Outrageous – Asian longhorned beetle Appears Again – Will US Respond Appropriately?

Here we go again … another Asian longhorned beetle population established in the U.S.

For the ninth time in 24 years, the Asian longhorned beetle (ALB) has been found in North America – this time in South Carolina.

This means thousands – perhaps tens of thousands – of trees will be removed. Thousands more will be injected with imadacloprid. Millions of dollars will be spent. There will be uncounted aesthetic and spiritual losses. There will be unmeasured damage to at least the local environment – which probably includes bottomland hardwood forests – protection of which South Carolina has declared to be a conservation priority. All this destruction is necessitated by the need to prevent catastrophic damage to North America’s hardwood forests by the ALB.

By early August I have learned that the South Carolina outbreak has been present for seven years or longer, and that it might be related to the Ohio outbreak (which was detected in 2011 but was probably introduced at least four years earlier). APHIS reports that, as of the end of July, nearly 1,300 infested trees had been detected. The area around the neighborhood where the detection was made is swampy – complicating search and removal operations and probably home to many box elder and willows – preferred hosts for the ALB.

Why did we let this happen? Why do we persist with a policy that has allowed repeated introductions of this pest via the well-documented wood packaging pathway? After all, we learned about this risk 22 years ago – after the ALB introductions to New York and Chicago. We have had plenty of evidence that the policy is failing. We know how to stop this. Why do we – through our elected and appointed government officials – not act to prevent it?

What We Need: a New, Protective Policy

With live pests continuing to be present in wood packaging 14 years after the U.S. and Canada imposed the treatment requirements in ISPM#15 – and 21 years after we required China to treat its wood packaging – we urgently need better federal policy. I have long advocated:

  • USDA APHIS join Bureau of Customs and Border Protection in penalizing violators for each violation; stop allowing five violations over a 12-month period before applying a penalty.
  • APHIS and the Canadian Food Inspection Agency (CFIA) should apply their rights under Section 5.7 of the World Trade Organization Sanitary and Phytosanitary Agreement to immediately prohibit China from packaging its exports in wood. China can use crates and pallets made from such alternative materials as plastic, metal, or oriented strand board.
  • APHIS and CFIA should being the process of supporting permanent application of this policy to China and other trade partners with poor compliance records. This step would require that they cite the need for setting a higher “level of protection” and then prepare a risk assessment to justify adopting more restrictive regulations.
  • USDA Foreign Agriculture Service (FAS) should assist U.S. importers to determine which suppliers reliably provide wood packaging that complies with ISPM#15 requirements.
  • USDA FAS and APHIS should help importers convey their complaints about specific shipments to the exporting countries’ National Plant Protection Organizations (NPPOs; departments of agriculture).
  • APHIS should increase pressure on foreign NPPOs and the International Plant Protection Convention more generally to ascertain the reasons ISPM#15 is failing and to fix the problems.
  • APHIS should fund more studies and audits of wood packaging to document the current efficacy of the standard, especially
    • Update the Haack study of pest approach rate.
    • Determine whether high rates of pest infestation of wood bearing the ISPM#15 mark results from fraud or failures of treatment – and whether any failures are due to mistakes/misapplication or shortcomings in the treatment themselves.
    • Allocate the risk among the three major types of wood packaging: pallets, crates, and dunnage. 

These folks work for us – tell them to protect our forests!

See also the recommendations of the Tree-Smart Trade program at www.tree-smart-trade.org

Tree-Smart also has a Twitter account: @treeSMARTtrade

Justification

The ALB poses a threat to 10% of US forests and nearly all of Canada’s hardwoods, so eradication of the South Carolina outbreak is essential. For a longer discussion of ALB introduction history, the threat, and eradication efforts to date, visit here. https://www.dontmovefirewood.org/pest_pathogen/asian-long-horned-beetle-html/).

Another ALB Outbreak in the US: No Surprise

This Chinese insect is a world traveler. It has been detected 36 times outside its natural range: in North America, Europe, and Japan. Seventeen of these outbreaks have been detected since 2012 (Eyre & Haack 2017). These 17 introduction have occurred six years or later after the 2006 implementation of the International Standard for Phytosanitary Measures (ISPM) #15 – which was intended to reduce the likelihood of such introductions. .Ten of the outbreaks have been eradicated (Eyre & Haack 2017; APHIS press release October 2019).  This includes four in the United States and Canada; see here.

Despite U.S. and international efforts, ALB and related pests have been detected continuously in imported goods. U.S. and European data (Eyre and Haack 2017) document rising numbers of Cerambycids detected in wood packaging in recent years. (For a description of pest prevention efforts, see Fading Forests II and III here and this blog).

It is also not surprising that the newly introduced pest is from China. It has long been among countries with the worst records on implementing ISPM#15

The APHIS-CBP joint study of pest interceptions over the period 2012 – 2017 (Krishnankutty et al. 2020b) found the highest numbers of interceptions came from Mexico, China, and Turkey. During the period 2011 – 2016, China accounted for 11% of interceptions (APHIS interception database – pers. comm. January 2017).

These numbers reflect in part the huge volumes of goods imported from China. But China’s poor performance has continued, perhaps even increased in recent years. For example, consider the choice of wood used to manufacture packaging. Authorities recognized by the late 1990s that wood from plantations of Populus from northern China was highly likely to be infested by the Asian longhorned beetle. Yet, more than a dozen years later, this high-risk wood was still being used: between 2012 and 2017, the ALB was intercepted six times in wood packaging made of Populus wood – each time originating from a single wood-treatment facility in China (Krishnankutty et al. 2020b).

The location just outside Charleston also is not a surprise. Charleston ranked seventh in receipt of incoming shipping containers in 2018. Charleston received 1,022,000 containers, or TEUs measured as 20-foot equivalents, in 2018 (DOT report). This was a 14% increase over the 894,000 TEUs in 2017 http://www.marad.dot.gov/MARAD_statistics/index.html – click on “trade statistics”, then “US Waterborne trade” (1st bullet).  I expect decreased import volumes in 2019 and 2020 due to the tariffs/trade war and the 2020 economic crash linked to the Covid-19 virus.

Why US and International Policy Still Fails

Leung et al. (2014) estimated that implementation of the International Standard of Phytosanitary Measures (ISPM)#15 resulted in only a 52% reduction in pest interceptions. They concluded that continued implementation at the 2009 level of efficacy could triple the number of wood borers established (not just intercepted) in the U.S. by 2050.

Since 2010 the Department of Homeland Security’s Bureau of Customs and Border Protection (CBP) has found an average of 794 shipments infested by pests each year (Harriger). In 2019 specifically, live pests were found in 747 shipments (Stephen Brady, CBP, April 2020). These violations were occurring four to 13 years after the U.S. began implementing ISPM#15 in 2006. According to my calculations, based on estimates of pest approach rates by Haack et al. (2014), these detections probably represented about eight percent of the total number of infested shipments entering the country each year.

And there are good reasons to think this estimate is low. First, Haack et al. (2014) did not include imports from China, Canada, or Mexico in their calculations. Both China and Mexico rank high among countries with poor compliance records. Second, Haack and Meissner based their calculations on 2009 data – 11 years out of date. Since 2009, ISPM#15 has been amended to make it more effective. The most important change was restricting the size of bark remnants that may remain on wood. Also, countries and trading companies have 11 more years of implementation – so they might have improved their performance. I have asked several times that APHIS commission a new analysis of Agriculture Quarantine Inspection Monitoring data. We all need an up-to-date determination of the pest approach rate, not only before but also after the CBP action. Without it, there’s no evidence whether the more aggressive enforcement stance CBP adopted in 2017 (see below) has led to reductions in non-compliant shipments at the border.

Another demonstration of the failure of ISPM#15 is the repeated presence of the velvet longhorned beetle (Trichoferus (=Hesperophanes) campestris) in wood packaging and its establishment in at least three states (Krishnankutty, et al. 2020a; also see the discussion in my recent blog here).

Astoundingly, data indicate that 97% of wood packaging infested with pests bears the stamp certifying that the wood has been treated according to the requirements of ISPM#15 – and hence should be pest-free (Eyre et al. 2018; CBP interception data). In other words, the presence of the stamp is not a reliable indicator of whether the wood has indeed been treated nor that it is pest-free. Scientists have speculated for years why this is the case. ALB’s new arrival provides an impetus to finally answer this question and to ensure policy reflects the answer.

What Federal Agencies Are Doing to Better Prevent Introductions

In contrast to such a comprehensive approach, this is what changes are under way.

CBP strengthened its enforcement in November 2017. The agency’s total “enforcement actions” increased by 400% from 2017 to 2018 (Sagle, pers. comm). The 2019 data show decreases, in absolute numbers, from earlier years in all categories: a 19% decrease below 2010-2018 in average number of shipments intercepted; a 13% decrease in number of shipments intercepted because the wood packaging lacked the ISPM#15 mark; and a decrease of 6% in the number of shipments intercepted that had a quarantine pest (Stephen Brady, CBP, April 2020). However, one year of interception data do not provide a basis for saying whether CBP’s stronger enforcement has resulted in a lower number of shipments in violation of ISPM#15 approaching our shores. Again, I call for APHIS to repeat Haack et al. (2014) study.

Harriger reported that CBP is also trying harder to educate importers, trade brokers, affiliated associations, CBP employees, and international partners about ISPM#15 requirements. CBP wants to encourage them to take actions to reduce all types of non-compliance: lack of documentation, pest presence in both wood packaging and shipping containers, etc.

APHIS has not altered its long-standing policy of allowing an importer to rack up five violations over a 12-month period before imposing a penalty. Instead, APHIS has focused on “educating” trade partners to encourage better compliance. For example, APHIS worked with Canada and Mexico – through the North American Plant Protection Organization — to sponsor workshops for agricultural agencies and exporters in Asia and the Americas

APHIS also planned to host international symposia on wood packaging issues as part of events recognizing 2020 as the International Year of Plant Health. These symposia have been postponed by travel and other restrictions arising from the coronavirus pandemic.

The Broader Significance of Continuing Wood Packaging Problems

The premise of the international phytosanitary system – the Agreement on the Application of Sanitary and Phytosanitary Standards (SPS Agreement) and the International Plant Protection Convention (IPPC) – is that importing countries should rely on exporting countries to take the actions necessary to meet the importing countries’ plant health goals. The ISPM#15 experience undermines the very premise of these international agreements.

If we cannot clean up the wood packaging pathway – which involves boards or logs that are, after all, already dead – it bodes poorly for limiting pests imported with other commodities that are pathways for tree-killing pests – especially living plants (plants for planting). Living plants are much more easily damaged or killed by phytosanitary measures, so ensuring pest-free status of a shipment is even more difficult.  (A longer discussion of the SPS Agreement and IPPC is found in Chapter III of Fading Forests II, available here.

SOURCES

Eyre, D., R. Macarthur, R.A. Haack, Y. Lu, and H. Krehan. 2018. Variation in Inspection Efficacy by Member States of SWPM Entering EU. Journal of Economic Entomology, 111(2), 2018, 707–715)

Haack RA, Britton KO, Brockerhoff EG, Cavey JF, Garrett LJ, et al. (2014) Effectiveness of the International Phytosanitary Standard ISPM No. 15 on Reducing Wood Borer Infestation Rates in Wood Packaging Material Entering the US. PLoS ONE 9(5): e96611.

Kevin Harriger, US CBP. Presentations to the annual meetings of the Continental Dialogue on Non-Native Forest Insects and Diseases over appropriate years. See, e.g., https://continentalforestdialogue.org/continental-dialogue-meeting-november-2018/

Krishnankutty, S.M., K. Bigsby, J. Hastings, Y. Takeuchi, Y. Wu, S.W. Lingafelter, H. Nadel, S.W. Myers, and A.M. Ray. 2020a. Predicting Establishment Potential of an Invasive Wood-Boring Beetle, Trichoferus campestris (Coleoptera:) in the United States. Annals of the Entomological Society of America, XX(X), 2020, 1–12

Krishnankutty,  S., H. Nadel, A.M. Taylor, M.C. Wiemann, Y. Wu, S.W. Lingafelter, S.W. Myers, and A.M. Ray. 2020b. Identification of Tree Genera Used in the Construction of Solid Wood-Packaging Materials That Arrived at U.S. Ports Infested With Live Wood-Boring Insects. Commodity Treatment and Quarantine Entomology

Leung, B., M.R. Springborn, J.A. Turner, E.G. Brockerhoff. 2014. Pathway-level risk analysis: the net present value of an invasive species policy in the US. The Ecological Society of America. Frontiers of Ecology.org

Meissner, H., A. Lemay, C. Bertone, K. Schwartzburg, L. Ferguson, L. Newton. 2009. Evaluation of Pathways for Exotic Plant Pest Movement into and within the Greater Caribbean Region. Caribbean Invasive Species Working Group (CISWG) and USDA APHIS Plant Epidemiology and Risk Analysis Laboratory

USDA APHIS interception database – pers. comm. January 2017.

