Author: phytodoer@aol.com

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

Cerambycid larva detected in wood packaging
photo by Oregon Department of Agriculture

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?

pallet “graveyard” – Photo by Anand Prasad, Davey Tree

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.

SOD – questions that need answers

SOD in the nurseries

infected rhododendron
photo by Jennifer Parke
Oregon State University

As you may remember, in May 2019, we became aware of a troubling outbreak of the sudden oak death pathogen Phytophtora ramorum in the nursery trade. The discovery was made by Indiana authorities, who carefully inspected plants being sold in the state.

Briefly, 28 states initially learned that they might have received plants from the suspect sources. Later, APHIS determined that plants exposed to the pathogen had been sent to 18 states – Alabama, Arkansas, Iowa, Illinois, Indiana, Kansas, Kentucky, Michigan, Missouri, Nebraska, North Carolina, Ohio, Oklahoma, Pennsylvania, Tennessee, Texas, Virginia, and West Virginia. Of these, seven (Iowa, Illinois. Indiana, Kansas, Missouri, Nebraska, Oklahoma) plus Washington were known to have received P. ramorum-positive nursery stock. [California Oak Mortality Task Force Newsletter August 2019]

The 2019 episode was just the latest of several occasions since 2004 in which infected plants have been widely distributed by the nursery trade, despite federal and state regulations.

APHIS delays in explaining the situation and what actions it was taking led the states to complain through a letter from the National Plant Board.

For discussions of the 2019 espisode, see my earlier blog or the California Oak Mortality Task Force newsletter for February 2020.

What have we learned from this episode?

1) Three West coast states – California, Oregon, and Washington – are a usual source for the nursery trade of plant taxa that happen to host the P. ramorum pathogen plants. These states’ climates are conducive to growth of these plants and of the pathogen. After repeated nursery outbreaks over 16 years, I think it is time to question continued reliance on such a high-risk source for these plants.

2) APHIS funds the federally-mandated inspection programs in the three states through the “specialty crops” line of the agency’s annual appropriations. Funding levels have apparently remained steady in recent years (COMTF Feb 2020), despite increases in the overall funding for the “specialty crops” line in recent years. I – and some of you! – have lobbied for these increases precisely in order to address the P. ramorum threat. Why has the funding not been increased?

3) While APHIS allocated $352,945 (COMTF February 2020) from the Plant Pest and Disease Management and Disaster Prevention program to help states carry out nursery surveys in 14 states following the 2019 incident, some of the affected states were not included in the program and some states that had not received suspect plants were. States that did not get funding in Fiscal Year 2020 (2020 award report) included three where P. ramorum-positive plants were detected: Iowa, Illinois, and Indiana; and one state that had a scare – Pennsylvania received plants but none tested positive. Seven states received P. ramorum survey funds through the Plant Pest and Disease Management and Disaster Prevention program although they had not received positive plants in the 2019 incident. These were Maryland, Massachusetts, Nevada, New York, North Dakota, Rhode Island, and South Carolina.

The Plant Pest and Disease Management and Disaster Prevention program distributes $70 million annually, and is not subject to annual appropriations. Does a national crisis play any role in determining which projects get funded? Or are decisions made entirely on a proposal by proposal basis and so depend on states’ priorities and individuals’ grant-writing skills?

4) Even now, on the verge of a new plant shipping season (if one occurs given the Covid-19 virus shutdowns), I have seen no public information clarifying how the inspection systems in Washington, British Columbia, and at the U.S. border failed to detect the infested plants before they were shipped. Trace-back efforts carried out by state and U.S. authorities pointed to a nursery in British Columbia as the original source of the infested plants. However, the Canadian Food Inspection Service (CFIA) determined that no Canadian nursery shipped infected plants to the U.S. in 2018 or 2019. See the next paragraph for a description of APHIS’ efforts to resolve this discrepancy.

According to information in the Oregon Department of Agriculture report for 2019, plant imports from Canada are inspected by DHS Customs and Border Protection (CBP) agriculture specialists, not by APHIS. Apparently, CBP has been relying on rules applicable to fruits and vegetables (Q-56) rather than the more stringent provisions of the plants for planting regulation (Q-37). Alerted by Oregon to the importation of 15 Euonymus plants infested by a federally-designated quarantine pest (a thrips), the National Plant Board sent a letter to APHIS in August 2019 asking that it correct CBP’s inspection process.

In March 2020, APHIS sent a letter to the states saying it had amended its Manual and guidance to CBP agricultural inspectors to clarify that all plants for planting must be handled in accordance with the more stringent Q-37 regulations. Furthermore, APHIS is working with CFIA to clarify understanding of each other’s P. ramorum procedures. The letter states that APHIS might consider prohibiting importation of P. ramorum hosts from Canada until CFIA demonstrates that it has adopted effective management measures.

This action by APHIS demonstrates a new seriousness in addressing P. ramorum. I hope this gravitas will persist and carry through to 1) strengthening theregulatory conditions governing domestic production and sales see following section); 2) providing financial and other support to the states (see above about the “specialty crops” appropriation); 3) funding additional studies to clarify the host list and modes of transmission; and 4) using its authority under NAPPRA to curtail imports of plants from Vietnam and other areas where there are large numbers of newly detected Phytophthora species that might threaten North American plant species.  

infested plants detected by Indiana inspectors

I question sufficiency of inspection and mitigation regime

(as described in the February 2020 COMTF newsletter)

When alerted to the infected plants turning up in Indiana, in May 2019, Washington State Department of Agriculture (WSDA) began trace-back investigations. The large wholesale shipping nursery that supplied the plants appears to have acted quite responsibly – it destroy 54,000 plants, cooperated in the Critical Control Point assessment, and implemented mitigation actions. However, I am disturbed to read that the destruction of plants in the 10-meter quarantine radius from plants detected to be infected was a voluntary action. Why don’t the regulations require destruction of nearby hosts?

Descriptions of the western states’ inspection systems – those tied to this specific nursery episode and routine inspections under federal and state P. ramorum programs – indicate to me that P. ramorum is circulating in nurseries in the west coast states, but is evading detection. I cite examples from all three states.

One of the positive nurseries in California in 2019 had been found to be positive in previous years and is considered to be in compliance with quarantine regulations. Yet these measures have not been sufficient to ensure that the nursery is pathogen-free now – as illustrated by its testing positive in 2019.

In Oregon, a retail nursery found to have infected plants destroyed all host material located in the block. Is this action sufficient to ensure that the nursery is now pathogen free? What about the soil, water, cull piles, etc.?  Oregon trace-back surveys led to various suppliers that had previously not been known to be infested. This leads me to think that the pathogen is circulating below regulators’ attention.

In the wake of the 2019 crisis, Washington State Department of Agriculture (WSSA) inspected “opt-out” nurseries – those that had decided not to join APHIS’ program to ship interstate, but continued to ship within the state. WSDA relied on visual inspection only of host material; the agency collected no samples from plants or nursery soils, water, or plant waste (Feb 2020 COMTF). Given all we know about the difficulty of detecting P. ramorum, I think we need more intense inspections that do sample soils, water, and any nearby plant waste (cull piles).

