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RMD-19-02: Pest Risk Management Document for the deregulation of Tomicus piniperda (pine shoot beetle)

Effective date: November 4, 2020


As described by the International Plant Protection Convention (IPPC), Pest Risk Analysis (PRA) includes three stages: initiation, pest risk assessment and pest risk management. Initiating the PRA process involves identifying pests and pathways of concern and defining the PRA area. Pest risk assessment provides the scientific basis for the overall management of risk. Pest risk management is the process of identifying and evaluating potential mitigation measures which may be applied to reduce the identified pest risk to acceptable levels and selecting appropriate measures.

This Risk Management Document (RMD) includes a summary of the findings of a pest risk assessment and records the pest risk management process for the identified issue. It is consistent with the principles, terminology and guidelines provided in the IPPC standards for pest risk analysis which may be found at the International Plant Protection Convention website. It is also important to note that Pine Shoot Beetle has been established in Canada for more than twenty years, and this RMD serves to evaluate the effectiveness and benefit of the existing measures.

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Executive summary

Tomicus piniperda (pine shoot beetle), is an invasive forest pest that has been in North America for almost forty years, and has been under official control in both the United States and Canada, since it was first found. There were concerns when the pest was first introduced that it would spread and be damaging to valuable pine forests that are important to Canada's forestry sector. However, twenty years after its establishment, there is little evidence to suggest that pine shoot beetle has caused significant damage to native pine stands. Pinus sylvestris (Scots pine), its main host, is not native to the Americas and was only attacked in plantations when under stress.

Additionally, not all pine species in North America are equally easy for the beetle to attack, and none are as favoured by the beetle as is the non-native Scots pine. Hard pines seem to be preferred over soft pines for egg-laying and larval feeding. Some other types of conifer are attacked every once in a while, but they are not true hosts, and are not preferred by the beetle. Most attacks fail, even on stressed trees, and in general, only trees in an advanced state of decline die after beetle attack, with drought and other sources of tree stress adding to the chance of successful attack. The reasonable conclusion is that it is a secondary pest that attacks weak and dying trees, and therefore aids in the recycling of the forest.

The beetle is likely to expand its range in Canada to eventually occupy the entire coniferous and mixed forest. Human-assisted spread is possible, especially in logs with bark, firewood with bark, and nursery stock, depending on the time of year and size of the nursery stock.

An economic analysis by the United States, and a similar study by Canada, showed that the cost of regulation is greater than the benefits of controlling the beetle. The United States is in the process of deregulating the beetle, effectively removing all controls limiting its spread through human actions.

Following consultation and due consideration of stakeholder feedback, the Canadian Food Inspection Agency (CFIA) is deregulating Tomicus piniperda in Canada and communicating the decision through this RMD. The deregulation is not expected to cause any significant market access issues with the United States since that country has also decided to deregulate pine shoot beetle as of November 2, 2020, resulting in the removal of domestic regulations in addition to import restrictions that apply to the importation of Pine Shoot Beetle (PSB) host material from Canada.

Directive D-94-22: Plant Protection Requirements on Pine Plants and Pine materials to Prevent the Entry and Spread of Pine Shoot Beetle, which outlines the phytosanitary requirements for the importation of PSB host material from the continental United States, as well as its movement within, and exportation from Canada to the continental United States, will be revoked.

1.0 Purpose

The purpose of this document is to communicate the CFIA's risk management decision to deregulate Tomicus piniperda (pine shoot beetle) in Canada.

2.0 Scope

This pest Risk Management Document (RMD) pertains to Canada's regulations and programs (plant import and domestic movement) with respect to Tomicus piniperda. It also provides the history and scientific rationale as to why the CFIA has decided to deregulate this pest.

3.0 Definitions

Definitions for terms used in this document can be found in the Plant Health Glossary of Terms.