USDA APHIS press release dated September 12, 2018

U.S. Department of Agriculture, Press Release No. 0133.20, January 27, 2020

U.S. Department of Transportation, Maritime Administration, U.S. Waterborne Foreign Container Trade by U.S. Customs Ports (2000 – 2017) Imports in Twenty-Foot Equivalent Units (TEUs) – Loaded Containers Only at https://ops.fhwa.dot.gov/freight/freight_analysis/nat_freight_stats/docs/06factsfigures/fig2_9.htm and

US Department of Transportation. Port Performance Freight Statistics in 2018 Annual Report to Congress 2019  https://rosap.ntl.bts.gov/view/dot/43525

Posted by Faith Campbell

We welcome comments that supplement or correct factual information, suggest new approaches, or promote thoughtful consideration. We post comments that disagree with us — but not those we judge to be not civil or inflammatory.

Unique Black Ash Wetlands – Threatened by Emerald Ash Borer

Another unique ecosystem being severely damaged by non-native tree-killing pests are the wetlands dominated by black ash (Fraxinus nigra). Black ash typically grows in fens, along streams, or in poorly drained areas that often are seasonally flooded. Such swamps stretch from Minnesota to Newfoundland; in the three states of Michigan, Wisconsin, and Minnesota, they cover a total of over 2 million hectares (Kolka et al. 2018).

locations of black ash swamps; source

Recent research allows us to understand the impending loss to these unique ecosystems that will be caused by the emerald ash borer (EAB).

Hydrology is the dominant factor that influences a host of ecosystem functions in black ash wetlands. Water levels are largely determined by a combination of precipitation and evapotranspiration rates. Black ash can thrive in wetter areas than most other tree species (Slesak et al. 2014). Water tables in these swamps are typically above the surface throughout early spring, followed by drawdown below the surface during the growing season with periodic rises following rain events. Water table drawdown coincides with peak evapotranspiration following black ash leaf out, demonstrating the fundamental control that this species has on animal and other plant communities (Kolka et al. 2018; Slesak et al. 2014).

Ecological Importance

Black ash generally dominate the canopy of these wetlands. Ash density can range from about 40% to almost 100%. Several other tree species are present, including northern white cedar (Thuja occidentalis), red maple (Acer rubrum), American elm (Ulmus americana) (Kolka et al. 2018), quaking aspen (Populus tremuloides), American basswood (Tilia americana), and bur oak (Quercus macrocarpa) (Slesak et al. 2014), balsam fir (Abies balsamea), balsam poplar (Populus balsamifera), and speckled alder (Alnus incana) (Youngquist et al. 2020). Black ash, by maintaining low water levels during the growing season, creates conditions under which these other trees can live but not thrive (summary of study by B.J. Palik, USDA Forest Service, here. Most other species lack  the  physiological adaptations of black ash or face pathogenic constraints (e.g., Dutch elm disease on American elm Ulmus americana) (Kolka et al. 2018).

Ash trees in these swamps are uneven-aged with canopy tree ages ranging from 130–232 years (Slesak et al. 2014). This complexity provides important habitat for many wildlife species, including ground beetle community assemblages (Kolka et al. 2018) and an abundance of aquatic macroinvertebrates. These are characterized and dominated by mollusks (Sphaeriidae, Lymnaeidae, Physidae), annelids (Lumbriculidae, Hirudinea), caddisflies (Limnephilidae, Leptoceridae), and dipterans (Chironomidae, Culicidae) (Youngquist et al. 2020).

a black ash swamp; source: Flickr

A major concern is that loss of trees – especially ash – might result in open marshes dominated by grasses, especially lake sedge (Carex lacustris). Conversion to sedge-dominated marshes has been observed in areas where trees have been removed as part of experiments to test various ecosystem responses to loss of the ash component (Slesak et al. 2014). Even if other trees took the place of ash, the substitutes might not support the same animal communities (see below).

Impact of Emerald ash borer and loss of black ash

Black ash is highly susceptibility to the EAB (Engelken and McCullough, 2020), so scientists expect severe impacts of the invasion in ash-dominated wetlands and – to a somewhat lesser extent — in forested stream systems’ riparian areas (Engelken and McCullough, 2020). They expect cascading impacts on 1) hydrology; 2) plant communities; 3) wildlife; 4) Native American cultures; and possibly even storage of carbon in vegetation and soils (Kolka et al. 2018).

            1) Hydrology

Experiments suggest that loss of ash will cause higher water tables, especially during late summer and fall (Kolka et al 2018). This will result from reductions in evapotranspiration as large trees are replaced by shrubs and grasses (see below) (Kolka et al. 2018; Slesak et al. 2014). The higher water table might be exacerbated if higher annual precipitation levels predicted by climate change models occur. On the other hand, these models also predict a simultaneous increase in longer droughts, which might partially counteract higher precipitation and reduced evapotranspiration (Kolka et al. 2018). If they occur, these possible increases in drought length and frequency might enhance the establishment of less water-tolerant non-ash tree species in former black ash wetlands.

            2) Plant Communities

Higher water tables are expected to reduce tree densities and promote conversion to open or shrub-dominated marshes. Several of the possible alternative tree species do not thrive as well as black ash under current conditions (Kolka et al. 2018). However, new hydrologic conditions might make forest restoration even more difficult because herbaceous plants transpire less water than trees, thus exacerbating the rising water tables (Slesak et al. 2014).

In upper Michigan, experiments which killed ash by cutting or girdling did not lead to an increase in growth rates of the remaining canopy species despite the increase in available resources (e.g., sunlight and nutrients) – presumably because of the raised water table (Kolka et al. 2081).

While some studies have found that black ash seedlings and saplings dominated the woody component of the swamp understory up to three years after ash were experimentally removed (Kolka et al. 2018), Engelken and McCullough (2020) found only eight saplings and a single seedling.

Scientists have planted several tree species in experiments to see which might be used to maintain the forested wetlands in the absence of black ash. The results are a confusing mix. Some species grew well once established – but had low levels of seedling establishment. Some trees planted on elevated microsites (hummocks) had the greatest survival and growth rates. (For specific data, see Kolka et al. 2018). A further consideration is tree species’ ability to adapt to warming temperatures already evident and expected to increase in coming decades (Slesak et al. 2014).

Consequently, Slesak et al. (2014) think it is likely that the EAB invasion will alter vegetation dynamics and cause a shift to an altered ecosystem state (e.g., open marsh condition) with higher water tables. They caution that the degree of ecosystem alteration will vary depending on site hydrology, annual precipitation, and period of time necessary for establishment of deeper rooted vegetation.

            3) Wildlife

Moreover, any changes in vegetation will also affect the biota in more subtle ways through altered nutrient cycles. Black ash leaf litter is highly nutritious, having some of the highest nitrogen, phosphorus, and cation contents of any hardwood forest species (Kolka et al. 2018). Black ash leaves also decompose faster than most alternative tree species’ leaves (summary of Palik USDA Forest Service, here;  Youngquist et al. 2018).

Youngquist et al. (2018) studied litter breakdown, litter nutritional quality, and growth of a representative invertebrate litter feeder – larvae of a shredding caddisfly (Limnephilus indivisus). They found that the larvae’s risk of death increased by a factor of three times or more when caddisflies were fed American elm, balsam poplar, or lake sedge leaves compared to black ash leaf litter. Even when the larvae lived – but matured more slowly because of the lower nutrition value of the leaves – they would still be vulnerable because they must reach metamorphosis before pond dry-down. In any planting done to maintain forested quality of wetlands, need to consider the nutritional quality of the leaf litter provided by replacements. Speckled alder was only apparently acceptable substitute; it was second to black ash in acceptability to caddisflies (Youngquist et al. 2020)

In fact, Youngquist et al. (2020) concluded that plant and detritivore biodiversity loss due to EAB invasion could alter productivity and decomposition at rates comparable to other anthropogenic stressors (e.g., climate change, nutrient pollution, acidification). The result will be altered biogeochemical cycles, resource availability, and plant and animal communities.

Scientists are also concerned about the impact of ash tree mortality on forest connectivity. Conversion of wooded swamps to shrub-and sedge-dominated wetlands will result in the loss of important micro-habitats that are already limited across the forested landscape and may also reduce availability of critical habitat for migrating birds. These changes will exacerbate on-going changes in land use in the Great Lakes region that are causing loss of forest habitat and forest homogenization. As yet, the magnitude of the impact on wildlife is unclear (Kolka et al. 2018).

black ash baskets – displayed at 2006 conference
photo by Faith Campbell

            4) Cultural importance – baskets

Native Americans living in the range of black ash have utilized the wood to make baskets and other tools for thousands of years. Baskets had numerous uses, such as packs for carrying items, fish traps, and for preparing food and storing household items. Ash items also had ceremonial uses and they are highly sought as gifts and in trade. The skill needed to select a good tree and work the wood is handed down through the generations and is an important part of tribes’ culture (Benedict 2010).

Discussion of these cultural traditions can be found as Powerpoints here and here.

A video is posted here.

USFS Research Efforts

Concerned by the spread of EAB and probable impact on black ash swamps, the USDA Forest Service has initiated major research studies with the goal of filling in the numerous knowledge gaps and developing management recommendations. A large-scale study using various manipulations to simulate the EAB invasion was initiated in the Chippewa National Forest in northern Minnesota in 2009. A companion study began in the Ottawa National Forest in Michigan in 2010 (Kolka et al. 2018). The Slesak, Youngquist, and Kolka publications cited in this blog report results of some of the studies in this project. Other studies of black ash conditions, including regeneration, at various stages of the EAB invasion wave are being carried out by Deb McCullough, Nate Siegert, and others. They are working at sites from Michigan to New England (D.G. McCullough, pers. comm.).

Posted by Faith Campbell

We welcome comments that supplement or correct factual information, suggest new approaches, or promote thoughtful consideration. We post comments that disagree with us — but not those we judge to be not civil or inflammatory.

For a detailed discussion of the policies and practices that have allowed these pests to enter and spread – and that do not promote effective restoration strategies – review the Fading Forests report here.

For a great discussion of black ash basketweavers,  see Anne Bolen, A Silent Killer: Black Ash Basket Makers are Battling a Voracious Beetle to Keep their Heritage Alive, American Indian Magazine,  Spring  2020, available here. 

SOURCES

Benedict, M. 2010. Ecology and the Cultural and Economic Importance of Black ash (Fraxinus nigra Marsh) for Native Americans May 2010 https://www.fs.usda.gov/Internet/FSE_DOCUMENTS/stelprdb5191796.pdf

Engelken, P.J. and D.G McCullough. 2020. Riparian Forest Conditions Along Three Northern Michigan Rivers Following Emerald Ash Borer Invasion. Canadian Journal of Forest Research. Submitted

Kolka, R.K., A.W. D’Amato, J.W. Wagenbrenner, R.A. Slesak, T.G. Pypker, M.B. Youngquist, A.R. Grinde and B.J. Palik. 2018. Review of Ecosystem Level Impacts of Emerald Ash Borer on Black Ash Wetlands: What Does the Future Hold? Forests 2018, 9, 179; doi:10.3390/f9040179 www.mdpi.com/journal/forests

Slesak, R.A., C.F. Lenhart, K.N. Brooks, A.W. D’Amato, and B.J. Palik. 2014. Water table response to harvesting and simulated emerald ash borer mortality in black ash wetlands in MN, USA. Can. J. Forestry. Res. 44:961-968.

Youngquist, M.B., C. Wiley, S.L. Eggert, A.W. D’Amato, B.J. Palik, & R.A. Slesak. 2020. Foundation Species Loss Affects Leaf Breakdown and Aquatic Invertebrate Resource Use in Black Ash Wetlands. Wetlands. Society of Wetland Scientists

Posted by Faith Campbell

We welcome comments that supplement or correct factual information, suggest new approaches, or promote thoughtful consideration. We post comments that disagree with us — but not those we judge to be not civil or inflammatory.

For a detailed discussion of the policies and practices that have allowed these pests to enter and spread – and that do not promote effective restoration strategies – review the Fading Forests report at http://treeimprovement.utk.edu/FadingForests.htm

International Year of Plant Health: Time to Admit that the International Phytosanitary System is Failing

As I noted last November, the premise of the international phytosanitary system – the Agreement on the Application of Sanitary and Phytosanitary Standards (SPS Agreement) and the International Plant Protection Convention (IPPC) – is that importing countries should, and can, rely on exporting countries to take the actions necessary to meet the importing countries’ plant health goals. However, the experience with the International Standard on Phytosanitary Measures (ISPM) #15 and wood packaging casts doubt on this premise.

Exporters are not reliably ensuring the cleanliness of their wood packaging, putting American forests at risk. Indeed, some experts have concluded that continuing to implement ISPM#15 at current levels could triple the number of non-native wood-boring insects introduced into the U.S. by 2050 (Leung et al. 2014).