Meaning of Stream Detections?

The P. ramorum pathogen continues to turn up regularly in water bodies. At a botanical garden in Washington State, plant samples have been negative since February 2016. However, water baits from a small pond were positive in 2019 and previous years. Washington’s Sammamish Riverhas been positive since 2007. In the Southeast, seven streams tested positive in 2019. Most if not all have been positive consistently or at least repeatedly for years. All these positive streams are associated with nurseries previously positive for the pathogen. However, plants in the vicinities of these streams show no symptoms.

The same is true in Vietnam: P. ramorum was found in seven out of eight high-elevation streams sampled, but none of the plants belonging to families that have proved highly vulnerable in North America and Europe had any disease symptoms (Jung et al, 2020. A Survey in Natural Forest Ecosystems of Vietnam Reveals High Diversity of both New and Described Phytophthora Taxa including P. ramorum. Forests, 2020, 11). The Jung et al. 2020 findings are discussed in the COMTF Feb. 2020 newsletter and my recent blog.

SOD in the woods

dead coast live oak in California
Joseph O’Brien, USFS

The COMTF February 2020 newsletter summarizes the worrying increase in disease in California woodlands in recent years, which followed the record wet spring of 2017. Aerial surveys documented a big increase in dead tanoak trees and affected acreages in 2018, followed by a smaller increase in 2019 – although still much higher than in 2017. [Details: in 2017, 21,000 dead trees were mapped across 18,000 acres; in 2018, 1.6 million dead trees across 106,000 acres; in 2019, 885,000 dead trees across 92,000 acres.]

California officially records as infested only those counties where infestations have been confirmed by California Department of Food and Agriculture or county Agricultural Commissioners. California currently lists 15 counties as infested. Recent observations by academics or other non-officials of Phytophthora ramorum in Del Norte and San Luis Obispo counties have not yet been confirmed by officials so neither is included in the official quarantine. I understand the need to be certain about reported detections, but we should remember that the disease is probably more widespread than official data indicate.

The newsletter reports Oregon’s treatment efforts – which have totaled 7,300 acres since 2001. I am pleased that Oregon Department of Forestry now has an Environmental Quality Incentives Program (EQIP) project with the USDA Natural Resources Conservation Service and that both the Bureau of Land Management and USDA Forest Service are treating infected areas.

treatment of SOD-infested site
in Oregon
USFS

Still, the quarantine area now covers 31% of Curry County, the EU1 lineage is established in the forest, and ODF and its partners lack sufficient resources to treat all infected areas.

Washington State doesn’t have (known) forest infestations, but it continues to find the pathogen in water bodies; the Sammamish River in King County has been positive since 2007.

In the East, seven states (Alabama, Florida, Georgia, Mississippi, North Carolina, South Carolina, and Texas) participated in the USFS Cooperative Sudden Oak Death Early Detection Stream Survey in 2019. A total of 48 streams were surveyed. P. ramorum was detected from seven streams – five in Alabama, one in Mississippi, and one in North Carolina. All positive streams were associated with nurseries previously positive for the pathogen.

Finally, the newsletter summarizes an article providing advice on managing SOD’s impacts – specifically, conservation of tanoak.

SOURCES

February 2020 issue of the California Oak Mortality Task Force newsletter http://www.suddenoakdeath.org/wp-content/uploads/2020/02/COMTF-Report-February.pdf

Oregon Department of Agriculture Plant Protection and Conservation 2019 annual report

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.

Hope for eastern hemlocks – IF funding can be obtained

eastern hemlocks in Great Smoky Mountains National Park

As we all know, eastern (Tsuga canadensis) and Carolina (T. caroliniana) hemlocks have suffered huge losses due primarily to the introduced hemlock woolly adelgid (Adelges tsugae – HWA). In New England, there has been more than a 60% decrease in total hemlock basal area since 1997 and a virtual absence of hemlock regeneration in HWA-infested areas. HWA continues to spread – most recently into western Michigan and Nova Scotia (all information, unless otherwise indicated, is from Kinahan et al. 2020; full citation at end of this blog). [However, Morin and Liebhold (2015) found that hemlock basal volume continued to increase for the first 20 years or so after invasion by the adelgid, due to ingrowth of immature hemlocks. See “results” in Morin et al., full citation at the end of the blog.]

This loss deprives us of a gorgeous tree … and unique habitats. Hemlock-dominated forests were characterized by deep shade, acidic and slowly decomposing soil, and a cool microclimate. They provided unique and critical habitat for many terrestrial and aquatic species.

A team of scientists based at the University of Rhode Island has carried out an experiment comparing cuttings from eastern hemlocks apparently resistant to HWA to susceptible ones. Matching sets of resistant and susceptible trees were planted at eight sites in seven states – Ithaca and Bronx, NY; Boston; southern CT; Lycoming County, PA; Thurmont, MD; southern WV; and Waynesville, NC. All plantings were within or adjacent to forests containing HWA-infested hemlocks.

After four years, 96% of the HWA-resistant hemlocks had survived, compared to 48% of the control plants. The HWA-resistant plants were 32% taller, put out 18% more lateral growth, had 20% longer drip lines, and were in 58% better condition. HWA was found on trees at only three out of the eight plots. HWA density on resistant eastern hemlocks was 35% lower than on HWA-susceptible hemlocks, although this difference was not statistically significant.

Trees in all eight plots were infested with elongate hemlock scale (Fiorinia externa – EHS), a second insect damaging hemlocks in eastern North America. However, the HWA-resistant hemlocks had EHS densities 60% lower than those of the controls.

Kinahan et al. note that identification and use of host tree populations’ potential for pest resistance has played a role in other programs managing non-native pests and pathogens, including Dutch elm disease and chestnut blight.  

The same scientists note that significant effort has been put into biocontrol or insecticides for management of hemlock woolly adelgid, but without achieving the desired improvement of forest health. Attempts to cross eastern hemlocks with HWA-resistant hemlocks unfortunately produced no viable offspring. However, Kinahan et al. were inspired to explore possible genetic resistance within natural populations of eastern hemlocks by the 1) evidence of resistance in Asian and western hemlocks; 2) the different foliar terpene profiles in those species; and 3) the presence of apparently healthy mature hemlock trees growing in proximity to heavily infested trees.

They asked forest managers and other concerned groups to help locate stands with trees that were mature and apparently completely healthy, were located within HWA-devastated hemlock stands, and had not been chemically treated. They chose a small stand of eastern hemlocks growing within the Walpack Fish and Wildlife Management Area in northern New Jersey. This stand was called the “Bulletproof Stand”. They evaluated HWA resistance in five of these trees, then chose two for propagation and planting in the test.