4.0 Background

Circumstantial evidence suggests that Tomicus piniperda (pine shoot beetle), probably became established in the northeastern United States sometime in the 1980's, and that there were at least two separate introductions (Carter 1996; Haack 1997). The beetle was first reported in Canada in 1993 in the Niagara Peninsula and subsequent surveys that same year found it in 7 counties in southern Ontario (Favrin and Howse 1998). Since then it has spread across Ontario and Quebec, so that the regulated area includes all counties from Sault Ste-Marie, Ontario, east along the Ottawa and St. Lawrence Rivers to Temiscouata on the New Brunswick border, and south to the U.S. border (see the list of pine shoot beetle infested areas in Canada and the United States). In the United States, the pest has established itself throughout the northeast and north central states, from Minnesota to Maine, south into northern Missouri, Maryland and West Virginia, Pine shoot beetle North America quarantine area.

5.0 Pest risk assessment summary

A pest risk assessment for Canada was conducted in 1999 and updated in 2012. New information at the time of the initial assessment suggested that most North American pines are potential hosts for the pine shoot beetle, and that Pinus resinosa (red pine), Pinus banksiana (jack pine), and Pinus ponderosa (ponderosa pine), are attractive hosts for the pest. In addition, its native host, Pinus sylvestris or Scots pine is particularly attacked in North America as it is in its native range in Europe, Asia and North Africa. Pinus strobus (white pine) is a less suitable host, but is still attacked. The beetle is able to survive throughout the range of pine forests of Canada, and of North America generally, including the boreal forest. Establishment potential was considered high. However, its rate of natural spread is relatively low compared with other pests. The reported death of native pines in Ontario precipitated the renewal of the risk assessment, but the assessment still determined that it was unlikely that native pines would be killed unless they were near a heavily-infested stand of non-native Scots pine. Since that time, there has been no further direct evidence that this beetle is a primary pest that can kill healthy trees, or cause significant additional mortality of native pines in Canada. In addition, the Christmas tree industry is moving away from non-native Scots pine in preference to other species.

5.1 Pest biology

5.1.1. Life history

Tomicus piniperda is a beetle in the family Curculionidae (the weevils), subfamily Scolytinae (the bark beetles), that feeds on and reproduces in living and freshly-cut pines as well as the cut stumps. Adults leave their overwintering sites and fly on the first warm and dry days of the spring, when daily maximum temperatures reach 10 to 12°C and the daily mean temperature is 7 to 8°C (Humphreys and Allen 1998). Adults search for weakened or stressed trees, or cut pine stumps or logs in which to lay their eggs (Haack and Poland 2001). Once on a suitable host, the adults excavate galleries under the bark to lay eggs. After the beetles finish laying eggs, they emerge from the egg gallery and die. From April to June, larvae feed in separate galleries that are 2.5 to 10 cm long. The larvae finish feeding in May or June, pupate and transform into adults at the end of their feeding gallery (Humphreys and Allen 1998). The new adults emerge through the bark and attack new shoots on pine trees of all ages. The shoots on current year twigs are burrowed up to 10 cm through the pith. In October, the adults exit the twigs and move into the soil or the bark at the base of pine trees to overwinter; in warmer climates they can also overwinter in the crown shoot tunnels (Haack and Poland 2001). The timing of the life cycle of the pine shoot beetle is very dependent on the local climate. Snow pack adds insulation and aids survival in colder climates. Larvae are killed by temperatures below -12°C. Pupae and adults die at temperatures below -18°C (Humphreys and Allen 1998).

5.1.2. Host range

In a European study, field experiments were carried out in France and in Sweden and observations of attack density of pine shoot beetle were recorded on some pines species of relevance to Canada. In France, the Canadian pine species that proved suitable as host material were, in descending order of preference: Pinus ponderosa Lawson (ponderosa pine), P. banksiana Lamb. (jack pine), and P. contorta Douglas (lodgepole pine). Pinus resinosa Sol. ex Aiton (red pine) and P. strobus L. (eastern white pine) were not attacked at all in France, whereas in Sweden, eastern white pine, lodgepole and jack pine were attacked but at a much lower attack rate than Scots pine (Långström et al. 1995). In North America, eastern white pine is attacked only when beetle populations are high (Humphreys and Allen 1998).

