Evaluating the potential
impacts
of invasive species
Chris Baddeley
Policy Manager
Biosecurity New Zealand
Overview
Purpose of evaluation
Method of evaluation
Presentation of results
Examples
• Painted apple moth
• Didymo
• Other New Zealand examples
2
Purpose of impact evaluation
Contributes to decisions on:
• whether to respond to a new or existing pest
• the scale of any response
Forms a key part of the business case for new funding from
Government (or industry) for a pest response
3
Purpose of impact evaluation
In New Zealand pest response decisions based on:
• technical feasibility
• economic justification
• priority for action
Impact evaluation needed to help determine economic justification
and priority for action.
Also used for communications purposes.
4
Method of evaluation
Assess quantifiable pest impacts in the
absence of Government intervention (to
determine potentially avoidable costs)
Develop scenarios around the likely range
of impacts. Key factors are:
• any likely limits on
geographical spread
• likely rate of spread
• impacts by sector
5
Methods of evaluation
Research what is known about the pest (often not a lot for new
invaders)
Use experts panels to:
• bridge knowledge gaps (best expert opinion)
• provide advice/opinions on likely rate of spread and
geographical limits to spread
• develop scenarios of potential sector impacts
• form expert views on likely pest impacts (forecasting methods
such as Delphi process)
6
Methods of evaluation
Also use expert panels to:
• form views on feasible options for response
• form views of likely effectiveness of treatments
Some requirements for an expert panel:
• knowledge of all affected sectors
• expertise in all relevant disciplines
• effective teamwork, listening, building on views of others
• no conflicts of interest/maintain confidentiality
7
Methods of evaluation
Impacts can be:
• reduced productivity
• damage to natural values (eg. wildlife)
• damage to social values (eg. recreation
and amenity)
• new or increased pest treatment costs
• the need to adapt to the pest (eg. resistant crops, less preferred
species)
• increased management costs
15
Generally exclude impacts that are too small or too uncertain from
numerical assessment (including intangibles).
8
Methods of evaluation
Good resource information is the key to reliable estimation of impacts
• forest estate models or inventories
• urban trees databases
• agricultural and horticultural statistics
• commodity values and trade data
• value mapping
Also information on likely adaptive behaviour by industry, landowners
and the public
9
Methods of evaluation
Can undertake some short-term research to gain further
information:
• host plant testing
• life-cycle modeling
• ecological research
• dispersal rates (sterile insects release, pheromone
development)
10
Presentation of results for decision-making
Impacts generally determined as a stream of costs stretching into
the future
Impacts generally presented as a “present value” (discounted).
Need to determine time-scale for assessment. Options include:
• point where additional impacts are not material
• a pre-determined time (investment return period)
• time until pest occupies is full potential range
• time until the pest is next expected to establish (re-incursion)
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Presentation of results for decision-making
Results can be expressed as:
• present values over given period (eradication)
• annual value once range fully occupied (on-going management).
Also:
• sensitivity analysis used to show influence of different assumptions
• inclusions and exclusion need to be clearly stated along with any
key qualitative information
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Example – Painted Apple Moth (Teia anartoides)
Limits on geographical spread
Rate of spread:
None
Throughout Auckland region in ten years
Throughout rest of New Zealand in fifteen years
Impacts modeled
• urban households (additional spending on spraying)
• urban golf courses and school ground (additional spending on spraying)
• public land in urban areas (accelerated tree removal and replacement)
• plantation forests (spraying costs and reduced growth rate)
• horticulture – apples (increased spraying)
13
Example – Painted Apple Moth
Distribution of present value total impacts 2002/03 to 2021/22: New Zealand
Sector
14
Impacts ($ million)
Low
Medium
High
Urban households
3.5
11.0
23.8
Urban gold courses and school
grounds
0.3
0.8
1.7
Urban public land (streets, parks
and reserves)
9.3
16.2
47.6
Total urban area impacts
13.1
28.0
47.6
Plantation forestry (radiata pine)
45.2