New Jersey’s “bullet-proof stand” on the left
photo by Richard Casagrande

The trees were planted in September 2015. Due to funding gaps, they were not revisited for four years. Thus, Kinahan et al. re-evaluated the resistant and vulnerable trees in Autumn 2019 – with the results I reported above.

Does this study prove that clonal propagation of apparently resistant hemlocks is an effective strategy to restore the species?

It is not that simple.

The difference in survival and condition was striking, but the authors note several caveats:

1) they had not recorded pre-experiment data on plant height or other variables, so they cannot be certain that variation in initial plant height or dripline did not contribute to current treatment-level differences in these variables.

2) they cannot distinguish between the impacts of HWA and EHS on plant growth.

3) since they could not monitor the planting sites for four years, they cannot definitively link increased mortality of HWA-susceptible trees to higher pest densities. However, the lower pest densities and higher survival of HWA-resistant hemlocks are consistent with herbivore-driven tree mortality.

They also cannot assess the impact of other environmental stressors (drought, cold, etc.) on their results.

4) The small number of trees planted at each site prevented detailed site-level analyses.

The scientists conclude that their work is most appropriately viewed as a ‘proof of concept’ experiment highlighting the need for future research exploring how HWA-resistant eastern hemlocks might best be integrated into existing HWA management.

Unfortunately, the Rhode Island researchers report they cannot persuade the US Forest Service to support continuing this effort. Will these promising hints not result in action?

Kinahan et al. stress the importance of the reduced pest densities (both HWA and EHS) on the putatively resistant hemlocks. They think this might be a result of the higher terpene concentrations in the twigs and needles. Finally, they note that lower densities of sap-feeding herbivores may also indirectly provide protection against other consumers, including gypsy moth (Lymantria dispar) and hemlock looper (Lambdina fiscellaria).

SOURCE

Kinahan, I.G., G. Grandstaff, A. Russell, C.M. Rigsby, R.A. Casagrande, and E. L. Preisser. 2020. A four-year, seven-state reforestation trial with eastern hemlocks (Tsuga canadensis) resistant to hemlock woolly adelgid (Adelges tsugae). Forests 11: 312

Morin, R.S. and A.M. Liebhold. 2015. Invasions by two non-native insects alter regional forest species composition and successional trajectories. Forest Ecology and Management 341 (2015).

Posted by Faith Campbell

P.S. I have been working with colleagues to promote a more coordinated and well-funded program to combat non-native forest pests – including much greater reliance on identifying and breeding resistance to the pest. Visit here to see this effort.

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.

Another New Pest Detected in California; Possible Threat to Native Shrubs

Rhus integrifolia

The California Department of Food and Agriculture (CDFA) is seeking comments  on the appropriate pest rating for Leptosillia pistaciae, a recently discovered fungus that causes pistachio canker.

The Department’s draft pest ranking assigns the highest Economic Impact score – three. It assigns a medium Environmental Impact – two. This is because the pathogen can kill an important native shrub, with possible follow-on consequences of reduced biodiversity, disrupted natural communities, or changed ecosystem processes.

CDFA states that there is no uncertainty in its evaluation, but I see, and describe here, numerous questions about the possible true extent of the invasion and possible host range.  

Comments are due on April 4, 2020.

The pathogen was detected in June 2019, when a habitat manager from an ecological reserve in San Diego County noticed multiple dead lemonade berry shrubs (Rhus integrifolia) in one of the parks. This is the first known detection of Leptosillia pistaciae in the United States and on this host. USDA APHIS has classified Leptosillia pistaciae as a federal quarantine pest. Rhus and Pistacia are in the same family, Anacardiaceae (cashews and sumacs).

According to the CDFA, Leptosillia pistaciae is the only member of this fungal genus known to be associated with disease symptoms on plants. Other species are endophytes or found in dead plant tissues. [It is not at all unusual for fungal species to be endophytes on some plant hosts but pathogenic on others. A California example is Gibberella circinata (anamorph Fusarium circinatum), which causes pitch canker on Monterey pine (Pinus radiata) but is an endophyte on various grass species (Holcus lanatus and Festuca arundinacea).]

(Reminder: this is the second new pest of native species detected in California state in 2019; I blogged about an ambrosia beetle in Napa County here. )

Rhus integrifolia (lemonade berry or lemonade sumac) is native to California. It grows primarily in the south, along the coast – from San Diego to San Luis Obispo. However, some populations are also found in the San Francisco Bay area. This and other sumacs are also sold in the nursery trade.

On pistachio trees in Italy, symptoms are observed in the winter and late spring. During the winter dormant season, trees had gum exudation and cracking and peeling of bark on trunks and branches. On trunks and large branches, cankers appeared first as light, dead circular areas in the bark; subsequently they became darker and sunken. Under the bark, cankers were discolored with necrotic tissues; in some cases, these extended to the vascular tissues and pith. During the active growing season, the symptomatic plants also showed canopy decline. Inflorescences and shoots, originating from infected branches or twigs, wilted and died. When the trunk was girdled by a canker, a collapse of the entire tree occurred.

range map for Rhus integrifolia

On lemonade berry, large clumps of dead adult shrubs were observed on the edge of hiking trails. Some shrubs that had completely dead foliage were re-sprouting from their bases. Trunks of shrubs that were not completely dead were copiously weeping sap and fluids and showed foliage browning and die back with symptoms of stress.

It is thought that spores could be spread by wind, rain splashing, and the movement of dead or dying trees, greenwaste, and infected nursery stock. Contaminated pruning tools might also transport the spores. The possibility of a latent phase – or perhaps asymptomatic hosts – adds to the probability of anthropomorphically assisted spread.

I question how much effort has been put into detection surveys, especially in natural systems with native Rhus species. California has three other native sumacs: R. ovata, R. aromatica, and Malosma laurina (CNPS; full citation at the end of the blog). In addition, there are numerous other species in the family, including poison oaks (Toxicodendron spp.) and the widespread invasive plant genus Schinus.

Furthermore, some plants in the family (other than pistachios) are grown for fruit or in ornamental horticulture, including two of the native sumacs and two non-native species, Rhus glabra and R. lanceolata, cashew, mango, and smoke trees (Cotinus spp.).

Yet CDFA confidently states that there are only two hosts and that it has been detected in only one population – that in San Diego. This is because CDFA considers only official records identified by a taxonomic expert and supported by voucher specimens.

CDFA states that the pathogen is likely to survive in all parts of the state where pistachios are grown – primarily in the Central Valley. California supplies 98% of the pistachios grown in the United States; the remainder is raised in Arizona and New Mexico. California production occurred on 178,000 acres in 2012. A map is included in a flyer on production available at the url listed at the end of this blog.

In discussing spread potential, no mention is made of possible human-assisted spread.

The CDFA document includes instructions for submitting comments; the deadline is April 4.

Sources:

Rhus and related species native to California: California Native Plant Society

https://calscape.org/loc-california/Rhus(all)/vw-list/np-1?