The southern pines: Pinus taeda L. (loblolly pine), Pinus echinata Miller (shortleaf pine), Pinus elliottii var. elliottii Engelmann (slash pine), Pinus palustris Miller (longleaf pine), and Pinus virginiana Miller (Virginia pine), and two western pines: Pinus ponderosa Lawson (ponderosa pine) and Pinus contorta Douglas (lodgepole pine), were shown in a third study to be acceptable breeding hosts, although brood production in these hosts is highly variable. Loblolly and shortleaf pine are susceptible to shoot feeding, whereas slash pine is highly resistant and longleaf seems to be virtually immune as all attacking beetles are ejected by pitch flows (Eager et al. 2004).

In short, the pine shoot beetle can live on most pine species but hard pines are preferred over soft pines for egg laying and brood production, while the beetle is less discriminating when feeding on shoots. Other conifers are occasionally attacked, but cannot be regarded as hosts. Abies balsamea (L.) Mill. (balsam fir), Picea abies (L.) H. Karst. (Norway spruce), Larix (larch), and Pseudotsuga menziesii (Mirb.) Franco (Douglas fir) are all recorded as ‘hosts' when populations are high (CABI 2018; Humphreys and Allen 1998).

5.1.3. Distribution

The pine shoot beetle has an extremely wide geographical distribution, extending from Portugal in western Europe to Japan in Asia, and from the timberline beyond the Arctic circle in northern Europe to northern Africa in the south (CABI 2018). As of 2019, in Canada and the U.S. it is found from Minnesota and Ontario across to Maine and Quebec, and south into northern Missouri across to the Atlantic coast. So far it has remained north of Kentucky and all but the northern few counties of Virginia, and has not been recorded from Delaware (USDA 2016).

5.2 Pathways for entry, establishment and spread

5.2.1. Entry potential

Several pathways have been identified and assessed in the risk assessment for the pine shoot beetle. Those of consequence are:

Crating, pallets, firewood and dunnage (of pine)

Given the implementation of the International Standard for Phytosanitary Measures No. 15 (ISPM 15), entitled Regulation of wood packaging material in international trade, the risk associated with this pathway has been reduced to low.

ISPM 15 is not currently applied to trade between Canada and the United States, so untreated solid wood packaging made in the United States could move to Canada, and vice-versa.

Logs (of pine)

Pine logs from off-continent are refused entry pending a Pest Risk Assessment (PRA). A PRA is required to evaluate the plant health risk posed by the commodity, to determine the efficacy of proposed treatment options and to identify any known pests potentially associated with the logs. Regarding imports from the continental United States, there will no longer be the need for regulations since both the United States and Canada will be deregulating pine shoot beetle at about the same time.

Nursery stock of pine species

The likelihood of beetles being transported in this pathway depends on the size of the nursery stock and the time of year. Immature stages of the insect would not likely be associated with healthy young pines for planting, that are less than 2 cm. in diameter, but adults could be conducting maturation feeding in the shoots, even in the spring. Some adults begin to shoot-feed early in the year. Adults could also be hibernating in bark at the base of the trees, if the bark is thick enough to provide a suitable site. However, young trees less than 2 cm in diameter are unlikely to provide suitable overwintering sites; larger specimens could have bark that is thick enough.

Pine Christmas trees and other non-propagative Christmas articles

No off-continent Christmas trees are imported. The likelihood of overwintering beetles being on harvested North American-sourced Christmas trees or other non-propagative Christmas articles, is mitigated by the application of existing phytosanitary procedures by growers in both the United States and Canada. In addition, beetles that remained in trees brought indoors could emerge and continue feeding. But upon removal of the tree from the house post-holidays, they would most likely succumb to the ambient cold temperatures.

5.2.2. Establishment potential

This beetle has already shown that it is capable of establishing in Canada, and surviving in very cold areas of Europe and Russia.