Too many shipments carry wood packaging that bears no ISPM#15 stamp. And too many pieces of wood packaging arrive with the ISPM#15 stamp, yet are not reliably pest-free. If we cannot clean up this pathway – which involves boards or even logs that are, after all, already dead — it bodes poorly for limiting pests imported with other commodities that are pathways for tree-killing pests – especially living plants (plants for planting). Living plants are much more easily damaged or killed by treatments than the dead wood used in packaging – so ensuring pest-free status of a shipment is even more difficult.  (A longer discussion of the SPS Agreement and IPPC is found in Chapter III of Fading Forests II, available here.

Here are the problems – and the latest evidence.

ALB larva in piece of wood packaging material

Too Many Shipments with Pest-Infested Wood Packaging Are Reaching the Country

My information on Customs and Border Protection (CBP) interceptions comes primarily from Kevin Harriger (see full reference at end of the blog). I will note when it comes from other sources.

In November 2019, Kevin Harriger reported that over the past three years, CBP detected a regulated pest, on average, in 30% of the wood packaging the agency intercepted because it was not compliant with ISPM#15. Non-compliance is defined as wood packaging that either lacks an official mark or is infested by a quarantine pest, or both.

From this and previous reports, I have 10 years of CBP interception data – from 2020 – 2019. These data thus begin four years after the U.S. began implementing ISPM#15 (in 2006) and 11 years after the U.S. began requiring China to treat wood packaging accompanying its exports (in 1999).

Over the period 2010 – 2018, CBP intercepted an average of 3,183 shipments with non-compliant wood packaging each year. On average, 2,100 (66%) of these shipments lacked the required ISPM#15 mark. A live quarantine pest was found in an average of 794 (25%) shipments. (There was some overlap in the categories).

In 2019, CBP intercepted a total of 2,572 non-compliant shipments (Stephen Brady, CBP, April 2020). Those lacking the ISPM#15 mark number 1,825 (71%). Shipments in which a live pest was found numbered 747 (29%).

The 2019 data show decreases, in absolute numbers, from earlier years in all categories: a 19% decrease below 1010-2018 average of shipments intercepted; a 13% decrease in number of shipments intercepted because the wood packaging lacked the ISPM#15 mark; a decrease of 6% in the number of shipments intercepted that had a quarantine pest. It is too early to say whether CBP’s stronger enforcement approach launched in November 2017 has resulted in a lower number of shipments in violation of ISPM#15 approaching our shores.

There has been a dispute about which categories of packaging are most likely to be infested. The categories are pallets, crates, spools for cable, and dunnage (wood used to brace cargo and prevent it from shifting). The CBP data available to me and the study by Krishnankutty et al. (2020b – see full reference at the end of this blog) shed no light on that issue.  

What is the actual number of infested containers approaching our shores? We know that CBP inspects, on average, 2% of incoming containers – so the above interception data reflect a small percentage of probable true approach rate.

The first issue is, how many containers arrive here?

I have been unable to find data for 2019 – much less 2020, when the media report that import volumes have crashed. Until recently, import volumes had been rising. According to a U.S. DOT report to Congress (see reference at the end of this blog), 25 U.S. maritime ports received 24,789,000 loaded shipping containers (measured as TEU – 20-foot equivalent) in 2018. The number of incoming containers had increased at the top three ports – Long Beach, Los Angeles, and New York / New Jersey – between 3% and 7% since 2016.

However, APHIS told me in November 2019 that CBP reports that only about 13 million loaded containers enter the country every year by rail, truck, air, or sea. While I can’t yet explain the discrepancy, one possible explanation is that DoT counts 40-foot containers as two 20-foot containers.

(Of course, pests introduced to Canada also threaten North America’s forests. Canada received fewer than 5 million containers via maritime trade in 2016 (Asbil pers. comm. 2018).

Two decade-old estimates of the proportion of incoming containers that hold wood packaging (Haack et al. 2017, Meissner et al. 2009) allow me to estimate the risk associated with these incoming containers. Meissner et al. found that 75% of maritime containers have wood packaging. Haack et al. estimated that the wood in 0.1% of those containers was infested. Applying these two factors, I conclude that as many as 18,590 of incoming containers in maritime trade could have been transporting a woodborer in the regulated families (Cerambycids, Buprestids, Siricids). I am hesitant to apply the calculation to CBP’s estimate because I don’t know how many of the 13 million containers entered by sea. However, if I assume that the same percentage of wood packaging applied to all the CBP-counted containers, I conclude that 9,750 of those containers held infested wood packaging – still a significant number.

The actual approach rate might be less – or more! Haack et al. (2014) did not include imports from China in their calculations. Given the history of interceptions, it appears probable to me that a recalculation of the approach rate that included China would probably raise the overall proportion.

Furthermore, 11 years have passed since Haack and Meissner made their calculations. During that time, ISPM#15 has been amended to make it more effective. The most important change was restricting the size of bark remnants that may remain on the wood. I have asked several times that APHIS commission a new analysis of Agriculture Quarantine Inspection Monitoring data to determine the pest approach rate before and after the CBP action in order to determine whether the more aggressive enforcement has led to reductions in non-compliant shipments at the border.

By comparing Dr. Haack’s estimate (see above) with the CBP data, I estimate that Customs is detecting and halting the importation of 4 – 8% of the shipments that actually contain pest-infested wood. Since CBP inspects only about two percent of incoming shipments, the higher detection rate demonstrates the value of CBP’s program to target likely violators – and deserves praise. But it is obviously too low a “catch” rate to provide an adequate level of protection for our forests. 

ISPS#15 Is Not Helping to Target Inspections

So – ISPM#15 still allows too many pests to arrive at our shores. Is ISPM#15 at least helping phytosanitary agencies target inspections? No, because both U.S. and European data demonstrate that a high proportion of shipments containing infested wood pieces bore the ISPM#15 stamp. Phytosanitary agencies cannot rely on the presence or absence of the stamp to indicate the pest risk level.

U.S. data:

  • During the period 2010-2015, CBP found that an average of 95% of pest-infested shipments bore the ISPM#15 mark (Harriger). Unfortunately, CBP data from more recent years don’t provide this breakdown.
  • In the past two years, CBP inspectors have repeatedly found pests in dunnage bearing the ISPM#15 mark.
  • Krishnankutty et al. (2020b) analyzed wood packaging from 42 countries of origin intercepted by CBP over six years (April 2012 – January 2018). They found that 87% of the interceptions bore the ISPM mark.

I blogged earlier about the velvet longhorned beetle (Trichoferus (=Hesperophanes) campestris) This pest, like others, has reached our shores and entered the country both before and after implementation of ISPM#15. The predictable result is that VLB is established in three states and has been detected in 14 others plus Puerto Rico (Krishnankutty, et al. 2020a). Apparently we have been lucky that this one isn’t as damaging as so many are!

European data:

For Europe, see Eyre et al. (2018). They concluded that the ISPM-15 mark was of little value in predicting whether harmful organisms were present.

This is alarming and we need to understand the reason – How much is caused by fraud? How much is caused by failure of treatment – either intrinsic weakness or incorrect application? APHIS researchers have found that larvae from wood subjected to methyl bromide fumigationwere more likely to survive to adulthood than those intercepted in wood that had been heat treated (Nadel et al. 2016).

Krishnankutty et al. (2020b) query whether the 2009 requirement that wood be debarked might be less effective in countering insect species that require bark only in the early stages of larval development. Half of the species intercepted in hardwood shipments (e.g., Anoplophora glabripennis, Phoracantha recurva) might fit this profile. They also appear to pose a higher threat since they are polyphagous and known to infest healthy hosts. While some of the softwood-inhabiting species also require bark, they not known to infest living trees and only a quarter were classified in the high-risk group. The Mech et al. 2020 finding that no wood-borers that specialize in conifers posed a high risk appears to support these different impacts.

Krishnankutty, et al. (2020b) also note the risk from pallet recycling. The wood might occasionally be infested by dry-wood borers. One puzzling example was wood packaging shipped from Brazil and bearing a Brazilian ISPM#15 stamp that was infested with a larva of T. campestris (VLB). This is an Asian species not recorded as being present in South or Central America. The authors speculate that the pallets were recycled in Brazil after inadequate treatment in their original places of manufacture.

Of the 17 wood borer species intercepted in hardwoods, three have reproducing populations in the U.S.: A. glabripennis, Phoracantha recurva and T. campestris. Krishnankutty et al. (2020b) say that they are unaware of any of the non-native buprestids and siricids intercepted in softwood SWPM being established in the US. (One Siricid that is established, Sirex noctillio, was not detected in the wood packaging analyzed in this study.)

What Can Be Done to Slow or Eliminate this Pathway?

CBP inspectors

CBP strengthened enforcement of ISPM#15 in November 2017. CBP’s enforcement actions increased by 400% from 2017 to 2018 (John Sagle, CBP, pers. comm). CBP has also expanded its outreach to shippers and others involved in international trade with the goal of reducing all types of non-compliance – lack of documentation, pest presence, etc. in both wood packaging and shipping containers. The outreach includes awareness campaigns targetting trade, industry, affiliated associations, CBP employees, and international partners (Harriger).

Certain countries have a long-standing record of non-compliance with ISPM#15 – as seen in interception records.

  • Haack et al. 2014 – Italy was the country of origin for most wood borers intercepted 1985 – 2000.
  • Haack et al. 2014 – the top 5 countries in the 2003 – 2009 period were Mexico (33.7%), Italy (14.2%), Canada (13.4%), Netherlands (4.4%), China (4.1%).
  • APHIS’ interception database for FY2011-2016 (provided to me) showed Mexico, China, Italy, and Costa Rica had the highest numbers of interceptions.
  • Krishnankutty et al. (2020b) found the highest numbers of interceptions came from Mexico, China, and Turkey.

These numbers reflect in part the huge volumes of goods imported from both Mexico and China. But China and Italy stand out for their poor performance. (The U.S. does not regulate – or inspect! – wood packaging from our third-largest trade partner Canada.)

Officials know which individual companies within these countries have a history of non-compliance. For example, 21 of the interceptions on wood packaging made from Populus trees in China (53%) were associated with stone, ceramic, and terracotta commodities. Anoplophora glabripennis was intercepted six times in Populus originating from a single wood-treatment facility in China (Krishnankutty et al. 2020b).

How reduce risk to U.S. forests?

Over the past year or two, I have suggested the following actions:

  1. USDA APHIS join Bureau of Customs and Border Protection in penalizing violators.
  2. Citing the need for setting a higher “level of protection”, APHIS & the Canadian Food Inspection Agency (CFIA) should prepare a risk assessment to justify adopting more restrictive regulations. The new regulations should prohibit use of packaging made from solid wood – at least from the countries with records of high levels of non-compliance (listed above).
  3. USDA Foreign Agriculture Service (FAS) should assist U.S. importers to determine which suppliers reliably provide compliant wood packaging.
  4.  USDA FAS and APHIS should help importers convey their complaints about specific shipments to the exporting countries’ National Plant Protection Organizations (NPPOs; departments of agriculture).
  5. APHIS should increase pressure on foreign NPPOs and the International Plant Protection Convention more generally to ascertain the reasons ISPM#15 is failing and to fix the problems.
  6. APHIS should fund more studies and audits of wood packaging to document the current efficacy of the standard, including an urgent update of the Haack study of pest approach rate.

The international standard has demonstrably failed to provide a secure method to evaluate the pest risk associated with wood packaging accompanying any particular shipment. The presence of the stamp on pieces of wood packaging does not reliably show that the wood is pest-free.

The situation is even worse re: movement of plants for planting.

SOURCES

Asbil, W. Canadian Food Inspection Agency, pers. comm. August 2018.

Eyre, D., R. Macarthur, R.A. Haack, Y. Lu, and H. Krehan. 2018. Variation in Inspection Efficacy by Member States of SWPM Entering EU. Journal of Economic Entomology, 111(2), 2018, 707–715)

Haack, R. A., K. O. Britton, E. G. Brockerhoff, J. F. Cavey, L. J. Garrett, M. Kimberley, F. Lowenstein, A. Nuding, L. J. Olson, J. Turner, and K. N. Vasilaky. 2014. Effectiveness of the international phytosanitary standard ISPM no. 15 on reducing wood borer infestation rates in wood packaging material entering the United States. Plos One 9:e96611.