Rhus species used in horticultural plantings in California: CalFlora https://www.calflora.org//cgi-bin/specieslist.cgi?where-genus=Rhus 

Pistachio production information: https://apps1.cdfa.ca.gov/FertilizerResearch/docs/Pistachio_Production_CA.pdf

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.

Progress – Now Threatened – On Protecting Our Cacti

prickly pear cacti in Big Bend National Park
photo by Blake Trester, National Park Service

The cacti that are such important components of desert ecosystems across nearly 2 million square miles straddling the U.S.-Mexico border are under threat from non-native insects – as I have noted in earlier blogs. Of course, cacti are important in other ecoregions, too – I wrote recently about the columnar cacti in the dry forests of Puerto Rico.

Flat-padded prickly pear cacti of the genus Opuntia are threatened by the cactus moth, Cactoblastis cactorum.

In 1989, the cactus moth was found in southern Florida, to which it had spread from the Caribbean islands (Simonson 2005). Recently, the moth was found to have spread west as far as the Galveston, Texas, area and near I-10 in Columbus, Texas, about 75 miles west of central Houston (Stephen Hight, pers. com.) Two small outbreaks on islands off Mexico’s Caribbean coast have been eradicated.

In Florida, the cactus moth has caused considerable harm to six native species of prickly pear, three of which are listed by the state as threatened or endangered.

When the cactus moth reaches the more arid regions of Texas, it is likely to spread throughout the desert Southwest and into Mexico. In the American southwest, 31 Opuntia species are at risk; nine of them are endemic, one is endangered. Mexico is the center of endemism for the Opuntia genus. In Mexico, 54 Opuntia species are at risk, 38 of which are endemic (Varone et al. 2019; full citation at end of this blog).

The long-term effects of the cactus moth on these North American Opuntia are unknown because there may be substantial variations in tolerance. The attacks observed in the Caribbean islands have shown great variability in various cactus species’ vulnerability (Varone et al. 2019).

The Opuntia cacti support a diversity of pollinators as well as deer, javalina (peccaries), tortoises, and lizards. Prickly pears also shelter packrats and nesting birds (which in turn are fed on by raptors, coyotes, and snakes), and plant seedlings. Their roots hold highly erodible soils in place (Simonson 2005).

While scientists have been concerned about the possible impacts of the cactus moth since it was detected in Florida 30 years ago, a substantial response began only 15 years later. The U.S. Department of Agriculture began trying to slow the spread of the cactus moth in 2005 (Mengoni Goñalons et al. 2014), with a focus on surveys and monitoring, host (cactus) removal, and release of sterile males. This program was successful at slowing the moth’s spread and eradicating small outbreaks on offshore islands of Alabama, Mississippi, and Mexico.

Cactus moth damage to native cacti in Florida
photo by Christine Miller, UF/IFAS

However, the moth continued to spread west and the program never received an appropriation from Congress. The primary funding source was a US – Mexico Bi-National Invasive Cactus Moth Abatement Program. Both countries contributed funds to support the research and operational program to slow the spread in the U.S. Funds were provided through USDA Animal and Plant Health and Inspection Service (APHIS) and the Mexican Secretariat of Agriculture, Livestock, Rural Development, Fisheries and Food (SEGARPA). Unfortunately, funding was reduced by both entities and became inadequate to maintain the Bi-National Program.

Therefore, in 2012, APHIS abandoned its regional program and shifted the focus to biocontrol. This is now considered the only viable control measure in the desert Southwest where vulnerable cacti are numerous and grow close together. The biocontrol project has been funded since 2012 through the Plant Pest and Disease Management and Disaster Prevention program (which receives funding through the Farm Bill). It has received a total of slightly more than $2 million over seven years. More than half the funds went to the quarantine facility to support efforts to rear non-target hosts and verify the biocontrol agent’s host specificity. About a quarter of the funds supported complementary work of an Argentine team (both the cactus moth and the most promising biocontrol agent are native to Argentina). Much smaller amounts have supported U.S.-based scientists who have studied other aspects of the cactus moth’s behavior and collected and identified the U.S. moths being tested for their possible vulnerability to attack by a biocontrol wasp.

Here are details of what these dedicated scientists achieved in just the past seven years at the relatively low cost of roughly $2 million. Unfortunately, the project now faces a funding crisis and we need to ensure they have the resources to finish their work.

Some Specifics of the BioControl Program

After literature reviews, extensive collections, and studies in the cactus moth’s native habitat in Argentina (Varone et al. 2015), a newly described wasp, Apanteles opuntiarum (Mengoni Goñalons et al. 2014), has been determined to be host specific on Argentine Cactoblastis species and the most promising candidate for biocontrol. Wasps were collected in Argentina and sent to establish a colony in a quarantine facility in Florida to enable host specificity studies on North American Lepidoptera (Varone et al. 2015).

Quarantine host specificity studies and development of rearing technology has not been straightforward. Initially, it was difficult to achieve a balanced male/female ratio in the laboratory-bred generations; this balance is required to maintain stable quarantine laboratory colonies for host range testing. This difficulty was overcome. A second challenge was high mortality of the cactus-feeding insects collected in the Southwest that were to be test for vulnerability to the biocontrol wasp. These desert-dwellers don’t do well in the humid, air-conditioned climate of the quarantine facility! For these difficult-to-rear native insects, scientists developed a molecular genetics method to detect whether eggs or larvae of the cactus moth parasitoid were present inside test caterpillars after they were exposed to the wasps. For easy to rear test insects, caterpillars are exposed to the wasps and reared to adulthood. Host specificity tests have been conducted on at least five species of native U.S. cactus-feeding caterpillars and 11 species of non-cactus-feeding caterpillars (Srivastava  et al. 2019; Hight pers.comm.).

To date there has been no instance of parasitism by Apanteles opuntiarum on either lepidopteran non-target species or non-cactus-feeding insects in the Florida quarantine or in field collections in Argentina (Srivastava et al. 2019; Varone et al. 2015; Hight pers.comm.).

The scientists expected to complete host-specificity testing in the coming months, then submit a petition to APHIS requesting the release of the wasp as a biocontrol agent. Unfortunately, the project’s request for about $250,000 in the current year was not funded. This money would have funded completion of the host specificity testing, preparation of a petition to APHIS in support of release of the biocontrol agent into the environment, and preparation of the release plan.

Meanwhile, what can we expect regarding the probable efficacy of the anticipated biocontrol program?

Some of the wasp’s behavioral traits are encouraging. The wasp is widely present in the range of the cactus moth, and persisted in these areas over the years of the study. The wasp can deposit multiple eggs with each “sting”. Multiple wasps can oviposit into each cactus moth without detriment to the wasp offspring. Unmated wasp females produce male offspring only, whereas mated females produce mixed offspring genders. In the field, female wasps attack cactus moth larvae in a variety of scenarios: they wait at plant access holes to sting larvae when they come outside to defecate; they attack larvae when they are moving on the surface of the pads; they can sting the youngest cactus moth larvae through the thin plant wall of mined the pads; and they enter large access holes created by older larvae and attack larger larvae. The wasps are attracted by the frass (excrement) left on the outside of the cactus pads by cactus moth larvae (Varone et al. 2020).