5.2.3. Spread potential

Adults can fly for several kilometers to find a suitable host (Humphreys and Allen 1998), although the usual distance when hosts are available is less than a half kilometre, with greater distances in the direction of the prevailing wind (Barak et al. 2000). Annual spread from all sources has been estimated to be approximately 16.5 km/year (90% confidence interval 14.0 to 19.2; Evans 2016) with an annual natural dispersal distance of approximately 900 m (Barak et al. 2000).

5.3 Potential economic and environmental consequences

The pine shoot beetle has been in North America since the 1980s. It was not recognized as present until about a decade after its arrival, probably because the shoot-feeding damage in Christmas tree nurseries resembles that caused by native pests (Haack et al. 1997). The damage the beetle causes in Christmas tree plantations, particularly poorly-managed plantations (Haack and Poland 2001), seems to be the only economic harm caused directly by the beetle. A 2004 study indicated that it should be classified as a secondary pest that attacks only recently-dead pine trees or trees suffering from severe stress, as most attacks (91%) failed, even on low-vigour pines. Trees that succumbed were already more than 50% denuded from other causes and otherwise weak and not able to pitch out attacking beetles (Morgan et al. 2004). In 2012, the risk assessment update reported that "At present all mortality is associated with the nearby presence of stressed Scots pine and it is still not clear that native pines would be able to support a killing outbreak in the absence of Scots pine."

An economic assessment of the value of regulation concluded that "under conservative assumptions, it is very unlikely that the current regulatory program is beneficial. Assuming conservatively low cost estimates of regulation and high estimates of area that might be impacted by the pine shoot beetle, there is only a 7.5%-17.4% chance that the program is generating a net benefit, depending on spread rates. Break-even analysis indicated that a much higher mortality rate than supported by current scientific literature and expert opinion would be required for the program to pay for itself."

Bogdanski et al. 2018). Their evaluation assumes that spread of the pine shoot beetle, which is primarily human-assisted, into the boreal forest north of southern Manitoba, would not occur based on current logging practices and road networks. They therefore did not consider harm to the Prairie Boreal and more western forests. However, there is no reason to suppose that it should be more harmful there than in the Great Lakes forested area, where it has only affected Scots pine nurseries, and native trees near highly infested Scots pine nurseries.

6.0 Risk management considerations

6.1 Plant protection regulations and associated directives

Tomicus piniperda (pine shoot beetle) is included in the List of pests regulated by Canada, and in Schedule II (Restricted Movement within Canada) of the Plant Protection Regulations.

6.2 Standards of the International Plant Protection Convention (IPPC)

The International Plant Protection Convention (IPPC) is an international plant health agreement that aims to protect cultivated and wild plants by preventing the introduction and spread of pests. It is recognized by the World Trade Organization as the standard-setting body for plant health. According to the IPPC, contracting parties shall not require phytosanitary measures for non-regulated pests. To be regulated, a pest must meet the definition of either a quarantine pest or a regulated non-quarantine pest. The definition of regulated non-quarantine pest does not apply to PSB.

To be considered a quarantine pest, according to the IPPC's definition (ISPM 5), an organism must be "a pest of potential economic importance to the area endangered thereby and not yet present there, or present but not widely distributed and being officially controlled."

ISPM 11, entitled Pest Risk Analysis (PRA) for quarantine pests, provides the details for determining the status of a pest. As stated in ISPM 11, the initial estimates within a PRA process are based on hypothetical situations. Over time, the status of the pest should be reviewed.

For a plant pest to be deemed to have potential economic importance, the following criteria should be met:

Over the last 20 years, Tomicus piniperda, has become widespread in eastern Canada and no longer qualifies as a pest of quarantine concern. This indicates that the current regulations have not been effective in controlling the establishment and spread of the pest, and are no longer warranted.

6.3 Pest status and trade in the United States of America

The pine shoot beetle is firmly established in Canada and the United States. It was first observed in the early 1980s, and its invasion has progressed well beyond any opportunity to eradicate it. Despite more than 20 years of regulatory control efforts in both the United States and Canada, it has spread throughout eastern North America, yet there is no evidence that it has reached outbreak levels in North America (Fowler et al. 2015; Haack and Poland 2001). It is acting as a secondary pest in the native forest, contributing, as do many other insects, to the natural cycle of plant degeneration and renewal.