Harriger, K. Executive Director for the Agriculture Programs and Trade Liaison office, Department of Homeland Security Bureau of Customs and Border Protection (CBP), presentations to the Continental Dialogue on Non-Native Forest Insects and Diseases, over appropriate years. https://continentalforestdialogue.org/events/

Krishnankutty, S.M., K. Bigsby, J. Hastings, Y. Takeuchi, Y. Wu, S.W. Lingafelter, H. Nadel, S.W. Myers, and A.M. Ray. 2020a. Predicting Establishment Potential of an Invasive Wood-Boring Beetle, Trichoferus campestris (Coleoptera:) in the United States. Annals of the Entomological Society of America, XX(X), 2020, 1–12

Krishnankutty,  S., H. Nadel, A.M. Taylor, M.C. Wiemann, Y. Wu, S.W. Lingafelter, S.W. Myers, and A.M. Ray. 2020b. Identification of Tree Genera Used in the Construction of Solid Wood-Packaging Materials That Arrived at U.S. Ports Infested With Live Wood-Boring Insects. Commodity Treatment and Quarantine Entomology

Leung, B., M.R. Springborn, J.A. Turner, E.G. Brockerhoff. 2014. Pathway-level risk analysis: the net present value of an invasive species policy in the US. The Ecological Society of America. Frontiers of Ecology.org

Mech,  A.M., K.A. Thomas, T.D. Marsico, D.A. Herms, C.R. Allen, M.P. Ayres, K.J. K. Gandhi, J. Gurevitch, N.P. Havill, R.A. Hufbauer, A.M. Liebhold, K.F. Raffa, A.N. Schulz, D.R. Uden, & P.C. Tobin. 2019. Evolutionary history predicts high-impact invasions by herbivorous insects. Ecol Evol. 2019 Nov; 9(21): 12216–12230.

Meissner, H., A. Lemay, C. Bertone, K. Schwartzburg, L. Ferguson, L. Newton. 2009. Evaluation of Pathways for Exotic Plant Pest Movement into and within the Greater Caribbean Region. Caribbean Invasive Species Working Group (CISWG) and USDA APHIS Plant Epidemiology and Risk Analysis Laboratory

Nadel, H. S. Meyers, J. Molongoski, Y. Wu, S. Lingafelter, A. Ray, S. Krishnankutty, A. Taylor. 2017. Identification of Port Interceptions in Wood Packing Material Cumulative Progress Report, April 2012 – June 2017

USDA APHIS interception database – pers. comm. January 2017.

USDA APHIS press release dated September 12, 2018

U.S. Department of Agriculture, Press Release No. 0133.20, January 27, 2020

US Department of Transportation. Port Performance Freight Statistics in 2018 Annual Report to Congress 2019 https://rosap.ntl.bts.gov/view/dot/43525

Wu, Y., S.M. Krishnankutty, K.A. Vieira, B. Wang. 2020. Invasion of Trichoferus campestris (Coleoptera: Cerambycidae) into the United States characterized by high levels of genetic diversity and recurrent intros. Biological Invasions Volume 22, pages1309–1323(2020)

Yemshanov, D., F.H. Koch, M. Ducey, K. Koehler. 2012. Trade-associated pathways of alien forest insect entries in Canada. Biol Invasions (2012) 14:797–812

Posted by Faith Campbell

We welcome comments that supplement or correct factual information, suggest new approaches, or promote thoughtful consideration. We post comments that disagree with us — but not those we judge to be not civil or inflammatory.

Non-Native Pests on North American Conifers: New Overview

Fraser fir killed by balsam woolly adeligid
Clingman’s Dome, Tennessee

A recent study provides an overview of the threat non-native insects pose to conifers in North America. Unfortunately, pathogens are not included in the study. I provide a citation to the study (Mech et al., 2019) at the end of this blog.

The study’s authors based their analysis on 58 insects that specialize on conifers (trees in the families Cupressaceae, Pinaceae, and/or Taxaceae). These were derived from a list of over 500 herbivorous insects identified by Aukema et al. (2010) and Yamanaka et al.  (2015). Mech and colleagues determined that of the approximately 100 conifer species native to North America, 49 have been colonized by one or more of these 58 non-native insects. Three-quarters of the affected trees have been attacked by more than one non-native insect. One tree species was attacked by 21 non-native insects.

Looked at from the opposite perspective, one of the insects attacked 16 novel North American hosts.

Of these 58 insects, only six are causing high impacts, all in the orders Hymenoptera (i.e., sawflies) and Hemiptera (i.e., adelgids, aphids, and scales). (“High impact” is defined as causing mortality in the  localized host population, recognizing potential spread.)

These six are (1) Adelges piceae—balsam woolly adelgid; (2) Adelges tsugae—hemlock woolly adelgid; (3) Elatobium abietinum—green spruce aphid; (4) Gilpinia hercyniae—European spruce sawfly; (5) Matsucoccus matsumurae—red pine scale; and (6) Pristiphora erichsonii—larch sawfly. The high-impact pests included no wood borers, root feeders, or gall makers.

Mech and colleagues analyzed these relationships in an effort to determine factors driving bioinvaders’ impacts. They evaluated the probability of a non-native conifer specialist insect causing high impact on a novel North American host as a function of the following: (a) evolutionary divergence time between native and novel hosts; (b) life history traits of the novel host; (c) evolutionary relationship of the non-native insect to native insects that have coevolved with the shared North American host; and/or (d) the life history traits of the non-native insect.

They found that the major drivers of impact severity for those that feed on foliage and sap  (remember, they did not evaluate other feeding guilds) were:

1) Host’s evolutionary history – Divergence time in millions of years (mya) since North American species diverged from a coevolved host of the insect in its native range. The greatest probability of high impact for a leaf-feeding specialist was on a novel conifer that diverged from the native conifer host recently (~1.5–5 mya). The divergence time for peak impact was longer for sap‐feeders (~12–17 mya). The predictive power of the divergence-time factor was stronger for sap-feeders than for leaf feeders.

2) Shade tolerance and drought intolerance – A tree species with greater shade tolerance and lower drought tolerance is more vulnerable to severe impacts. This profile fits most species of Abies, Picea, and Tsuga. On the other hand, novel hosts with low shade tolerance and higher drought tolerance had a very low likelihood of suffering severe impacts.

a bad infestation of hemlock woolly adelgid

3) Insect evolutionary history – When a non-native insect shares a host with a closely related herbivore native to North America, the invader is less likely to cause severe impacts. However, this factor in isolation had relatively poor predictive performance.

None of the insect life history traits examined, singly or in combination, had predictive value. The traits evaluated were feeding guild, native region, pest status in native range, number of native host genera, voltinism (frequency of egg-laying periods), reproductive strategy, fecundity, and/or mechanism of dispersal.

See Mech et al. (2019) for a discussion of hypotheses that might explain these findings.

My Questions Answered!

The authors inform me that their project will eventually include introduced insects attacking all kinds of trees. The more than 500 insect species that utilize woody hosts have been placed into one of three categories: 1) conifer specialist (only utilizes conifer hosts), 2) hardwood/woody angiosperm specialist (only utilizes hosts in a single angiosperm family), or 3) generalists (utilizes hosts in more than one angiosperm family or both angiosperms and conifers) (Mech pers. comm.) They began with the smallest group – the conifer specialists – so that they could more easily work out kinks in their procedures.

I had asked why the brown spruce longhorned beetle (Tetropium fuscum) – which is established in Nova Scotia – was not included in this study. According to the authors, this cerambycid beetle has been reported to feed occasionally on hardwood species, so it has been placed in the third group.noted above.

SOURCES

Aukema, J.E., D.G. McCullough, B. Von Holle, A.M. Liebhold, K. Britton, & S.J. Frankel. 2010. Historical Accumulation of Nonindigenous Forest Pests in the Continental United States. Bioscience. December 2010 / Vol. 60 No. 11

Mech,  A.M., K.A. Thomas, T.D. Marsico, D.A. Herms, C.R. Allen, M.P. Ayres, K.J. K. Gandhi, J. Gurevitch, N.P. Havill, R.A. Hufbauer, A.M. Liebhold, K.F. Raffa, A.N. Schulz, D.R. Uden, & P.C. Tobin. 2019.  Evolutionary history predicts high-impact invasions by herbivorous insects. Ecol Evol. 2019 Nov; 9(21): 12216–12230.

Yamanaka, T., Morimoto, N. , Nishida, G. M. , Kiritani, K. , Moriya, S. , & Liebhold, A. M. (2015). Comparison of insect invasions in North America, Japan and their Islands. Biological Invasions, 17, 3049–3061. 10.1007/s10530-015-0935-y [CrossRef] [Google Scholar]

Posted by Faith Campbell

We welcome comments that supplement or correct factual information, suggest new approaches, or promote thoughtful consideration. We post comments that disagree with us — but not those we judge to be not civil or inflammatory.

What the VLB Saga Tells Us About Detection Surveys

Setting Priorities for Surveillance

CBP inspects a pallet suspected for harboring an insect pest

Despite Customs and Border Protection’s heroic efforts to target inspection of wood packaging shipments, based on histories of non-compliance of specific importers’ wood packaging (which I have often praised), the majority of larvae occurring in wood packaging would probably not be intercepted by inspectors. Instead, they would be transported to the cargo’s intended destinations (Wu et al. 2020). I described these problems in the preceding blog about the velvet longhorned beetle (VLB).

As I have noted in the past, CBD detects an average of 800 shipments per year with non-compliant wood packaging. That figure is less than five percent of the 16,500 infested shipping containers that might enter the country each year, based on the estimate by Haack et al., (2014) that one tenth of one percent of incoming wood packaging might be infected.

So there is always a need to improve surveillance for pests that inspection fails to catch. We can do that in at least the following ways:

1) better target detection efforts on the most likely areas where a pest might establish

2) improve collection and use of pest-related information to determine probable hosts, pathways of movement, and potential impacts.

Discovering How the Pest Moves

Sometimes improvements must be linked to individual species – although assisted by knowledge about species with similar life histories, e.g., similar hosts or flight periods or about its close relatives (see Ray’s development of a VLB lure; full citation at end of this blog).  

Other times, improvements might result from more generalizable adjustments.

For example, the pathway analysis undertaken by Krishnankutty and colleagues is one approach to improving geographic targetting. They analyzed aspects of  the velvet longhorned beetle’s pathways of introduction: 1) the types of imports associated with VLB-infested wood packaging; 2) ports where the beetle has been detected in recent years; plus 3) the presence and calculated probable volume of imports for the types of commercial operations considered likely to transport the beetle.

This analysis required access to detailed data from many sources. They included 1) interception data revealing the types of products most often associated with infested wood and the intended destinations of intercepted cargoes; 2) the North American Industry Classification System data listing locations of businesses likely to utilize these products; 3) the beetle’s climatic requirements; and 4) the locations of actual detections of VLB as revealed by Cooperative Agricultural Pest Survey (CAPS) and other trapping programs.

Approaches to Learning More

a Lindgren funnel trap

Relying on traps to detect new pests has several advantages. These include the relative ease of scaling up to larger areas, and – sometimes — the ability to use general lures that attract a variety of insects. Some insects are attracted only, or primarily, to specific lures. Labor intensiveness (and expense) varies with how many traps must be deployed, whether the sites are easily accessible, difficulty extracting trapped insects, and the difficulty sorting the dead insects to find the species of interest.

A second approach is more labor-intensive and expensive, but it gives more information on the target species. This approach is to rear intercepted insect larvae in logs inside containers (to prevent escape) until they reach maturity and emerge. This approach facilitates determination of the species (it is difficult to identify larvae) … and allows an evaluation of feeding behavior – which translates into assessment of the damage caused to the tree.

The Canadian Food Inspection Agency (CFIA) began applying this survey method in 2006. CFIA collects logs from trees in declining health at high risk sites, such as industrial zones, current and historic landfills, and disposal facilities where large volumes of international wood packaging and dunnage are stored for extended periods of time. The logs are obtained from trees removed as part of municipal hazard tree removal programs. CFIA takes the logs to one of four research laboratories (in Toronto, Nova Scotia, Montreal, and North Vancouver), where they are placed in rearing chambers and allowed time to see what insects emerge. The logs are also dissected to reveal the type of damage caused by the insects – that is, determine whether insect was cause of tree mortality [Bullas-Appleton et al. 2014) .

The United States is applying the same approach, but less systematically.

APHIS developed a short-term project aimed at addressing two challenges: identifying larvae found in wood packaging to the species level (larvae intercepted at the border are often identified only to family); and gaining valuable information about the failure of currently required phytosanitary treatments as regards particular genera and species.

In a cooperative project begun in 2012, the DHS Bureau of Customs and Border Protection (CBP) collected live larvae of Cerambycidae and Buprestidae (and, since September of 2015, Siricidae), intercepted during inspection at initially six, later 11 U.S. ports.

mesh bags in which APHIS is rearing larvae obtained from wood packaging inspected by CBD at ports of entry
photo by USDA APHIS

These larvae were sent to an APHIS containment facility where many were reared to adults. Upon emergence, adult specimens were killed and identified by experts working for the National Identification Service. DNA barcodes of dead larvae and the reared adults were defined and compared and any  new information was added to public genetic databases. These DNA barcodes have enhanced the capacity of anyone involved in pest interception and detection to rapidly identify larval stages. In 2017, APHIS determined that it had detected almost the full range of species that might be transported in wood packaging, and stopped funding the project.