However, I wonder about the extent to which the cactus moth is controlled by parasitoids in Argentina. Cactoblastis eggs are killed primarily by being dislodged during weather events (rain and wind) and by predation by ants. First instar larvae are killed primarily by the native Argentine cactus plants’ own defenses – thick cuticles and release of sticky mucilage when the young larvae chew holes into the pads where they enter and feed internally. As larvae feed and develop inside the pads, the primary cause of mortality is natural enemies.

Of all the parasitoid species that attack C. cactorum, A. opuntiarum is the most abundant and important. When the larvae reach their final state (6th instars), they leave the pads and find pupation sites in plant litter near the base of the plants. It is at this stage that the parasitism from A. opuntiarum is detected in the younger larvae that were attacked while feeding inside pads. As the moth larva begins to spin silk into which to pupate, larvae of the wasp erupt through the skin of the caterpillar and pupate within the silk spun by the moth. Predation by generalists (ants, spiders, predatory beetles) accounted for high mortality of the unprotected last instar and pupae (Varone et al. 2019).

Finally, the cactus moth has three generations per year when feeding on O. stricta in the subtropical and tropical coastal areas of the Americas and the Caribbean. In Argentina, on its native host, the moth completes only two generations per year (Varone et al. 2019).

 How to Get the Program Support Needed

Opuntia in Big Bend National Park
Photo by Cookie Ballou,
National Park Service

To date, no organized constituency has advocated for protection of our cacti from non-native insect pests. Perhaps now that the Cactoblastis moth is in Texas, the threat it represents to our desert ecosystems will become real to conservationists and they will join the struggle. The first step is to resolve the funding crisis so that the agencies can complete testing of the biocontrol agent and gain approval for its release. So now there is “something people can do” – and I hope they will step forward.

I hope Americans are not actually indifferent to the threat that many cacti in our deserts will be killed by non-native insects. Many are key components of the ecosystems within premier National Parks, and other protected areas. Cacti also are beautiful treasures in botanical gardens. I hope conservationists will agree that these threats must be countered, and will help to ensure funding of the final stages of the biocontrol tests.

Sources

Mengoni Goñalons, C., L. Varone, G. Logarzo, M. Guala, M. Rodriguero, S.D. Hight, and J.E. Carpenter. 2014. Geographical range & lab studies on Apanteles opuntiarum (hymenoptera: braconiDae) in AR, a candidate for BC of Cactoblastis cactorum (Lepidoptera: Pyralidae) in North America. Florida Entomologist 97(4) December 2014

Simonson, S.E., T. J. Stohlgren, L. Tyler, W. Gregg, R. Muir, and L. Garrett. 2005. Preliminary assessment of the potential impacts and risks of the invasive cactus moth, Cactoblastis cactorum Berg, in the U.S. and Mexico. Final Report to the International Atomic Energy Agency, April 25, 2005 © IAEA 2005

Srivastava, M., P. Srivastava,  R. Karan, A. Jeyaprakash, L. Whilby, E. Rohrig, A.C. Howe,  S.D. Hight, and L. Varone. 2019. Molecular detection method developed to track the koinobiont larval parasitoid Apanteles opuntiarum (Hymenoptera: Braconidae) imported from Argentina to control Cactoblastis cactorum (Lepidoptera: Pyralidae). Florida Entomologist 102(2): 329-335.

Varone, L., C.M. Goñalons, A.C. Faltlhauser, M.E. Guala, D. Wolaver, M. Srivastava, and S.D. Hight. 2020. Effect of rearing Cactoblastis cactorum on an artificial diet on the behavior of Apanteles opuntiarum. Applied Entomology DOI: 10.1111/jen.12731.

Varone, L., G. Logarzo, J.J. Martínez, F. Navarro, J.E. Carpenter, and S.D. Hight. 2015. Field host range of Apanteles opuntiarum (Hymenoptera: Braconidae) in Argentina, a potential biocontrol agent of Cactoblastis cactorum (Lepidoptera: Pyralidae) in North America. Florida Entomologist — Volume 98, No. 2 803

Varone, L., M.B. Aguirre, E. Lobos, D. Ruiz Pérez, S.D. Hight, F. Palottini, M. Guala, G.A. Logarzo. 2019. Causes of mortality at different stages of Cactoblastis cactorum in the native range. BioControl (2019) 64:249–261

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.

2021 Funding: Crisis for USFS, OK for APHIS – Both Need Your Support

As happens every year, the Administration has proposed a budget for funding government programs in the next Fiscal Year (FY) – which begins on October 1, 2020 (FY2021). This proposal is not the final word. Congress will pass appropriations bills that will specify actual funding levels. NOW is the time for you to tell senators and representatives in Congress how much money you think agencies need to count tree-killing pests next year.

Pest programs most affected:

  • Sudden oak death (SOD):
  • Combination of goldspotted oak borer, laurel wilt, and thousand cankers disease
  • Port-Orford cedar root disease
  • Threats to whitebark pines
  • emerald ash borer

USDA Forest Service (USFS)

For the USFS, the Administration proposes alarming cuts.

Forest and Rangeland Research Program

FY18                           F719                FY20               FY21 proposed

297,000,000                300,000,000    305,000,000    249,330,000

[In FYs 18 – 20, Forest Inventory & Analysis received $77 million of this total; the proposal for FY21 is $78.5 million. Under this proposal, inventory would receive more than 30% of all research funding!]

The Administration proposes to cut USFS R&D overall by 25%. Also, it calls for closing the Pacific Southwest Research Station in California.

These proposed cuts would come on top of severe reductions over the past decade. Although the appropriation does not provide specific spending figures for invasive species, funding for research conducted by the seven research stations on ten non-native pests decreased from $10 million in FY2010 to just $2.5 million in FY2020 – a cut of more than 70%. The Service’s ability to develop effective tools to manage the growing number of pests threatening the health of the Nation’s forests is already crippled by the earlier cuts.

The proposal to close the Pacific Southwest Research Station is particularly unwise. This Station provides USFS’s crucially important expertise on both sudden oak death (SOD) and threats to Hawaiian forests, including rapid ʻōhiʻa death (ROD). These pathogens are already causing widespread and severe damage to forests in the region and leading experts work here.

USFS R&D must address two new threats associated with sudden oak death:

  1. need to better understand the possible impacts of the second, apparently more aggressive, genetic strain of the SOD pathogen now present in Oregon’s forests.
  2. studies to determine which of the newly detected Phytophthora species found in Southeast Asia Link to blog and other regions might cause significant damage to America’s trees.  

Other programs that USFS R&D should continue or expand:

  • study the possible threat posed by the ambrosia beetle recently detected in Napa Valley of California.
  • understand the epidemiology and probable impacts of the recently detected beech leaf disease present from Ohio to Connecticut and possibly more widespread.

