Transcript Pest Risk Assessment for Introduced Forest Pests

Pest Risk Assessment for Introduced
Forest Pests: Challenges Arising from
Scientific Uncertainty
Faith Thompson Campbell, Ph.D.
The Nature Conservancy, United States of America
My starting point: protection of the ecological integrity of
natural systems. I will also mention economic impacts.
Neither type of impact – to natural system or to economic
interests/stakeholders – is well documented. Full
documentation of ecological impacts might not be possible
because of complexity of forest systems and gaps in our
knowledge .
North America, Australia, and to a lesser extent Europe and Asia
have already suffered severe impacts from introduced forest insects
and pathogens. In several cases, these introduced organisms have
nearly eliminated entire species from the forest. Examples shown
are Castanea americana (chestnut blight), Cronartium ribicola
(white pine blister rust), Phytophthora cinnamomi (ink disease),
Ophistioma ulmi (elm disease), & Bursaphelenchus xylophilis
(pinewood nematode).
Rising trade volumes raise the risk – unless effective measures are
taken to prevent such introductions. Values at risk include such
traditional agricultural ones as commerical forestry & forest
products; nursery production; and maple syrup and other forest
products. Also at risk are non-agricultural values, including
economic & aesthetic values of our homes, municipal & private
tree removal & replacement costs, nature-based tourism, and the
ecological values of natural forests.
One of the purposes of the international phytosanitary system is
to prevent repetitions of these disasters. The system is
manifestly failing this test. Among the most prominent
introductions over the past 20 years are:
Anoplophora glabripennis - Asian longhorned beetle - North America & Europe
Agrilus planipennis - Emerald ash borer in North America
Tetropium fuscum - brown spruce longhorned beetle in North America
Bursaphelenchus xylophilis - pinewood nematode in Europe
Anoplophora chinensis - citrus longhorned beetle in North America (eradicated)
& Europe
Phytophthora ramorum - sudden oak death in Europe and North America
Sirex noctilio - woodwasp in North America
Phytophthora kernoviae - in UK
Phoracantha recurva - in Africa
Puccinia psidii - `ohi`a rust – in Hawai`i
IAS in natural systems are ecologically
different from agricultural pests
4 illustrations of differences:
1) In agriculture, plants & pests have usually co-evolved –
so usually some resistance (and managers know about
mitigation methods).
When pathogens are introduced into natural ecosystems,
and the pathogen and plant host have not co-evolved,
there is usually limited genetic resistance to infection in
host populations. Can be devastating results – virtual
elimination of tree species from the forest
D.M. Rizzo 2005. Exotic species and fungi: interactions with fungal,
plant and animal communities. pp. 857-877 in The Fungal Community,
edited by J Dighton, JF White, P. Oudemans. CRC Press
2) Impacts of introduced forest insects and diseases are
cumulative & long-lasting, with cascading effects
3) Control options are limited, “drastic” & of limited
efficacy … exacerbated by tardy detections
4) Management options can have severe ecological
impacts
Post-introduction response is costly, as is illustrated by
the U.S.’ experience with five forest pests - $50 million
in one year, and that falls far short of the need.
Nearly 400 forest pests are not under official control –
and that failure to act has consequences.
The key dilemma in international trade
agreements can be summarized as follows:
The potential magnitude of impacts & lack of effective mitigation
measures, combined with practical limits on the number of postentry eradication programs any country can carry out …
Point to establishing a very high Level of Protection &
appropriately stringent phytosanitary measures
However, the higher the level of protection and more stringent the
measures, the greater the specificity probably required in PRA.
In evaluating a pathway, how specific can scientists be in defining
which pests might be introduced, how likely such an introduction
might be, and how effective SPS measures will be in preventing
introductions?
How specific PRAs must be –
Key rulings of the WTO Appellate Body
European beef hormone case (AB-1997-4): PRA must
evaluate the carcinogenic potential of specific hormones at
the specific residue levels that would be found “in …
specifically, 'meat or meat products,'“ when the hormones
are “used specifically for growth promotion purposes”
[italics in original]
Australia/Salmon case (AB-1998-5): PRA must
(1) Identify the hazards and possible biological and economic
consequences of their entry or spread,
(2) Evaluate the likelihood of entry, establishment, or spread,
and
(3) Evaluate the impact of SPS measures on the likelihood of
entry, establishment, or spread of the hazards.
Japan-Apples (AB-2003-4):
• To defend any claim that a measure is intended to protect
against illegal shipments, document that illegal shipments
have occurred or are likely
• If adopting a systems approach, analyze the individual
efficacy of each component and defend the need to impose the
entire system.
• Analyze alternative approaches, not justify a pre-determined
approach.
Provisional measures (under Art. 5.7) may be adopted
only in certain, restricted, circumstances - Japan-Apples
• AB 1998-8 - must actively seek the missing information and
review the provisional measure within a reasonable period
• AB-2003-4 - not allowed when there is sufficient information
to complete a PRA – that is, to evaluate the likelihood of entry,
establishment or spread of the pest in question.
