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 & EuropeAgrilus planipennis - Emerald ash borer in North AmericaTetropium fuscum - brown spruce longhorned beetle in North AmericaBursaphelenchus xylophilis - pinewood nematode in EuropeAnoplophora chinensis - citrus longhorned beetle in North America (eradicated)

& EuropePhytophthora ramorum - sudden oak death in Europe and North AmericaSirex noctilio - woodwasp in North AmericaPhytophthora kernoviae - in UKPhoracantha recurva - in AfricaPuccinia 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 post-entry 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 undescribedunderstudied 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.