Forest Health Management Programs 

Recent funding levels:

FY18                           F719                            FY20               FY21 proposed

96,500,000                  98,000,000                  100,000,000    73,636,000

The Forest Health Management (FHP) Program supports federal agencies’ and partners’ efforts to prevent, monitor, suppress, and eradicate insects, diseases, and invasive plants. The White House proposes a $23 million cut, including a cut of $10 million to programs working on “cooperative lands” – all areas other than federal lands. This proposed cut is short-sighted and worrisome. First, these forests support a wide range of forest values. Second, non-native pests usually are usually first introduced in cities or suburbs – because they accompany imports destined for population centers. These newly arrived pests initially cause enormous damage to urban forests. Counter-measures need to be initiated where and when the pests arrive and their populations are low. We cannot afford to wait for them to spread to national forest lands, when management will be harder and more expensive.

Despite ever-rising numbers of non-native forest pests over the past decade, funding for FHP work on Cooperative Lands has fallen by about 50%. Pest species suffering the largest cuts in recent FHP budgets are the combination of gold spotted oak borer, thousand cankers disease, and laurel wilt; Port-Orford cedar root disease, and threats to whitebark pines.

As I reported in a previous blog, an estimated 41% of forest biomass in the “lower 48” states is at risk from the 15 non-native pest species causing the greatest damage. Nevertheless, the Administration proposes to eliminate programs for several of the most hard-hit host tree species (redbay/laurel wilt, Port-Orford cedar, and whitebark pine) in FY2021. This proposal is contrary to priorities recommended through the CAPTURE project, which called for enhanced conservation efforts targetting these species specifically.

Also alarming is the cut to the informal “emerging pest” account. This valuable program funds projects targetting newly detected threats. Thus, in FY2019, FHP provided $125,000 to evaluate the probable impact of laurel wilt disease on sassafras, an important understory tree that grows throughout most of the Eastern Deciduous Forest. The program provided another $116,000 to support efforts to detect and understand beech leaf disease. Already, cuts in the overall FHP budget have necessitated cutting this valuable account  from $1 million in FY19 to $750,000 in FY20 – and will probably result in additional cuts  in FY21.

The budget proposes to cut funding to counter sudden oak death (SOD) Link to DMF by 15% — on top of a 52% cut since FY2018. SOD has killed an estimated 50 million trees from southern Oregon to central California. Not only does the pathogen continue to spread. Establishment of a second, more aggressive, genetic strain of the pathogen in the Oregon forest threatens to exacerbate the pathogen’s impact.

The forests of Hawai`i are facing their gravest threat ever from a growing number of pests. FHP supported detection/monitoring of the thrips attacking a dry forest tree, naio. There is a continuing need to address threats to Hawaii’s most widespread tree, ʻōhiʻa lehua – which makes up 80% of  native forests –  from the introduced “rapid ʻōhiʻa death” fungi.

Finally, stakeholders will depend on leadership by the FHP program to manage spread of the emerald ash borer if the USDA Animal and Plant Health Inspection Service acts as expected and terminates the program under which it regulates movement of firewood, nursery stock, and other items that spread this pest. California and Oregon and other Western states are at greatest risk.

What You Can Do

Senators and representatives serving on the two Interior Appropriations subcommittees will determine the final funding for USFS programs.  

Please ask them to support $303 million for USFS Research and Development. Since the budget does not specify funding levels to be allocated to non-native insects, pathogens, or other invasive species, ask for “report language” instructing USFS to increase the funding for this vital research area to five percent of the total research budget. Ask them also to support maintaining the Pacific Southwest Research Station.

Also, ask them to support maintaining USFS Forest Health and Management Programs at the FY20 level of $100 million in FY21. Ask them to support $44 million for the “cooperative lands” program.

Members of the House Interior Appropriations subcommittee

  • Betty McCollum, Chair                        MN
  • Chellie Pingree                         ME
  • Derek Kilmer                           WA
  • José Serrano                            NY
  • Mike Quigley                           IL
  • Bonnie Watson Coleman         NJ
  • Brenda Lawrence                     MI
  •  
  • David Joyce, Ranking Member            OH
  • Mike Simpson                          ID
  • Chris Stewart                           UT
  • Mark Amodei                          NV

Members of the Senate Interior Appropriations subcommittee

USDA Animal and Plant Health Inspection Service (APHIS)

Again, while the tree-killing pests are usually introduced first in cities or suburbs, the pests don’t stay there. Instead, they proliferate and spread … eventually threatening forests across the continent.  

APHIS has legal responsibility for preventing such pests’ entry, detecting newly introduced pests, and initiating eradication and containment programs intended to minimize the damage they cause. The risk of new introductions is tied to international trade. In 2017, an estimated 17,650 shipping containers (or 48 per day) infested by wood-boring insects entered the United States. Examples of such introductions include the Asian longhorned beetle, emerald ash borer, and several ambrosia beetles which carry the fungi now killing redbay and sassafras in the East, and sycamore and willow trees southern California. Other pests, such as gypsy moths and spotted lanternflies, are transported here as egg masses attached to hard-sided imports, containers, or ship superstructures. Yet more forest pests are brought here with or in imported plants. Two rapid ʻōhiʻa death (ROD) pathogens and beech leaf disease are among newly detected pests probably introduced this way.

APHIS needs to be able to respond to these pests and to the others that will be introduced in coming years. To do so, APHIS must have adequate funding for four programs: “tree and wood pests” program at $60 million; “specialty crops” program at $192 millon; “methods development” at $28 million; and “detection” at $21 million.

The “Tree and Wood Pests” account currently supports eradication and control efforts targeting only three insects: the Asian longhorned beetle (ALB), emerald ash borer (EAB), and gypsy moth. The program to eradicate the ALB has received about two-thirds of the funds — $40 million. It has succeeded in eradicating 85% of the infestation in New York and some of the outlying infestations in Ohio. There is encouraging progress in Massachusetts, although at least one infested tree was detected recently in a new town within the quarantine zone. Clearly, this program must be maintained until final success is achieved everywhere.

The EAB program has been funded at $7 million in recent years. APHIS has proposed to terminate the EAB regulatory program. Program termination would greatly increase the risk that the EAB will spread to the mountain and Pacific coast states, where both riparian woodlands and urban forests would be severely damaged. Many stakeholders have urged APHIS to continue to regulate movement of firewood and other materials that facilitate the EAB’s spread.

The “Specialty Crops” program funds for APHIS’ regulation of nursery operations to prevent spread of the sudden oak death pathogen. Were SOD to become established in the East, it would threaten several oak species, sugar maple, and black walnut. It is therefore alarming that in 2019, plants infected by the SOD pathogen were shipped to 18 states. link to blog APHIS must step up its regulatory efforts to prevent a repetition of this disaster.

What You Can Do

Members of the Senate and House Agriculture Appropriations Subcommittees will set  final funding levels for APHIS programs. Ask your members of Congressto support maintaining the FY2020 funding levels for four APHIS programs: Tree and Wood Pests, Specialty Crops, Methods Development, and “Detection Funding”.