On September 20, 2019, the United States Department of Agriculture informed Canada that it intends to lift the domestic quarantine for pine shoot beetle. Therefore, trade with the United States will not be affected should Canada also de-regulate the beetle. If Canada continues to regulate it, then Canadian producers of products that are based on host trees may encounter higher operating costs within the pest-free area relative to those within the areas already infested. This is due to current phytosanitary measures that are required in those areas.

6.4 Trade and economic impacts

The economic risk assessment indicates that the pine shoot beetle is not a pest of significant economic importance in Canada (Bogdanski et al. 2018). Deregulation of the pine shoot beetle is not expected to negatively affect the volume of host plants moving in trade.

Taking into consideration all available information, the pine shoot beetle appears to be acting as a secondary pest in North America, and is a primary pest only around Scots pine plantations. The reduction in demand for Scots pine as a Christmas tree will further limit the potential harm this insect can do. Therefore, given its 40-year history of low to no economic and environmental harm in North America, there is insufficient reason for retaining it as a quarantine pest.

To meet regulatory requirements for the pine shoot beetle, CFIA resources have been used to deliver survey programs and to inspect and manage the movement of potentially infested material through Canada and to the United States. Industries shipping host trees or potentially infested materials to un-infested areas of Canada have been required to implement phytosanitary programs and pay associated fees. Releasing the pine shoot beetle from regulated status will relieve industry of these costs.

7.0 Risk Management Decision

7.1 Consultation

The initial RMD, proposing to deregulate Tomicus piniperda (pine shoot beetle) across Canada, was circulated for stakeholder consultation in July 2019, and stakeholder feedback was received. Stakeholders from all provinces expressed support for the deregulation of pine shoot beetle.

7.2 Decision

Tomicus piniperda (pine shoot beetle) no longer meets the definition of a quarantine pest, according to ISPM 5. In addition, review of the regulatory approach to this pest, as outlined in Section 5.3 of this document, concludes that continued regulation will likely not provide any economic benefit.

Therefore, the CFIA will be deregulating pine shoot beetle. As a result, the CFIA will no longer enforce the import regulations that apply to pine shoot beetle host material from the continental United States. Additionally, the CFIA will not be enforcing the part of Schedule II (2) of the Plant Protection Regulations (PPR) that pertains to the domestic movement restriction of pine shoot beetle infested material. The United States has also decided to deregulate pine shoot beetle, resulting in the removal of domestic regulations, in addition to import restrictions that apply to the importation of pine shoot beetle host material from Canada.

The implementation of the deregulation of pine shoot beetle will require that relevant plant health import directives be amended to remove reference to requirements for freedom from pine shoot beetle, or revoked. The Automated Import Reference System (AIRS) will also be updated to reflect the deregulation of pine shoot beetle.

The CFIA will also work towards the removal of pine shoot beetle from the List of pests regulated by Canada, and Schedule II (2) of the Plant Protection Regulations.

8.0 References

Barak, A. V., McGervy, D. and Tokaya, G. 2000. Dispersal and re-capture of marked, overwintering Tomicus piniperda (Coleoptera: Scolytidae) from scots pine bolts. Great Lakes Entomologist 33:81-105.

Bogdanski, B. E. C., Corbett, L., Dyk, A. and Grypma, D. 2018. Pine shoot beetle, Tomicus piniperda (Linnaeus): Analysis of regulatory options for Canada. Canadian Forest Service Pacific Forestry Centre information report BC-X-443. The Pacific Forestry Centre, Natural Resources Canada, Victoria, British Columbia.

Brockerhoff, E. G., Knížek, M. and Bain, J. 2003. Checklist of indigenous and adventive bark and ambrosia beetles (Curculionidae: Scolytinae and Platypodinae) of New Zealand and interceptions of exotic species (1952-2000). New Zealand Entomologist 26:29-44.

CABI. 2018. Invasive Species Compendium. [Online] [2018].

