Pest Risk Analysis (PRA) Stage Pest Risk Analysis (PRA) Stage 2: Pest Risk Assessment2: Pest Risk Assessment

Pest Risk Analysis (PRA) TrainingPest Risk Analysis (PRA) Training

Stages

• Stage 1: Initiation• Stage 2: Pest Risk Assessment

– Step 1: Pest Categorization– Step 2: Assessment of the Probability

of Introduction (entry, establishment) and Spread

– Step 3: Impacts– Step 4: Overall Assessment of Risk– Step 5: Uncertainty

• Stage 3: Pest Risk Management

• Perpetuation, for the foreseeable future, of a pest within an area after entry (ISPM 5, 2007)

Establishment

Pest

Host (Habitat)

Environment(Ecosystem)

• Collect information from area(s) where pest occurs & PRA area– Pest information– Environment information– Host information

• Compare• Assess probability of establishment

Probability of establishment

• Availability of suitable hosts, alternate hosts and vectors

• Suitability of environment, including biotic & abiotic factors

• Cultural practices and control measures

• Other characteristics affecting probability of establishment

Factors to consider…

• Are hosts & alternates present? • Are habitats available for pest

plants?• How likely is the pest to find hosts?

Are they abundant? • Are hosts present in the vicinity of

expected entry points?

Host information

• Is the pest adaptable? • Has it been introduced elsewhere? • Can it adapt to different climatic or

other environmental factors? • Can the pest seek out hosts? Is it

mobile?

Pest information

• How does the pest reproduce? Does it have a high reproductive capacity?

• How does it survive adverse conditions?

• Does it require an alternate host or a vector?

Pest information

• Is a vector required for dispersal of the pest? – Is it present in the PRA area? – Is it likely to be introduced? – Are other potential vectors available?

Vector information

• Does the climate in the PRA area differ from that where the pest occurs? How?

• What climatic factors are critical for the pest’s success? What climatic factors, if any, are limiting?

• Is the climate suitable for the pest? Will it be able to survive? Will it be able to reproduce?

Climate information

Climate information

• Precipitation– Rain, snow, fog ….

• Temperature– Seasonal highs and lows, temperature

extremes …

• Seasonal variation

Other environmental information

• Soil• Hydrology• Vegetation• Prevailing winds• Day length• Species interactions

Cultural practices and control measures

• Compare cultivation practices of host crops in the area of origin and PRA area

• Would existing practices mitigate risk?• Are there any pest control programs or

natural enemies already in the PRA area?

• Are suitable methods for pest control or eradication available?

Other factors

• Reproductive strategy and method of pest survival – Self-crossing– Duration of life cycle– Generations per year

• Genetic adaptability• Minimum population needed for

successful establishment

Establishment

Pest

Host (Habitat)

Environment(Ecosystem)

Tools for predicting establishment

• Plant hardiness zone maps

• Climate maps• Climate-matching

models• Bio-climatic models

• Fit for purpose• Science-based• Transparent

Modelling systems

• Examples– CLIMEX– GARP– BIO-CLIM

• Distribution and abundance of an organism that cannot regulate its body temperature is largely determined by climate

• Climate information from the known distribution of an organism can help predict the potential distribution and abundance of the organism in new regions

Environmental factors

• The distribution and abundance of an organism that cannot control or regulate its body temperature is largely determined by climate.

• Climate information from the known distribution of an organism can help predict the potential distribution and abundance of the organism in new geographic regions.

CLIMEX

• Computer software containing long term data (30 years) from almost 3000 locations worldwide

• Is used to predict the effects of climate on plants and animals based on biological parameters e.g. response to temperature

• Generates a single number – the Eco-climatic Index to describe how favourable a location is for a particular species

Asian Longhorn BeetleAnoplophora glabripennis

• Native to China, pest of poplar trees

• Introductions in USA & Canada• PRA initiation for UK – spread

outside PRA area

Distribution in Asia

CLIMEX indices for ALB in Asia

CLIMEX Indices for ALB in Europe

Computerized predictive models

• Useful communication tool • Predictive maps based on limited climate

variables • Does not include host information or other

interactions• Involves subjective judgements &

assumptions• May cause false confidence

Suitability of environment

• Aphis nerii found at a nursery on imported plants

• Damages plants and vectors several viruses

• Polyphagous • Temperature requirements

known• Establishment in a protected

environment possible?

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5.0

10.0

15.0

20.0

25.0

30.0

35.0

1 31 61 91 121 151 181 211 241 271 301 331 361

Julian date

Te

mp

(C

)

Heated max Heated min Outdoors max Outdoors min

Temperature data in relation to Aphis nerii development

Red = threshold temperature for development of Aphis nerii (8.2C)

Blue = outdoor maximum and minimum temperature data southern England

Black = maximum and minimum temperature in a heated glasshouse.

Sources of information• NPPO• RPPO• Atlases• WWW• FAO• CABI• Books• National government

data• Journals

• PRA area• Pest’s

current distribution

Establishment

Pest

Host (Habitat)

Environment(Ecosystem)