Also, ask them to adopt report language urging APHIS to continue regulating the EAB’s spread. 

Members of the House Agriculture Appropriations subcommittee

  • Sanford Bishop Jr., Chairman              GA
  • Rosa DeLauro                                      CT
  • Chellie Pingree                                     ME
  • Mark Pocan                                         WI
  • Barbara Lee                                         Calif 13th (Oakland)
  • Betty McCollum                                  MN
  • Henry Cuellar                                      TX
  •  
  • Jeff Fortenberry, Ranking Member      NE
  • Robert Aderholt                                               AL
  • Andy Harris                                         MD
  • John Moolenaar                                               MI

Members of the Senate Agriculture Appropriations subcommittee

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.

Growing Pathogen Threat from Southeast Asia – US Unprotected

APHIS can protect our native & agricultural plants – but will it?

Imports of large numbers of plants for planting from Southeast Asia represents a significant biosecurity risk for forestry, horticulture, and natural ecosystems in North America and Europe.  This threat is likely to grow unless APHIS takes action under its emergency authorities.

Recent pest introductions and related studies indicate that Southeast Asia is a newly-discovered center of origin for plant pathogens. Places of particular concern are Vietnam, southern Yunnan Province and Hainan Island of China, northern Laos, the eastern Himalayas, and Taiwan. Significant pathogens and associated insects apparently centered in these areas include the sudden oak death pathogen (Phytophthora ramorum) and other Phytophthora species; and several ambrosia beetles and associated fungi, including the laurel wilt fungus (Raffaelea lauricola) and its primary vector (Xyleborus glabratus), and the polyphagous (Euwallacea whitfordiaodendrus) and Kuroshio shot hole borers (Euwallacea kuroshio).

Southeast Asia is attractive to the plant trade because of the region’s high floral diversity, including such sought-after families as Ericaceae (rhododendrons). Indochina has more than 10,350 vascular plant species in 2,256 genera – equaling more than 20% of the world’s plant species (Jung et al. 2019).

Pathogens are notoriously difficult to detect during inspections at the time of shipment. One-time inspections of high volume imports are especially weak and prone to failure.

How do we protect America’s flora?

APHIS could — but has not yet — developed requirements that these countries institute integrated pest management procedures for their exporting nurseries – as provided under amendments to APHIS’ Q-37 regulation and ISPM#36. In any case, it is unlikely that such procedures would minimize the risk because many of the plants that would be imported would probably be wild-collected.

APHIS has – and should use – far more effective means to minimize risk. These are the Federal orders and listing process known as “not authorized for importation pending pest risk assessment” or NAPPRA. If – despite the scientific evidence – APHIS continues to allow high volumes of dangerous imports, the agency should immediately institute new phytosanitary controls to its inspection process. These include relying on risk-based inspection regimes and molecular high-through-put detection tools.

Supporting Material

SOD-killed tanoaks in Big Sur; photo provided by Matteo Garbelotto, UC Berkeley

Phytophthora species

A team of European pathologists, led by Thomas Jung and including Clive Brasier and Joan Webber (see full citation at the end of this blog) surveyed Phytophthora species by sampling rhizosphere soils in 25 natural and semi-natural forest stands, isolations from naturally fallen leaves, and waters in 16 rivers in temperate and subtropical montane and lowland regions of Vietnam during 2016 and 2017.

These studies detected 13 described Phytophthora species, five informally designated taxa, and 21 previously unknown taxa. Detections were made from soil samples taken from 84% of the forest stands and from all rivers.

As I reported in am earlier blog, P. ramorum and P. cinnamomi were among those species detected. Both the A1 and A2 mating types of both P. ramorum and P. cinnamomi co-occurred.

The survey also detected at least 15 species in other genera of oomycetes.

The scientists conclude that most of the 35 forest Phytophthora species detected are native to Vietnam or nearby surrounding areas, attributing species in Phytophthora clades (taxonomically related groups) 2, 5, 6, 7, 8, 9, and 10 as native to Indochina. Different clades were detected in high-elevation vs. lowland rivers, cooler (subtropical) vs. tropical streams, and in soils vs. streams. Given the relatively limited number and diversity of the sampled sites and ecosystem types, it is likely that the true Phytophthora diversity of Vietnam is markedly higher (Jung et al. 2019)  

Worrying diversity of Phytophthora has been detected in other areas of Southeast Asia. A 2013 survey in natural forests and streams of Taiwan detected 10 described species and 17 previously unknown taxa of which 9 were of hybrid origin. In three areas in northern Yunnan, a Chinese province adjacent to northern Vietnam, eight Phytophthora species were isolated from streams running through sclerophyllous oak forests; two were recovered from forest soil samples. In montane forests of the tropical island Hainan, located in the South China Sea close to Vietnam, six Phytophthora species were found (Jung et al. 2019).

These studies are being conducted in the context of scientists discovering numerous new species of Phytophthora in recent decades. Since 1999, the number of described species and informally designated taxa of Phytophthora has tripled. World-renowned experts Clive Brasier anticipates that between 200 and 600 species of Phytophthora are extant in natural ecosystems around the world (Jung et al. 2019).

In the Vietnam survey, P. ramorum was the most widespread species. While genetic studies indicate ancestral connections to the four P. ramorum lineages (genetic strains) introduced to North America or Europe, further studies are under way to clarify these relationships (Jung et al. 2019).

Jung and colleagues found P. cinnamomi to be the most common soilborne Phytophthora species at elevations above 700 m. Two genotypes of the P. cinnamomi A2 mating type are causing epidemics in numerous natural and managed ecosystems worldwide. There was some evidence that the more frost sensitive A2 mating type might be spreading into higher altitudes in Vietnam (Jung et al. 2019).

Most of the Phytophthora species detected in the rhizosphere were not associated with obvious disease symptoms. (The principal exception was the A2 mating type of P. cinnamomi in montane forests in northern Vietnam.) (Jung et al. 2019) This lack of disease greatly reduces the chances of detecting the oomycetes associated with any plants exported from the region – there are no symptoms.

Since southern Yunnan, northern Laos, and the eastern Himalayas belong to the same biogeographic area those areas might also harbor endemic P. ramorum populations. Further surveys are needed to confirm this hypothesis (Jung et al. 2019).

Phytophthora lateralis – causal agent of Port-Orford cedar root rot – also probably originated in the area, specifically Taiwan (Vettraino et al. 2017).

Implications for phytosanitary measures

Many of the native Asian forest Phytophthora species have co-evolved with a variety of tree genera also present in Europe and North America, including Fagaceae, Lauraceae, Aceraceae, Oleaceae, and Pinaceae. Numerous examples demonstrate a strong potential that trees in these families that have not previously been exposed to these Phytophthora species might be highly susceptible. Scientists have begun an extensive host range study of Phytophthora species from Asia and South and Central America. One part of this study found that five Asian Phytophthora species caused significant rot and loss of fine roots and lateral roots in three European species of chestnut and oak (Jung et al. 2019).