As of June 2017, the APHIS project had received 1,289 intercepted wood borers (1,052 cerambycids, 192 buprestids and 45 siricids) from 45 countries (See Nadel et. al 2017). The extensive analysis of velvet longhorned beetle described in my previous blog link was greatly assisted by the resulting data.

Cerambycid larva which was part of the study
photo USDA APHIS

Years before the APHIS project, USDA Forest Service wanted to try applying rearing techniques to aid early detection of insects in the country. At first, the scientists asked residents of Washington, D.C. to identify street trees that appeared to be infested with pests. Those trees were then cut and sections placed in rearing containers to allow scientists to determine what was causing the problem (Harvard Science).

The project was transferred in 2015 to Boston and New York. The Boston location is an arboretum; the advantage of this site is that it has 1) a diversity of tree species; 2) trained staff; and 3) detailed records of most trees on-site (Harvard Science). Project scientists now accept material from stressed, diseased, or dying trees. This material is loaded into sealed barrels and allowed two years for insects to emerge. Since 2015, project scientists have examined 8,605 beetles comprising 223 species. These studies have resulted in 16 new state records, records of some Scolytinae that are rarely collected from traditional trapping methods; documentation of  new host associations; and discovery of one previously undescribed species — Agrilus sp. 9895 (See DiGirolomo, Bohne and Dodds, 2019).

SOURCES

Bullas-Appleton, E., T. Kimoto, J.J. Turgeon. 2014. Discovery of Trichoferus campestris (Coleoptera: Cerambycidae) in Ontario, Canada and first host record in North America. Can. Entomol. 146: 111–116 (2014).

Marc DiGirolomo, Michael Bohne, Kevin Dodds. 2019. Presentation to the 19th Annual Meeting of the Continental Dialogue on Non-Native Forest Insects and Diseases https://continentalforestdialogue.files.wordpress.com/2019/12/bohne.continentaldialogue1.pdf  USFS – Durham, NH – 19th Dialogue meeting

Haack, R. A. 2006. Exotic bark- and wood-boring Coleoptera in the United States: recent establishments and interceptions. Can. J. For. Res. 36: 269–288.

Haack RA, Britton KO, Brockerhoff EG, Cavey JF, Garrett LJ, et al. (2014) Effectiveness of the International Phytosanitary Standard ISPM No. 15 on Reducing Wood Borer Infestation Rates in Wood Packaging Material Entering the United States. PLoS ONE 9(5): e96611. doi:10.1371/journal.pone.0096611

Krishnankutty, S.M., K. Bigsby, J. Hastings, Y. Takeuchi, Y. Wu, S.W. Lingafelter, H. Nadel, S.W. Myers, and A.M. Ray. 2020. Predicting Establishment Potential of an Invasive Wood-Boring Beetle, Trichoferus campestris (Coleoptera: Cerambycidae) in the United States. Annals of the Entomological Society of America, 113(2), 2020, 88-99.  https://doi.org/10.1093/aesa/saz051    

Nadel, H. S. Meyers, J. Molongoski, Y. Wu, S. Lingafelter, A. Ray, S. Krishnankutty, A. Taylor.  2017. Identification of Port Interceptions in Wood Packing Material Cumulative Progress Report, April 2012 – June 2017

Ray, A.M., J. Francese, Y. Zou, K. Watson, D.J Crook, and J.G. Millar. 2019. Isolation and identification of a male-produced aggregation sex pheromone for the velvet longhorned beetle, Trichoferus campestris. Scientific Reports 2019. 9:4459. https://doi.org/10.1038/s41598-019-41047-x

Posted by Faith Campbell

We welcome comments that supplement or correct factual information, suggest new approaches, or promote thoughtful consideration. We post comments that disagree with us — but not those we judge to be not civil or inflammatory.

Have we dodged a bullet? (more like a burst of fire from a submachine gun)

Many highly damaging wood-borers have been introduced to North America in wood packaging.

One woodborer, a beetle in the Cerambycidae, has been introduced multiple times to the United States — both before and after implementation of ISPM#15, the international regulations designed to stop such introductions. This is the velvet longhorned beetle (VLB) (Trichoferus (=Hesperophanes) campestris). Independent scientists have recently documented how VLB is introduced and where it is established.

I first blogged about the VLB three years ago. At that time, I asked why APHIS had not undertaken a quarantine and other actions to contain or eradicate the beetle, which was clearly established in an orchard in Utah (Wu et al. 2020; full source citations appear at the end of the blog). Now, the VLB is established in three states and has been detected in many more (details below).

It appears that the VLB will not cause significant damage. I hope this proves true, because it is certainly travelling here on a regular basis. While the most detailed study of the VLB’s potential impact in North America is not yet complete, early indications are that the beetle attacks mostly dying or dead trees.

A Widespread and Adaptable Pest

The VLB is native to China, Central Asia, Japan, Korea, Mongolia, and Russia. It has also been recorded in several European countries. The risk of introduction is broader, however. VLB has established throughout the Middle East and Europe, as well as parts of South and Central America. U.S. officials have intercepted live VLB individuals in shipments originating from these introduced populations, i.e., Brazil, Italy, Mexico, and Spain (Ray et al. 2019).

Wu et al. (2020) studied the genetic diversity of VLB specimens collected by in the United States by 1) trapping at several locations and 2) by testing those intercepted in wood packaging at U.S. ports. The scientists found high levels of diversity between and even within each limited geographic population. These results indicate that VLB has been introduced numerous times via the wood packaging pathway. They also found some evidence that introduced VLB populations might be expanding so it is important to understand pathways of spread within the country (Wu et al. 2020).

Where VLB is in the United States

The VLB is now officially considered to be established in Cook and DuPage counties, IL; Salt Lake County, UT; and Milwaukee, WI. [Krishnankutty et al. 2020).

However, adults have been detected in 26 counties in 13 additional states, plus Puerto Rico, since 1992. Since a trapping survey for woodborers began in 1999, this joint federal and state Cooperative Agricultural Pest Survey (CAPS) has trapped VLB in Colorado (2013), Illinois (2009), New Jersey (2007, 2013), New York (2014, 2016–2018), Ohio (2009, 2017–2019), Pennsylvania (2016), Rhode Island (2006), and Utah (2010, 2012–2019). (Krishnankutty et al. 2020). Also, Oregon detected VLB in 2019 (Oregon Department of Agriculture 2019).

Interceptions in Wood Packaging

The velvet longhorned beetle has been detected frequently in wood packaging since at least the middle 1980s (when APHIS began recording interceptions) (Haack 2006). (Haack’s study covered 1985-2000, before implementation of the International Standard on Phytosanitary Measures (ISPM) #15.)

APHIS’ official interception database listed 60 separate interceptions of VLB in the more recent ten plus-year period June 1997 – November 2017 – which overlaps pre- and post-implementation of ISPM#15. Eighty-eight percent of these interceptions were in wood packaging. Seven percent were in wood products. The remaining seven percent were in passenger baggage or unidentified products.

As has been the case generally since ISPM#15 was adopted, a high percentage — 65.4% — of the intercepted wood packaging during this period bore the mark certifying compliance with the ISPM#15 treatment requirements. Unsurprisingly, China was the origin of 81.6% of the intercepted shipments infested by pests (Krishnankutty et al. 2020).

In the most recent data studied, all from the period after implementation of ISPM#15 — 2012 – 2017, 28 VLB were found in analyses of a sample of wood packaging (Nadel et al. 2017). (I will discuss this study and other detection tools in a separate blog.)

In agreement with earlier findings, the most high-risk imports were determined to be wood packaging for stone, cement, ceramic tile, metal, machinery, manufactured wood products (furniture, decorative items, new pallets, etc.), and wood-processing facilities (Krishnankutty et al. 2020).

These findings largely confirm what we already know about the wood packaging pathway and high levels of non-compliance with ISPM#15 by Chinese shippers. What is APHIS going to do about this well-documented problem? APHIS certainly shouldn’t ignore these findings on the grounds that this particular wood-borer is less damaging than many others. Any chink in our phytosanitary programs that allows transport and entry of VLB can – does! – allow introduction of other woodborers.

The VLB also has been found in rustic furniture – often after the furniture has been sold to consumers. I discussed a 2016 example of this pathways in my February 2017 blog. Krishnankutty et al. (2020) suggest other possible pathways are wooden decorative items and nursery stock, particularly penjing (artificially dwarfed trees and shrubs).

Krishnankutty et al. (2020) note the importance of proper disposal of wood packaging once the cargo reaches its destination. Have any state phytosanitary officials enacted regulations targetting this source of invaders?

The Risk to North America’s Forests Is Unknown

A climate-based model described in Krishnankutty et al. (2020) suggests that climate appears to be suitable for VLB across much of the continental United States, northern Mexico, and southern Canada. Only Florida, southern Texas, and high elevation and coastal regions of the western United States and Mexico states are unlikely to support the velvet longhorned beetle, based on climate. (The study did not consider whether host trees would be present.)

Asian and European sources list a broad host range consisting of at least 40 genera of conifers, hardwoods, and fruit trees (Krishnankutty et al. 2020). Still, as noted above, new studies seem to indicate a minimal impact on healthy trees in North America. Indeed, the principal Utah outbreak is in an orchard littered with pruned material.

With so many suitable hosts across so much of the country, the potential for damage is frightening.

Setting Priorities for Surveillance

The availability of data on both port interceptions and multiple detected outbreaks provides an opportunity to test procedures for carrying out early detection surveys. Improving the efficacy of early detection is critical since – as Wu et al. (2020) note – — the majority of infesting larvae would probably not be intercepted and would subsequently be transported to the cargo’s intended destinations. This is despite CBP’s best efforts to target inspection of wood packaging shipments based on shippers’ histories of non-compliance, targeting that I strongly support.

In response to this concern, Krishnankutty et al. (2020) analyzed pathways of introduction – 1) the types of imports associated with VLB-infested wood packaging, 2) ports where the beetle has been detected in recent years, plus 3) the presence and calculated probable volume of imports of types of commercial operations considered likely to transport the beetle. These included wholesale and retail sellers of products known to be risky and businesses involved with wood fuel processing, log hauling, logging, and milling of saw lumber (Krishnankutty et al. 2020).

They could test the value of this approach by comparing the calculated “intended destination counties” declared at import to actual detections of T. campestris. VLB was detected (by CAPS or other surveys) in either the same or a neighboring county for 40% of the intended destination counties.

This seems to be a high introduction rate; detections will probably rise now that a species-specific lure is available. What could this mean for the establishment rate? Is anyone going to repeat the comparisons to track such changes? Unfortunately, we lack sufficient data to compare the VLB establishment rate (whatever it turns out to be) to the rate for other wood-borers.

Focusing on their original intentions, Krishnankutty and colleagues considered the 40% correlation between intended destinations and VLB detections to be sufficiently rewarding to be one basis for setting priorities for surveys (Krishnankutty et al. 2020).

Krishnankutty et al. (2020) say that recognition of three established populations and widespread destinations of potentially infested wood packaging to climatically suitable areas points to the need to determine whether additional populations are already established – or might soon become so. I add this need is further supported by the frequent detections of low numbers of the VLB in at least seven other states (see above). They call for enhanced surveillance to determine where the VLB is.

Improved surveillance is now facilitated by Dr. Ann Ray’s identification of a specific pheromone that can be synthesized in a lab and used to lure VLB to traps. The pheromone is much more effective in attracting VLB than previous food-like lures used by CAPS as general-purpose attractants for wood-boring insects.APHIS had provided about $50,000 over four years from the Plant Pest and Disease Management and Disaster Prevention program (which receives funding through the Farm Bill) to Dr. Ray’s search for the species-specific pheromone.

what happens when detection fails –
dead champion green ash in Michigan

I will discuss detection efforts in a separate blog.

SOURCES

Bullas-Appleton, E., T. Kimoto, J.J. Turgeon. 2014. Discovery of Trichoferus campestris (Coleoptera: Cerambycidae) in Ontario, Canada and first host record in North America. Can. Entomol. 146: 111–116 (2014).

Haack, R. A. 2006. Exotic bark- and wood-boring Coleoptera in the United States: recent establishments and interceptions. Can. J. For. Res. 36: 269–288.

Krishnankutty, S.M., K. Bigsby, J. Hastings, Y. Takeuchi, Y. Wu, S.W. Lingafelter, H. Nadel, S.W. Myers, and A.M. Ray. 2020. Predicting Establishment Potential of an Invasive Wood-Boring Beetle, Trichoferus campestris (Coleoptera:) in the United States. Annals of the Entomological Society of America, XX(X), 2020, 1–12

Nadel, H. S. Meyers, J. Molongoski, Y. Wu, S. Lingafelter, A. Ray, S. Krishnankutty, A. Taylor. 2017. Identification of Port Interceptions in Wood Packing Material Cumulative Progress Report, April 2012 – June 2017

Oregon Department of Agriculture, Plant Protection & Conservation Programs. 2019. Annual Report 2019.

