of the revision is to provide more guidance on how to answer the individual questions and sub questions have been added. In the first question on the environmental impact in the current area of invasion, sub questions have been added to score 3 different categories of environmental impact (impact on native biodiversity, alteration of ecosystem patterns and processes, conservation impacts). When the impact can be evaluated for the area of invasion, then the assessor uses this evaluation to score the potential impact in the PRA area. If the impact cannot be evaluated for the area of invasion, then another set of sub questions is proposed. The Panel considered the revised questions on environmental impact very useful. It was agreed that they should be included within CAPRA to be further tested for future PRAs.


Pest risk mapping: climatic mapping
A draft climatic mapping decision support scheme was presented. The document is not intended to advise the expert which scheme to use, but it presents the implications of using a particular climatic model according to the situation. The first stage of the decision support scheme aims to consider whether it is appropriate to map climatic suitability on the basis of 4 yes/no questions, so as to allow a rapid assessment. The tools developed for the mapping will be included in the EPPO PRATIQUE PRA Workshop that will be held in November 2010.


WP 6 - Project validation and dissemination with the development of a web-based PRA scheme
The modifications made to the computer programme CAPRA (Computer Assisted PRA) which has been developed by the EPPO Secretariat were presented to the Panel. The computer programme is a web downloadable standalone version that has to be installed on individual computers. All sections of the EPPO Decision-Support Scheme for quarantine pests are included and hyperlinks to the definitions of terms of the Glossary of phytosanitary terms (ISPM No.5) are available. The different sections of the EPPO DSS can be performed independently and no longer need to be completed in a fixed sequence. The programme is at present only available for download to PRATIQUE partners, EPPO Panels and Expert Working Groups.