129.0
308.0
Horticulture (apples)
0.2
0.2
0.2
Total
58.5
157.2
355.0
Example – Painted Apple Moth
Impacts not modelled (small or too uncertain)
• impacts on natural forests
• impacts of soil and water conservation
• impacts on market access
• impacts on human health
15
Example - Didymo
Limits on geographical spread
Potentially affects a high
percentage of high-order river reaches in all regions
Rate of spread:
Throughout NZ within 7 years of detection
Impacts modeled:
• commercial eel fisheries
• water intakes
• drinking water
• local recreation values
• tourism expenditure
• local and national existence values
• existence values associated with endangered native species
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Example - Didymo
Sector
17
Impacts
Low
Medium
High
Commercials eel fisheries
Loss of annual return
5%
10%
20%
Water intakes
Self cleaning screens on intakes
50%
75%
95%
Drinking water
Carbon filters
20%
30%
40%
Recreational values reduction (per
household per year)
•Fishing $21.48
•Boating $40.65
•Other recreation $9.20
20%
5%
10%
50%
0%
20%
80%
20%
50%
Tourism expenditure reduction
•Domestic
•International
1%
2%
2.5%
5%
5%
10%
Example - Didymo
Sector
Existence values of rivers
$105.28 per household per
year
•Reduction for local regional
rivers
•Reduction for other regions
rivers
Loss of native species
$23.16 per household per
year for loss of a native fish
species in local region
(1/5 of this for loss of species
in another region)
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Impacts ($ million)
Low
Medium
High
2.5%
5%
10%
0.5%
1%
2%
1 species
2 species
3 species
Example - Didymo
Present Value Total Impacts 2004/05 to 2011/12
Sector
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Impacts ($ million)
Low
Medium
High
Commercials eel fisheries
0.019
0.237
0.525
Water intakes
10.785
21.834
27.656
Drinking water
3.048
7.716
10.288
Recreational values
12.706
49.102
88.248
Tourism expenditure
6.091
31.747
63.493
Existence values
6.875
20.051
40.102
Loss of native species
18.273
36.547
54.824
Total
57.798
167.233
285.132
Example - didymo
Impacts not assessed:
•
•
•
•
20
cultural values including customary fisheries
alluvial gold mining
exports of used fishing and boating gear
human health (eye irritation and injuries for slipping on
rocks)
Significant biosecurity incursions – New Zealand
examples 1996 - 2006
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Incursion
When
Outcome
Potential economic impact
Estimated cost to
Crown
Whitespotted
tussock moth
1996
Eradicated
Unquantified impacts on urban
amenity plantings and
horticultural production
$12.4 million
Varroa bee
mite
2000
Widely established in
the North Island.
National Pest
Management
Strategy
implemented to keep
South Island varroa
free.
Present value impact estimated at
$316 million over the next 35
years
Estimated $10
million
Red imported
fire ant
2001
Eradicated
Present value impacts estimated
at $665 million over the next 23
years.
$2.600 million
Asian gypsy
moth
2003
Eradicated
Present value impact estimated at
$190 million to 20045.
$5.200 million
Significant biosecurity incursions – New Zealand
examples 1996 - 2006
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Incursion
When
Outcome
Potential economic
impact
Estimated cost to Crown
Fall webworm
moth
2003
Current indications are
that eradication has been
achieved. Monitoring
continues.
Present value impact
estimated at $33.5
million over 20 years.
Didymosphenia
fresh water alga
2004
Response ongoing.
Present at several South
Island locations, but as
yet no detections in
North Island.
Eradication not possible.
Preliminary present
value impact estimated
at between $55 million
and $367 million over 7
years.
$5.337 million (to date)
Sea Squirt marine
fouling pest
2005
Response ongoing.
Widely established in
Hauraki Gulf, and
present at several other
locations. Eradication
not possible.
Present value impact
estimated at between
$46 million and $239
million over 21 years.
$3.033 million (to date)
$7.850 million
Significant biosecurity incursions – New Zealand
examples 1996 - 2006
Incursion
When
Outcome
Potential economic
impact
Estimated cost to
Crown
Clover root
weevil
1996
Spreading through
the North Island.
Biological control
agent identified need
for increased
nitrogen application.
Present value impact
estimated at between
$1.4 billion and $8.1
billion over 35 years.
About $10 million
invested in
research and
information/advice
Not present
Loss in GDP of $10
billion after 2 years
with significant ongoing costs.
Significant
investment in
disease response
preparedness
Foot and mouth
disease
23
Not
present