 Ray, A.M., J. Francese, Y. Zou, K. Watson, D.J Crook, and J.G. Millar. 2019. Isolation and identification of a male-produced aggregation sex pheromone for the velvet longhorned beetle, Trichoferus campestris. Scientific Reports 2019. 9:4459. https://doi.org/10.1038/s41598-019-41047-x

Wu, Y., S.M. Krishnankutty, K.A. Vieira, B. Wang. 2020. Invasion of Trichoferus campestris (Coleoptera: Cerambycidae) into the United States characterized by high levels of genetic diversity and recurrent intros. Biological Invasions Volume 22, pages1309–1323(2020)

Posted by Faith Campbell

We welcome comments that supplement or correct factual information, suggest new approaches, or promote thoughtful consideration. We post comments that disagree with us — but not those we judge to be not civil or inflammatory.

Happy 14th Anniversary for Wood Packaging? Probably Not: Noncompliance, Fraud, and Missing Data

CBP inspectors examining pallet
CBP photo

This month is the 14th anniversary of United States’ implementation of International Standard for Phytosanitary Measure (ISPM) #15 with the goal of reducing the risk of pest introduction via wood packaging. 

Implementation of the international standard has apparently reduced the “approach rate” of pests in wood packaging, but not sufficiently (See my previous blog).

In this International Year of Plant Health (USDA/APHIS full citation at end of this blog), it is essential to understand how well the wood packaging program is working. Evaluating its current efficacy is especially important for protecting our forests. One key scientific society recognizes this: organizers of  the Entomological Society of America’s Grand Challenges Summit in Orlando next November have chosen wood packaging as the theme.  

Unfortunately, information essential to evaluate the efficacy of ISPM#15 – both worldwide and as implemented by USDA APHIS – is not yet available.

Our most up-to-date information on U.S. enforcement is from Kevin Harriger, Executive Director for the Agriculture Programs and Trade Liaison office, U.S. Customs and Border Protection (CBP). In his report to the annual meeting of the Continental Dialogue of Non-Native Forest Insects and Diseases in November 2019, he stated that over the past three years, CBP detected a regulated pest, on average, in 30% of wood packaging intercepted because it was not compliant with ISPM#15. Unfortunately, Mr. Harriger did not provide the actual number of shipments inspected or seized.

The absence of specific numbers means I cannot compare the 2019 findings to previous years. My calculation of Mr. Harriger’s data provided to the Dialogue in previous years showed that over the nine-year period Fiscal Years 2010 through 2018, CBP detected 9,500 consignments harboring a regulated pest. Ninety-seven percent of the shipments found to be infested with a pest bore the ISPM#15 mark. The wood packaging was from nearly all trading countries. CBP staff say the reason for this high proportion of pests in wood packaging is fraud.

A European study of imports of stone from China over the period 2013-2016 focused on a recognized high-risk commodity. Nevertheless, the Europeans reached the same finding: 97.5% of consignments that harbored pests bore the ISPM#15 mark. They concluded that the ISPM-15 mark was of little value in predicting whether harmful organisms were present (Eyre et al. 2018).

There is considerable dispute about which categories of packaging are most likely to be infested. The categories are pallets, crates, spools for cable, and dunnage (wood used to brace cargo and prevent it from shifting). Unfortunately, Mr. Harriger shed no light on that issue. He did report that 78% of non-compliant shipments over the last three years was in packaging associated with “miscellaneous cargo”, e.g., machinery, including electronics; metals; tile and decorative stone (such as marble or granite counter tops). This association has been true for decades (see Haack et al. 2014). Another 20% of the non-compliances were associated with fruit and vegetable cargoes. This probably reflects the combination of large volumes of produce imports from Mexico and that country’s poor record of complying with wood packaging requirements.

It has been reported that in recent years, CBP inspectors have repeatedly found pests in dunnage bearing the ISPM#15 mark and associated with “break bulk” cargo (goods that must be loaded individually; not transported in containers or in holds as with oil or grain). Ships that carry this sort of. Problems appear to be acute in Houston. While most of the criticism of non-compliant wood packaging refers to countries in Asia and the Americas, at least one of the Houston importers obtains its dunnage in Europe.

There is even a question about the volume in incoming goods. CBD says that approximately 13 million loaded containers enter the country every year by rail, truck, air, or sea.  However, my calculation from U.S. Department of Transportation data (see reference) was that more than 22 million shipping containers entered the U.S. via maritime trade in 2017.

In 2017, CBP announced a new policy under which it will assess a penalty on each shipment in which the wood packaging does not comply with ISPM#15. Previously, no penalty was assessed until a specific importer had amassed five violations over a twelve-month period.

FY2019 was thus the second year under the new policy. I had hoped that Mr. Harriger would provide information on the number of penalties assessed and any indications that importers are strengthening their efforts to ensure that wood packaging complies. However, he did not.

He did report that CBP has expanded outreach to the trade. The goal is reducing all types of non-compliance – lack of documentation, pest presence, etc. in both wood packaging and shipping containers. Outreach includes awareness campaigns targetting trade, industry, affiliated associations, CBP employees, and international partners.

Still, authorities cannot know whether the actual “approach rate” of pests in wood packaging has changed in response to CBP’s strengthened enforcement because they lack a scientifically valid study. The most recent study – that reported in Haack et al. 2014 – relied on data up to 2009 – more than a decade ago. It indicated an approach rate of approximately 0.1% (Haack et al. 2014).

Unfortunately, USDA APHIS has not yet accepted researchers’ offer to update this study.

We do know that pests continue to be present in wood packaging 14 years after the U.S. put ISPM#15 into force.

I call for:

1) Determining the relative importance of possible causes of the persistent pest presence problem – fraud, accidental misapplication of treatments, or other failures of treatment;

2) Enhanced enforcement by APHIS as well as CBP;

3) Stepped up efforts to help US importers by APHIS and  the Foreign Agricultural Service– by, e.g., providing information on which foreign suppliers of wood packaging and dunnage have good vs. poor records; conveying importers’ complaints about specific shipments to the exporting countries’ National Plant Protection Organizations (NPPOs), such as Departments of Agriculture;

4) Raising pressure on foreign NPPOs and the International Plant Protection Convention more generally to ascertain the specific reasons ISPM#15 is failing and to fix the problems identified.

Alernative Materials – Plastic!

I have also advocated for shifting at least some wood packaging e.g., pallets and some crates – to alternative materials. For example, USDA APHIS could require exporters with bad records to use crates and pallets made from materials other than solid wood, e.g., plastic, metal, or oriented strand board. Or companies could make that shift themselves to avoid phytosanitary enforcement issues and penalties.

People recoil from the idea of using plastic and there are increasing concerns about the breakdown of plastics into tiny fragments, especially in water. But it’s also true that the world is drowning in plastic waste. Surely some of this could be recovered and made into crates and pallets with environmentally sound technology.

The Washington Post reported in November that an Israeli company is converting all kinds of trash – including food waste – into plastic, and molding that plastic into various items, including packing crates.

UBQ Materials takes in tons of rotting food, plastic bags, dirty paper, castoff bottles and containers, even broken toys. It then sorts, grinds, chops, shreds, cleans and heats it mess into first a slurry, then tiny pseudo-plastic pellets that can be made into everyday items like trays and packing crates.

Another Israeli company, Plasgad, uses plastic to make pallets, crates and other products.

Some who were skeptical now are more interested, including the president of the International Solid Waste Association  and the chief executive of the Plastic Expert Group. 

So – can we address three environmental problems at the same time – mountains of waste, methane gas releases contributing to climate change, and one (important) pathway for the movement of tree-killing pests?

SOURCES

Eyre, D., R. Macarthur, R.A. Haack, Y. Lu, and H. Krehan. 2018. Variation in Inspection Efficacy by Member States of SWPM Entering EU. Journal of Economic Entomology, 111(2), 2018, 707–715)

Haack RA, Britton KO, Brockerhoff EG, Cavey JF, Garrett LJ, et al. (2014) Effectiveness of the International Phytosanitary Standard ISPM No. 15 on Reducing Wood Borer Infestation Rates in Wood Packaging Material Entering the United States. PLoS ONE 9(5): e96611. doi:10.1371/journal.pone.0096611

Harriger, K., Department of Homeland Security Bureau of Customs and Border Protection, presentation to the Continental Dialogue on Non-Native Forest Insects and Diseases, November 2017.

U.S. Department of Transportation, Maritime Administration, U.S. Waterborne Foreign Container Trade by U.S. Customs Ports (2000 – 2017) Imports in Twenty-Foot Equivalent Units (TEUs) – Loaded Containers Only.

U.S. Department of Agriculture, Press Release No. 0133.20, January 27, 2020

Posted by Faith Campbell

We welcome comments that supplement or correct factual information, suggest new approaches, or promote thoughtful consideration. We post comments that disagree with us — but not those we judge to be not civil or inflammatory.

New Ambrosia Beetle in California – Threat to Oaks?

valley oak at Jack London State Park (24 miles from Calistoga)

In November, scientists discovered a new ambrosia beetle in symptomatic valley oaks  (Quercus lobata) trees in Calistoga, Napa County. Some blue oaks (Q. douglasii) have also been attacked (Rabaglia et al. 2020). Trees associated with this outbreak showed wilting, defoliation, and broken branches. The infested wood was discolored, presumably by the fungus. The insect, Xyleborus monographus, is native to Europe.

Officials now know that this beetle is found throughout a 15-mile-long area in Napa and neighboring Lake and Sonoma counties. It has probably been there for several years (Rabaglia et al. 2020). One specimen of the beetle was trapped in Portland, Oregon in 2018, but no infestation was detected. The beetle has never been intercepted in California. Nor has it been found in traps designed to detect bark beetles which have been deployed in 11 counties – including several in the San Francisco Bay area but not including Napa or Sonoma.

Like all Xyleborus, adult females tunnel into tree’s trunks, carrying fungal spores in their mycangia (structures in the jaws in which microbes are harbored). Beetle larvae eat the fungi. Beetle reproduction is facilitated by sibling mating within the gallery and by the ability of unmated females to produce male offspring.

Sometimes the beetle’s associated fungi are pathogenic to living trees. One of the fungal species detected in the Calistoga infestation is Raffaelea montetyi, which is reported to be pathogenic to cork oak. The presence of this fungus had been reported in 2018, although the beetle species carrying it was not identified then. This is apparently the first report of this fungus in North America.

Known hosts of beetle X. monographus include European or Eurasian chestnut (Castanea sativa), beech (Fagus orientalis), and European and American oaks (including Q. lobata and Q. rubra).  The possible effects of the beetle and associated fungi on other oak species is unknown. Oaks are acknowledged to be important components of forests and woodlands in California. Ambrosia beetles often attack stressed trees. Since California forests are increasingly frequently stressed by drought, fire, and other pests, they might be especially vulnerable.

The California Department of Food and Agriculture is currently seeking comments on what pest rank to assign the insect.  The comment period closes on March 6th and I encourage you to consider providing your views.

In their draft document ranking risk, state officials note that a proven host — Q. lobata — is widespread in California and the insect is probably capable of establishing over much of the state. The possible economic impact was described as possibly affecting production of oaks in California nurseries and triggering quarantines.  (Does this mean CDFA expects impacts only on saplings? Is this realistic? CDFA made no mention of costs to urban areas for hazard tree management.)

The risk assessment notes that research by McPherson, et al. (2008) found that ambrosia beetles are attracted to oak trees already infected with sudden oak death (SOD) (Phytophthora ramorum). Therefore, X. monographus could have a synergistic impact with SOD on California oaks – which has already killed an estimated 1.9 to 3.3 million coast live and Shreve oaks.

SOURCE

Rabaglia, R.J. S.L. Smigh, P. Rurgman-Jones, M.F. Digirolomo, C. Ewing, and A. Eskalen. 2020. Establishment of a non-native xyleborine ambrosia beetle, Xyleborus monographus (Fabricius) (Coleoptera: Curculionidae: Scolytinae), new to North America in California. Zootaxa 478 (2): 269-276

Posted by Faith Campbell

We welcome comments that supplement or correct factual information, suggest new approaches, or promote thoughtful consideration. We post comments that disagree with us — but not those we judge to be not civil or inflammatory.

ISPM#15 – The Stamp is Not Effective as a Clue to Whether Wood Packaging is Pest-Free

For more than a decade, most countries in the world have required that crates, pallets, spools, and dunnage made from wood be treated in accordance with the requirements of the International Standard for Phytosanitary Protection (ISPM)#15 that this treatment be certified by applying an approved stamp to the wood. The goal of the program is to “reduce significantly the risk of introduction and spread of most quarantine pests that may be associated with that material.”

However, experience and studies in both the United States and Europe demonstrate that the ISPM#15 stamp is not a reliable indicator of whether the wood packaging is pest-free.