Carter, M. C. A., J.L. Robertson, R.A. Haack, R.K. Lawrence and J.L. Hayes. 1996. Genetic relatedness of North American populations of Tomicus piniperda (Coleoptera: Scolytidae). Journal of Economic Entomology 89:1345-1353.

Drysdale, D. 1998. Impact on the Christmas tree industry: a grower's perspective Pages 19 in K. L. Ryall, S. M. Smith, eds. The Pine Shoot Beetle in Ontario. Faculty of Forestry, University of Toronto, Toronto, Ontario .

Eager, T. A., Berisford, C. W., Dalusky, M. J., Nielsen, D. G., Brewer, J. W., Hilty, S. J. and Haack, R. A. 2004. Suitability of some southern and western pines as hosts for the pine shoot beetle, Tomicus piniperda (Coleoptera: Scolytidae). Journal of Economic Entomology 97(2):460-467.

Evans, A. 2016. The speed of invasion: Rates of spread for thirteen exotic forest insects and diseases. Forests 7(5):99.

Favrin, R. and Howse, G. 1998. History and surveys for the pine shoot beetle in Ontario. Pages 5-9 in K. Ryall, S. M. Smith, eds. The pine shoot beetle in Ontario. Faculty of Forestry, University of Toronto, Toronto, Ontario.

Fowler, G., Takeuchi, Y., Vo, T. and Garrett, L. 2015. Pine shoot beetle, Tomicus piniperda (Linnaeus): Analysis of regulatory options. United States Department of Agriculture, Animal and Plant Health Inspection Service, Plant Protection and Quarantine, Center for Plant Health Science and Technology, Plant Epidemiology and Risk Analysis Laboratory, Raleigh, North Carolina.

Haack, R. A. 1997. Early history and spread of Tomicus piniperda in North America. Pages 146-153 Proceedings of the Japanese beetle and pine shoot beetle regulatory review, Louisville, Kentucky, 24-25 February 1997. USDA, Animal and Plant Health Inspection Service, Riverdale, Maryland, Louisville, Kentucky.

Haack, R. A., Lawrence, R. K., McCullough, D. G. and Sadof, C. S. 1997. Tomicus piniperda in North America: An integrated response to a new exotic scolytid. Pages 62-72 in J. C. Grégoire, A. M. Liebhold, F. M. Stephen, K. R. Day, S. M. Salom, eds. Proceedings: Integrating cultural tactics into the management of bark beetle and reforestation pests USDA Forest Service General Technical Report NE-236.

Haack, R. A. and Poland, T. M. 2001. Evolving management strategies for a recently discovered exotic forest pest: The pine shoot beetle, Tomicus piniperda (Coleoptera). Biological Invasions 3(3):307-322.

Humphreys, N. and Allen, E. A. 1998. The pine shoot beetle: Exotic Forest. Pest advisory no. 2. Canadian Forest Service, Pacific Forestry Centre, Victoria, British Columbia.

Långström, B., Lieutier, F., Hellqvist, C. and Vouland, G. 1995. North American pines as hosts for Tomicus piniperda (L.) (Col., Scolytidae) in France and Sweden. Pages 547-557 in F. P. Hain, S. M. Salom, W. F. Ravlin, T. L. Payne, K. F. Raffa, eds. Behavior, population dynamics and control of forest insects Proceedings of a joint IUFRO working party conference, February 6-11, 1994, Maui, Hawaii.

Morgan, R. E., De Groot, P. and Smith, S. M. 2004. Susceptibility of pine plantations to attack by the pine shoot beetle (Tomicus piniperda) in southern Ontario. Canadian Journal of Forest Research 34:2528-2540.

Scarr, T. 1998. Discussion session: Is this species a problem? Pages 36-43 in K. Ryall, S. M. Smith, eds. The pine shoot beetle in Ontario. Faculty of Forestry, University of Toronto, Toronto, Ontario.

USDA. 2016. Pine shoot beetle (Tomicus piniperda) North America quarantine area - PDF (1,467 kb). [Online] [2018].

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