• “unknowns” do not equal “insufficient information”
• Issue not clarified:
– Whether the PRA must be country-specific
Conducting a “Pathway” PRA does not solve the
problems arising from demands for specificity Per Japan-Apples (AB-2003-4) and the proposed new IPPC
ISPM 2 (Steward Draft Version), a pathway PRA must still
attribute a specific likelihood of entry, establishment or
spread to each pest evaluated.
NAPPO Concept Paper - Plants for Planting
http://www.nappo.org/Standards/Consultation/RSPM24-ConceptPaper3-8-04-e.pdf
Documents that PRAs based on lists of known quarantine pests (as
most are) do not address numerous uncertainties:
-
many potential quarantine pest are obscure or unknown
-
pathogens are often poorly understood
-
pest impact on host and non-host plants is poorly understood
-
pest impact in native environment is an unreliable indicator of
its behavior in a new ecosystem
-
potential for genetic change or variability in pests or hosts
-
uncertain origins of the material or mother stock
Unknowns – potential pests
• The number of arthropods extant globally is unknown – estimates range
from a few million to ten million
• Experts estimate that 95% of fungal species remain undescribed
understudied fungal habitats include soil, leaves, roots; & the tropics
• Native ranges are unknown for many
Examples of forest pathogens for which the area of origin was unknown when
it was introduced:
• Cryphonectria parasitica
• Ophiostoma ulmi & O.novo-ulmi
• Phytophthora lateralis
• Discula destructiva
• Phytophthora cinnamomi
• Phytophthora ramorum
• Sirococcus clavigignenti-juglandacearum
• Phytophthora kernoviae
Weaknesses of Predictions
“There are currently no known broad scientific principles or reliable
procedures for identifying the invasive potential of plants, plant pests, or
biological control agents in new geographic ranges.”
National Research Council, Predicting Invasions of Non-indigenous Plants
and Plant Pests 9 (2002), available at
http://www.nap.edu/books/0309082641/html/
“We do not believe that pest risk assessments can adequately identify
organisms which may cause severe damage in North America.”
George C. Carroll, President, Mycological Society of America 1998. Letter to
Dan Glickman, Secretary of Agriculture.
Only 18% of insects and mites introduced in the U.S. behaved as expected
W.E. Wallner, 2004. Assessing Exotic Threats to Forest Resources. In K.O.
Britton, Editor. Biopollution: An Emerging Global Menace. APS Press
Evolution & Hybridization
• Risk of hybridization more widespread than appreciated - a
general biological phenomenon.
• Can be quite rapid
• Facilitated by trade, which brings geographically isolated but
related organisms into proximity
• Examples:
- Ophiostoma ulmi & O. novo-ulmi
- Phytopthora alni
- Melampsora
Clive Brasier (world expert on pathogens) has been warning
about this risk for a decade
Complexity of Receiving Systems
“ . . . forest ecosystems are highly complex, and most forest pests
are not thoroughly understood. As a result, the answers to the
key questions[1] often represent little more than speculation”
W.E. Wallner, 2004. Assessing Exotic Threats to Forest Resources. In K.O.
Britton, Editor. Biopollution: An Emerging Global Menace. APS Press
[1]These “key questions” are
1) What is the probability that the introduced species will be
harmful?
2) How harmful is the introduced species likely to be?
Quantifying Impacts
Quantifying the impacts of exotic species is often impossible or
difficult because of a lack of baseline ecological data on
invaded ecosystems. … [complexity of impacts affecting]
different spatial and temporal scales. … individuals,
populations, communities and ecosystems. Interactions …
may be positive, negative or neutral. … cumulative and
indirect effects / a cascade of changes throughout an
ecosystem. …
Rizzo DM. 2005. Exotic species and fungi: interactions with
fungal, plant and animal communities. pp. 857-877 in The
Fungal Community, edited by J Dighton, JF White, P.
Oudemans. CRC Press
Lack of economic valuation methods for non-commercial forest
values
Chornesky, Bartuska, Aplet, Britton, Cummings-Carlton, Davis,
Eskow, Gordon, Gottschalk, Haack, Hansen, Mack, Rahel,
Shannon, Wainger, Wigley. “Science Priorities for Reducing the
Threat of Invasive Species to Sustainable Forestry”
Bioscience April 2005 Vol. 55 No. 4
Recommendations:
 Allow pathway PRA to support pathway regulations that
apply to all potential IAS using the pathway, not just
those analyzed individually
could be hundreds or even thousands of species using
the pathway; no country has sufficient resources to do
the numerous “catch-up” PRAs that would be required
to apply the pathway measure to each “new” pest as a
provisional measure under Article 5.7
 Allow countries adopting policies aimed at countering
newly recognized risks to the environment (as distinct
from agriculture) to utilize provisional measures under
Article 5.7 - so can close off these pathways promptly.
The risk level is simply too high to delay.