1) In the United States, over a period of nine years – Fiscal Years 2010 through 2018 – U.S. Customs and Border Protection (CBP) detected 9,500 consignments harboring a pest in a regulated taxonomic group. Of the shipments found with infested wood packaging, 97% bore the ISPM#15 mark (See Harriger reference at the end of the blog). The wood packaging was from nearly all trading countries. 2) In the past two years, CBP inspectors have repeatedly found pests in dunnage bearing the ISPM#15 mark – as reported by U.S. importers of “break bulk” cargo into Houston. While most of the criticism of non-compliant wood packaging refers to countries in Asia and the Americas, at least one of the Houston importers obtains its dunnage in Europe.

3) In Europe, a two-year intensive survey of wood packaging associated with shipments of stone from China to the 28 European Union countries over the period 2013-2016 again found that 97.5% of consignments found to harbor pests bore the ISPM#15 mark (Eyre et al. 2018). The scientists concluded that the ISPM-15 mark was of little value in predicting whether harmful organisms were present. (Eyre et al. 2018, p. 712)

As I have noted in previous blogs and policy briefs, the only in-depth study of the “approach rate” of pests in wood packaging, based on data which is now a decade old, found that 0.1% of incoming wood packaging transported a regulated pest (Haack et al. 2014). Given current trade volumes, as many as 17,650 containers per year (or 48 per day) transporting tree-killing insects might be entering the U.S. (My calculation of this estimate is explained in the blog on “risks of introduction” here.)

The Haack study excluded imports from Mexico, Canada, and China. The first and third countries have records of poor compliance with ISPM#15 requirements, so the “approach rate” for all incoming shipments might well have been higher.

The study of European imports focused on shipments of stone from China – which were deliberately chosen to represent types of imports presenting a high risk of transporting pests. Across Europe, over the four-year period, quarantine pests were detected in 0.9% of the consignments – somewhat higher than the U.S. number, as could be expected. However, there were large variations among participating countries’ findings. Austria and France found 6.95% of consignments inspected were infested, while half of European Union countries found none!

These differences demonstrate the importance of thorough inspections.

The data also indicate that the problem is not decreasing. Austria detected pests in nearly one-fifth (19.6%) of inspected shipments in 2016 – the final year of the study! However, during that same year, only 1.5% of wood packaging lacked the ISPM#15 mark.

So How Should the International Phytosanitary Community React to This Failure?

Data cited in numerous studies indicate that ISPM#15 has probably succeeded in reducing the presence of pests in wood packaging. This progress is good – but insufficient. Our forests need further reductions.

In the meantime, however, the international standard has demonstrably failed to provide a secure method to evaluate the pest risk associated with wood packaging accompanying any particular shipment. The presence of the stamp on pieces of wood packaging does not reliably show that the wood is pest-free. Officials need to determine why. Is it fraud? That would mean deliberately placing the stamp on wood that had not been treated, which U.S. CBP staffers think is occurring (Harriger). The European Union audit team that visited China also thought they detected instances of fraud. They concluded that “the current system of official controls in China does not adequately ensure that SWPM which forms part of consignments of goods exported to the EU is marked and treated according to ISPM No. 15” (Eyre et al. 2018, p. 713). On the other hand, the US importers in Houston say they are pressing their European suppliers to provide pest-free dunnage.

What more could we ask them to do to ensure that they are not receiving fraudulently marked materials?

Perhaps the problem has a different cause. Are the treatments themselves are less effective than expected? One APHIS study found that twice as many larvae reared from wood treated by methyl bromide fumigation survived to adulthood than larvae reared from heat-treated wood; the reason is unclear (Nadel et al. 2016). Unfortunately, it is apparently impractical to determine whether wood was heat treated by looking for changes in the chemical profile of the wood (Eyre et al. 2018).

Nor can we expect inspection of 100% of all risky consignments or detection of 100% of quarantine pests in those consignments that are inspected. Therefore, the European study authors concluded that inspection is best considered as a means of gathering evidence of risk and a deterrent rather than a means of completely preventing pest movement (Eyre et al. 2018).

The European study authors called for review of ISPM#15 as a control system and to investigate compliance at the source (Eyre et al. 2018 p. 714).

What is APHIS doing?

As I have noted previously – here and here – while U.S. CBP adopted a policy in 2017 under which it can penalize importers for each consignment not in compliance with ISPM#15, APHIS has not followed Custom’s lead on this. Instead, APHIS will apply a penalty only when an importer has accrued five violations over the period of a year. (The two agencies are acting under separate legal authorities.) This is yet another example of APHIS taking a less protective stance – as I described in earlier blogs.

Since Customs is now applying the letter of the law, the most useful step would probably be for APHIS (and the USDA Foreign Agriculture Service) to ramp up efforts to assist U.S. importers which are trying to comply. The importers are begging USDA to provide better information to them about foreign suppliers of wood packaging and dunnage. Which have good vs. poor records? USDA could also help importers trying to complain about specific shipments to the exporting countries’ National Plant Protection Organizations (NPPOs; departments of agriculture).  In addition, APHIS could augment its pressure on foreign NPPOs and the International Plant Protection Convention more generally to ascertain the reasons ISPM#15 is failing and to fix the problems.

APHIS has not been idle. The North American Plant Protection Organization (including Canada and Mexico) has sponsored two workshops intended to educate NPPOs and exporters in Asia and the Americas about the standard’s requirements. APHIS is planning to address wood packaging in an international symposium organized under the auspices of the International Year of Plant Health in July 2020 – I will provide details when they become available.

APHIS is collaborating with the Entomological Society of America to host a workshop on wood packaging at the ESA annual meeting in November 2020 – I will provide details when they become available. The Continental Dialogue on Non-Native Forest Insects and Diseases plans to link its annual 2020 meeting to this workshop.

More immediately, the Continental Dialogue on Non-Native Forest Insects and Diseases will have presentations on the wood packaging issue at its annual meeting in just 11 days! in Cleveland

In preparation for the 2020 meetings, APHIS should fund more studies and audits of wood packaging to document the current efficacy of the standard (that is, the pest approach rate); remember, Haack’s study relied on data which are now a decade old. Not only has time passed … Both the standard and U.S. enforcement policies have changed since 2009.

Significance of the Wood Packaging Problems

The apparent failure of the ISPM#15 standard to provide a reliable means to certify treatment raises obvious issues regarding the risk of pest introductions. However, the implications are much broader.

The premise of the international phytosanitary system – the Agreement on the Application of Sanitary and Phytosanitary Standards (SPS Agreement) and International Plant Protection Convention (IPPC) – is that importing countries should rely on exporting countries to take the actions necessary to meet the importing countries’ plant health goals. The ISPM#15 experience casts doubt on this premise. The exporters are not reliably ensuring the cleanliness of their wood packaging. Worse, wood packaging is easier to treat than fruits, vegetables, and living plants (plants for planting). The latter commodities are much more easily damaged or killed by treatments than are boards or even logs – which are, after all, already dead! (A longer discussion of the SPS Agreement and IPPC is found in Chapter III of Fading Forests II, available here.

I hope that the international phytosanitary community will take advantage of the heightened attention and effort associated with the International Year of Plant Health in 2020 to re-examine all aspects of the current global phytosanitary system.

Posted by Faith Campbell

We welcome comments that supplement or correct factual information, suggest new approaches, or promote thoughtful consideration. We post comments that disagree with us — but not those we judge to be not civil or inflammatory.

SOURCES

Eyre, D., R. Macarthur, R.A. Haack, Y. Lu, and H. Krehan. 2018. Variation in Inspection Efficacy by Member States of SWPM Entering EU. Journal of Economic Entomology, 111(2), 2018, 707–715)

Kevin Harriger, US CBP. Presentations to the annual meetings of the Continental Dialogue on Non-Native Forest Insects and Diseases over appropriate years. See, e.g., https://continentalforestdialogue.org/continental-dialogue-meeting-november-2018/

Nadel, N., S. Myers, J. Molongoski, Y. Wu, S. Linafelter, A. Ray S. Krishnankutty, and A. Taylor. 2016. Identificantion of Port Interceptions in Wood Packaging Material: Cumulative Progress Report, April 2012 – August 2016

https://www.joc.com/breakbulk/ispm-15-enforcement-leaves-shippers-no-good-nswers_20190717.htmlhttps://www.joc.com/breakbulk/enhanced-enforcement-ispm-15-costing-us-importers-millions_20190725.html

Thirty Years of Tree Pest Analysis, Continued – Risks of New Introductions

It is widely recognized that invasions of non-native species occur as a consequence of international trade (see Seebens et. al. 2017 – full citations at the end of this blog). This is as true for non-native forest pests as for any other bioinvader – see Aukema et al. 2010; Liebhold et al. 2012, Lovett et al. 2016. In fact, gross domestic product – as an indicator of levels of trade — is a better predictor of the number of forest pest invasions in a given country than the country’s amount of forested land (Roy et al. 2014).

shipping containers at port of Long Beach, California

As I noted in my previous blog, I began studying and writing about the threat to North America’s forests from non-native insects and pathogens in the early 1990s. I reported my analyses of the evolving threat in the three “Fading Forests” reports – coauthored by Scott Schlarbaum – in 1994, 2003, and 2014. These reports are available here.

I document here that both introduction and spread of pests within the country have continued apace. While significant efforts have been made to prevent introductions (described briefly under the “Invasives 101” tab of the CISP website), they have fallen short. As I noted in Fading Forests III, programs aimed at preventing spread of pests within the country remain fragmented and often are unsuccessful.

The Challenge: Huge Volumes of goods are moving, providing opportunities for pests

Since 1990, volumes of imported goods more than quintupled. Within the U.S., a total of 17,978 million tons of goods were transported in 2015; 10,776 million tons of this total by truck. About one-third of this total – 5,800 million tons – was moved farther than 250 miles. These vehicles moved on a public roads network of 4,154,727 miles (US DOT FFA). Consequently, once a pest enters the U.S., it can be moved quickly into every corner of the country.

Introductions

By and large, establishment of tree-killing pests has occurred at a fairly steady rate of about 2.5 per year, with “high-impact” insects and pathogens accumulating at 0.43 per year (Aukema et al. 2010). Since introductions did not rise commensurately with rising import volumes, Lovett et al. (2016) concluded that the recently adopted policies for preventing introductions referenced above are having positive effects but are insufficient to reduce the influx of pests in the face of ever-growing global trade volumes. The study’s authors went on to say that absent more effective policies, they expect the continued increase in trade will bring many new establishments of non-native forest pests.

One group of forest pests did not enter at a steady rate, but rather entered at a higher rate since 1985 – wood-boring insects. Experts concluded that the increase probably reflected increases in containerized shipping (Lovett et al. 2016). At the global level, the rate of fungal invasions has also recently been reported to be increasing rapidly (Roy et al. 2014).

Asian longhorned beetle

Geography of trade patterns also matters. Opening of trade with China (in 1979) offered opportunities for pests from a new source country which has a similar climate and biology. Roy et al. describe the importance of phylogenetic relatedness of pests and of tree hosts in explaining tree species’ vulnerability to introduced pests. The most vulnerable forests are those made up of species similar to those growing in the source of the traded goods – i.e., the temperate forests of the northeastern U.S. – when goods are imported from similar forested areas of Europe and Asia. Chinese-origin wood-boring pests began to be detected around 1990. This already short interval probably underestimates how quickly pests began arriving; detection methods were poor in those years, so a pest was often present for close to a decade before detection.

Between 1980 and 2016, at least 30 non-native species of wood- or bark-boring insects in the Scolytinae / Scolytidae were newly detected in the United States (Haack and Rabaglia 2013; Rabaglia et al. 2019).  Over the same period, approximately 20 additional tree pests were introduced to the continental states (Wu et al. 2017; Digirolomo et al. 2019; R. Haack, pers. comm.) plus about seven to America’s Pacific islands. Not all of the new species are highly damaging, but enough are. See my previous blog here.

Many of the tree-killing pests were probably associated with pathways other than wood packaging. These include 6 of the 7 Agrilus species, sudden oak death pathogen, three pests of palm trees, the spotted lanternfly, beech leaf disease; and the pests introduced to America’s Pacific Islands.

HIGH-RISK PATHWAYS OF INTRODUCTION

Already in the 1990’s it was evident that better preventing pest introductions would depend on shutting down the variety of pathways by which they move around the world.   At that time, attention focused on imports of logs and nursery stock (nursery stock makes up one component of a broader category called by phytosanitary agencies “plants for planting”). Both logs and “plants for planting” had well-established histories of transporting pests and import volumes were expected to grow. We have since learned that there are many more pathways!

Plants for Planting

Imports of “plants for planting” (phytosanitary agencies’ term, which encompasses nursery stock, roots, bulbs, seeds, and other plant parts that can be planted) have long been recognized as a dangerous pathway for introduction of forest pests. For example, this risk was the rationale for adopting the 1912 Plant Quarantine Act. Charles Marlatt, Chairman of USDA’s Federal Horticultural Board (see “Then and Now” in Fading Forests III here), wrote about the risk in National Geographic in April 1911 (urging adoption of the 1912 law) and again in August 1921. See also Brasier (2008), Roy et al. (2014), Liebhold et al. (2012), Jung et al. (2016).

Japanese cherry trees being burned because of scale infestation
January 28, 1910; Agriculture Research Service

Of the 91 most damaging non-native forest pest species in the U.S. (Guo et al. 2019), about 62% are thought to have entered North America with imports of live plants. These include nearly all the sap-feeding insects, almost 90% of the foliage-feeding insects, and approximately half of the pathogens introduced during the period 1860-2006 (Liebhold et al. 2012). Specific examples include chestnut blight, white pine blister rust, Port-Orford-cedar root disease, balsam woolly adelgid, hemlock woolly adelgid, beech scale, butternut canker, dogwood anthracnose, and sudden oak death. In more recent years, introductions via this pathway possibly include ‘ōhi‘a rust, rapid ‘ōhi‘a death pathogens, and beech leaf disease. The gypsy moth, while a foliage feeder, was not introduced via imports of live plants.

The APHIS annual report for 2018 reported that in that year we imported 18,502 shipments containing  more than 1.7 billion plant units (plants, bulbs, in vitro materials, etc.).

Liebhold et al. 2012, relying on 2009 data, found that about 12 percent of incoming plant shipments had symptoms of pests – a rate more than 100 times greater than that for wood packaging. Worse, a high percentage of the pests associated with a shipment of plants is not detected by the federal inspectors. The meaning of this finding is unclear because the study did not include any plant genera native to temperate North America and APHIS points out that infestation rates varied considerably among genera in the study. However, APHIS has not conducted its own analysis to document the “slippage rate” on imports of greatest concern to forest conservationists, i.e., imports of woody plants. I provide details on pests detected on imports of woody plants in recent in my blog here.

Clearly the risk of pest introductions continued at least until recently. I reviewed an APHIS database listing pests newly detected in the country during the period 2009-2013. I concluded that approximately 37 of the 90 “new” pests listed in the database (viruses, fungi, aphids and scales, whiteflies, mites) were probably introduced via imports of plants, cuttings, or cut foliage or flowers. I discussed these matters in greater detail here.

Adoption of a new regulatory regime governing imported plants for planting  (Q-37 regulation) in 2018 is too recent to for us to see its impact. But the new regulation sets up a process under which APHIS can impose more protective regulations on specific types of plants or plants from certain countries of origin to counter a perceived concerning level of risk. Until APHIS begins activating its new powers by negotiating more protective regulations governing plant imports from high-risk sources, it seems unlikely there will be any meaningful change in the introduction rates.

Crates, Pallets, and Other Forms of wood packaging (solid wood packaging, or SWPM)

Recognition of the risk associated with wood packaging is much more recent. In 1982, a USDA risk assessment concluded that the wood boring insects found in crates and pallets were not of great concern (USDA APHIS and Forest Service, 2000). However, contradictory indications were quickly documented – including from APHIS’ own port interception data – which the agency began collecting in 1985. Over the 16-year period 1985-2000, 72% of the 6,825 bark beetles (Scolytidae) intercepted by APHIS were found on SWPM (Haack 2002). Cerambycids (longhorned beetles) and buprestids (jewel beetles) make up nearly 30% of insects detected in wood packaging over the last 30 years (Haack et al. 2014).

Detection of outbreaks of the Asian longhorned beetle and other woodborers in the mid-1990s made it clear that wood packaging was, indeed, a high-risk pathway.

Of the 91 most damaging non-native pest species in the US, 30% probably arrived with wood packaging material or other wood products (Liebhold et al. 2012). This group includes many of the most damaging pests, the deadly woodborers – Asian longhorned beetle, emerald ash borer, redbay ambrosia beetle,  possibly the polyphagous and Kuroshio shot hole borers.

CBP agents inspecting a pallet

As noted above, introductions of wood borers have risen in recent decades, widely accepted as associated with the rapid increase in containerized shipping after 1980. In 2009 it was estimated that 75% of maritime shipments were packaged in crates or pallets made of wood (Meissner et al. 2009). A good history of the global adoption of containerized shipping is Levinson, M. The Box: How the Shipping Container Made the World Smaller and the World Economy Bigger (Princeton University Press 2008)

The simultaneous opening of trade with China (in 1979) offered opportunities for pests from a new source country which has a similar climate and biology. Chinese-origin wood-boring pests began to be detected around 1990. This already short interval probably underestimates how quickly pests began arriving; detection methods were poor in those years, so a pest was often present for close to a decade before detection.

I have already documented numerous times that, despite the U.S.’ implementation of the International Standard of Phytosanitary Measures (ISPM) #15 in 2006, live quarantine pest woodborers continue to enter the U.S. in wood packaging. The best estimate is that 0.1% of wood packaging entering the United States is infested with wood-borers considered to be quarantine pests (Haack et al. 2014). More than 22 million shipping containers entered the U.S. via maritime trade in 2017 (US DoT). As noted, an estimated 75% of sea-borne containers include wood packaging. Applying the 0.1% estimate to these figures results in an estimate that as many as 17,650 containers per year (or 48 per day) transporting tree-killing insects enter the U.S.

Over a period of nine years – Fiscal Years 2010 through 2018 – U.S. Customs and Border Protection (CBP) detected more than 28,600 shipments with wood packaging that did not comply with ISPM#15 (Harriger presentations to the annual meetings of the Continental Dialogue on Non-Native Forest Insects and Diseases). While most of the non-compliant shipments were wood packaging that lacked the required mark showing treatment per ISPM#15, in 9,500 cases the wood packaging actually harbored a pest in a regulated taxonomic group.

Disturbingly, 97% of the shipments that U.S. CBP found with infested wood packaging bear the ISPM#15 mark certifying that wood had been fumigated or heat-treated (Harriger 2017). CBP inspectors tend to blame this on widespread fraud in use of the mark. On the other hand, one study found that larvae can survive both treatments – although the frequency of survival was not determined. It was documented that twice as many larvae reared from wood treated by methyl bromide fumigation survived to adulthood than larvae reared from heat-treated wood; the reason is unclear (Nadel et al. 2016).

The APHIS’ record of interceptions for the period FYs 2011 – 2016 contained 2,547 records for insect detections on wood packaging. The insects belonged to more than 20 families. Families with the highest numbers of detections were Cerambycids – 25% of total; Curculionidae – 23% (includes Dendroctonus, Ips, Orthotomicus, Scolytinae, Xyleborus, Euwallacea); Scolytidae – 17% (includes true weevils such as elm bark beetles); Buprestids – 11%; and Bostrichidae – 3%. Not all of the insects in these groups pose a threat to North American plant species.

One encouraging data point is that since 2010, there have been no detections of species of bark and ambrosia beetles new to North America in the traps deployed by the USDA Forest Service Early Detection and Rapid Response program (Rabaglia 2019). The 2014 recognition of the Kuroshio shothole borer apparently did not result from this trapping program.

There have been several changes in the wood packaging standard and its implementation by CBP since 2009, the year Haack et al. 2014 analyzed the “pest approach rate”. APHIS has not carried out a study to determine whether these recent changes have reduced the approach rate below Haack’s estimate of 0.01%.  Consequently, we do not know whether these changes have reduced the risk of pest introductions.

Other Pathways That Transport  Fewer Pests –  Some of Which Have High Impacts

Insects that attach egg masses to hard surfaces can be transported by ship superstructures, containers, and hardsided cargoes such as cars, steel beams, and stone. While relatively few species have been moved in this way, some have serious impacts. The principal examples are the gypsy moths from Asia, which feed on 500 species of plants (Gibbon 1992). 

The United States and Canada have a joint program – under the auspices of the North American Plant Protection Organization (see RSPM #33) aimed at preventing introduction of species of Asian gypsy moths. The NAPPO standard originally went into force in March 2012. Under its terms, ships leaving ports in those countries during gypsy moth flight season must be inspected and cleaned before starting their voyage.

Gypsy moth populations rise and fall periodically; it is much more likely that egg masses will be attached to ships during years of high moth population densities. These variations are seen in U.S. and Canadian detection reports – as reported here.

While most AGM detections are at West Coast ports, [here;  and here] the risk is not limited to that region. AGM have been detected at Wilmington, NC; Baltimore, MD; Charleston, SC; Savanna and Brunswick, GA; Jacksonville, FL; New Orleans, LA; Houston and Corpus Christi, TX; and even McAlester, OK.  

Nor is the risk limited to the ships themselves. In 2014, more than 500 Asian gypsy moth egg masses were found on four shipments of imported steel slabs arriving at ports on the Columbia River in Washington.

Between 1991 and 2014, AGM was detected and eradicated on at least 20 occasions in locations across the United States (USDA AGM pest alert). Additional outbreaks have been discovered and eradication efforts undertaken in more recent years.

A second example is the spotted lanternfly (SLF) (Lycorma delicatula), which was first detected in southeast Pennsylvania in autumn 2014. It is native to Asia; it is believed to have entered the country as egg masses on imported stone.

While SLF is clearly a pest of agriculture – especially grapes and tree fruits – its importance as a forest pest is still unclear. Many native forest trees appear to be hosts during the insect’s early stages, including maples, birches, hickories, dogwoods, beech, ash, walnuts, tulip tree, tupelo, sycamore, poplar, oaks, willows, sassafras, basswood, and elms. Adult lanternflies strongly prefer the widespread invasive species tree of heaven (Ailanthus altissima).

As of August 2019, SLF was established in parts of five states: Delaware, Maryland, New Jersey, Pennsylvania, and Virginia. It was detected as having spread to a 14th county in Pennsylvania; five new counties in New Jersey. APHIS is working with state departments of Agriculture in these states, as well as supporting surveys in New York, North Carolina, and West Virginia (USDA APHIS DA-2019-20, August 7, 2019). Apparently the detections of a few adults – alive or dead – in Connecticut and New York had not evolved into an outbreak. See description and map here.

Imports of logs – roundwood – seem inherently risky. Certainly Dutch elm disease was introduced via this pathway. However, there have been few pest introductions linked to this pathway in recent years, probably because we import most of our unprocessed lumber from Canada. (I provide considerable data on U.S. roundwood imports in Fading Forests III here.)

Decorative items and furniture made of unprocessed wood certainly have the potential to transport significant pests (USDA APHIS 2007). Examples include boxes and baskets; wood carvings; birdhouses; artificial Christmas trees or other plants; trellises; lawn furniture. To date, apparently, no high-impact pest has been introduced via this pathway, although pests intercepted on shipments have included Cerambycids from Asia, e.g., velvet longhorned beetle and here.

Alarmed by high numbers of infested shipments from China, APHIS first suspended imports of such items temporarily; then adopted a regulation (finalized in March 2012 – USDA APHIS 2012).

APHIS has not taken action to prevent introductions on such items imported from other countries – although the North American Plant Protection Action adopted a regional standard making the case for such action and outlining a risk-based approach (NAPPO RSPM#38).

Snails on Shipping Containers

Snails have been detected on shipping containers and wood packaging for decades. In 2015, APHIS stepped up its efforts to address this risk through bilateral negotiations with Italy and launching regional and international efforts to develop guidance for ensuring pest-free status of shipping containers (Wendy Beltz, APHIS, presentation to National Plant Board, 2018 annual meeting).

SPREAD WITHIN THE UNITED STATES

Major pathways for human-assisted spread of pests within the country are sales of plants for planting, movement of unprocessed wood – especially firewood, and hitchhiking on transport vehicles. Since most forest pests are not subject to federal quarantine, any regulatory programs aimed at preventing spread depend on cooperation among the 50 states. None of these pathways is regulated adequately to prevent pests’ spread. See Chapter 5 of Fading Forests III here.

And since neither federal nor state agencies do significant enforcement of existing regulations, preventing spread often depends upon pest awareness of, and voluntary compliance by, individuals and companies.

Even pests subject to a federal quarantine are not prevented from spreading. Plants exposed to the sudden oak death pathogen were shipped to 18 states in spring 2019.

SOD-infected rhododendron plant; Indiana Department of Natural Resources

A collaborative effort by the nursery industry, APHIS, and states (Systems Approach to Nursery Certification, or SANC) is striving to close gaps linked to the standard practice of inspecting plants at the time of shipping, but full implementation of this voluntary program is still years away.

Transport of firewood has been responsible for movement of pests both short distances, e.g., goldspotted oak borer in southern California; and long distances – e.g., emerald ash borer to Colorado. APHIS attempted to develop a certification program but the industry was unable to put one together (see Chapter 5 of Fading Forests III). Current federal and state regulations of firewood are tied to the emerald ash borer quarantine, which APHIS has proposed to terminate. Wood for turning and woodworking has also been linked to movement of pests, e.g., walnut twig beetle/thousand cankers disease from the west to Pennsylvania.

emerald ash borer

Truck transport of a variety of goods has transported European gypsy moths from the infested areas in the east to the west coast. Transport of stone probably moved spotted lanternfly from southeastern Pennsylvania to Winchester, Virginia.

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