Other pathogens

Studies by separate groups of scientists have concluded that several beetle-fungus disease complexes are native to this same region.

Sassafras – photo by David Moynihan

Both the laurel wilt fungus Raffaelea lauricola and its primary vector Xyleborus glabratus probably originated in Southeast Asia; there are probably different strains or genetic makeups across their wide ranges. For example, Dreaden et al. 2019 found that the fungus population from Myanmar differed genetically from those found in Japan, Taiwan, and the United States. Others had already expressed concern about the possibility that new strains of R. lauricola might be introduced (Wuest et al. 2017, cited in Cognato et al. 2019).

Cognato et al. 2019 found that the beetle occurs in deciduous forests from southern Japan to Northeast India, so genetic variation across this range is likely. In fact, they have separated the species X. glabratus into three species. They found that some of the beetles might thrive at 40o North – the latitude of central Illinois, Indiana, and Ohio and southern Pennsylvania. The ability of the vector of laurel wilt disease to spread so far north poses an alarming threat to sassafras (Sassafras albidum) – which is a major understory tree in forests of these regions.

It is unknown whether these new species and X. glabratus lineages are associated with different fungal strains. In company with the pathologists cited above, Cognato et al. 2019 warn that preventing introduction of the three beetle species to other regions is prudent. Cognato et al. 2019 point out that if other beetle lineages from the southern extent of their range can tolerate hotter and drier conditions, they might pose a greater risk to host species in the more arid areas of California and Mexico. In addition, Central America is at great risk because of the numerous plant species in the vulnerable Lauraceae found there.

Also from the region are two beetle-fungus combinations killing trees in at least seven botanical families, including maples, oaks, and willows, in southern California. The polyphagous shot hole borer (Euwallacea whitfordiaodendrus) apparently is native to Vietnam (Eskalen et al. 2013) and the closely related Kuroshio shot hole borer (Euwallacea kuroshio) to Japan, Indonesia, and Taiwan (Gomez et al. 2018).  

What you can do

Getting APHIS to act

1) communicate concern about the risk to APHIS leadership and ask that the agency take action under its NAPPRA authority

2) communicate the same to intermediaries who can influence APHIS:

  • State phytosanitary agency – especially through regional plant boards and National Plant Board
  • Your Congressional representative and senators (especially if one or more serves on Agriculture or Appropriations committee)
  • Professional societies – American Phytophathological Society, Mycological Society, American Society of Entomologists, Society of American Foresters …

3) communicate the same to university leadership and ask that their lobbyists advocate to USDA

4) communicate the same to the media

2) Research on extent of North American tree species’ vulnerability to the Oomycetes and other associated microorganisms

Jung et al. 2019 say that studies are under way to identify potential pest-host relationships with important tree species. However, all the authors are Europeans. Is anyone carrying out tests on North American trees in the apparently most vulnerable families — Fagaceae, Lauraceae, Aceraceae, Oleaceae, and Pinaceae?

1) Communicate with colleagues, scientific societies, APHIS, Agriculture Research Service, National Institute of Food and Agriculture, and USFS to determine whether such tests are under way or planned.

2) In those cases where no studies are planned, work with above to initiate them.

Sources

Cognato, A.I., SM. Smith, Y. Li, T.H. Pham, and J. Hulcr. 2019. Genetic Variability Among Xyleborus glabratus Populations Native to Southeast Asia (Coleoptera: Curculionidae: Scolytinae: Xyleborini) and the Description of Two Related Species. Journal of Economic Entomology XX(XX), 2091, 1 – 11.

Dreaden, T.J., M.A. Hughes, R.C. Ploetz, A. Black and J.A. Smith. 2019. Genetic Analyses of the Laurel wilt Pathogen, Raffaelea lauricola, in Asia Provide Clues on the Source of the Clone that is Responsible for the Current USA Epidemic. Forests 2019, 10, 37

Eskalen, A., Stouthamer, R. Lynch, S.C., Twizeyimana, M., Gonzalez, A., and Thibault, T. 2013. Host range of Fusarium dieback and its ambrosia beetle (Coleoptera Scolytinae) vector in southern California. Plant Disease 97938-951.

Gomez, D.F., J. Skelton, M.S. Steininger, R. Stouthamer, P. Rugman-Jones, W. Sittichaya, R.J. Rabaglia, and J. Hulcr1/ 2018. Species Delineation Within the Euwallacea fornicatus (Coleoptera: Curculionidae) Complex Revealed by Morphometric and Phylogenetic Analyses. Insect Systematics and Diversity, (2018) 2(6): 2; 1–11

Jung, T., B. Scanu, C.M. Brasier, J. Webber, I. Milenkovic, T. Corcobado, M. Tomšovský, M. Pánek, J. Bakonyi, C. Maia, A. Baccová, M. Raco, H. Rees, A. Pérez-Sierra & M. Horta Jung. 2020. A Survey in Natural Forest Ecosystems of Vietnam Reveals High Diversity of both New and Described Phytophthora Taxa including P. ramorum. Forests, 2020, 11, 93   https://gcc02.safelinks.protection.outlook.com/?url=https%3A%2F%2Fwww.mdpi.com%2F1999-4907%2F11%2F1%2F93%2Fpdf&data=02%7C01%7C%7Cfcd843919a3348a4a56108d7974039ab%7Ced5b36e701ee4ebc867ee03cfa0d4697%7C0%7C1%7C637144174418121741&sdata=WayrZsxp3P9Kj0h1aDPZnzu4yjDGA2ZEuH9NZITFQF4%3D&reserved=

Vettraino,  A.M., C.M. Brasier, J.F. Webber, E.M. Hansen, S. Green, C.Robin, A. Tomassini, N. Bruni, A. Vannini. 2017. Contrasting microsatellite diversity in the evolutionary lineages of Phytophthora lateralis. Fungal Biology Vol. 121, Issue 2, February 2017, pp. 112-126

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.

Add your comments – should APHIS open trade in maples from Korea?

exit hole of Anapolophora chinensis in Chinese penjing from circa 2001

APHIS has released a risk assessment in response to a petition from the Republic of Korea (ROK) seeking permission to export to the United States bunjae of three maple species (Acer buergerianum Miq., A. palmatum Thunb., and A. pseudosieboldianum Nakai).  The risk assessment is available here.  Scroll down to the deadline February 3.

Comments are accepted until 3 February. To comment, send an email to PPQPRAcomments@aphis.usda.gov. Include the name of the commodity assessed by the draft document (e.g., Korean maple bunjae) in the Subject line.

“Bunjae” is the Korean term for plants for planting equivalent to Japanese “bonsai” or Chinese “penjing”.  In this practice, trees are grown – often for years – using cultivation techniques such as pruning, root reduction, potting, defoliation, and grafting, to produce miniature specimens.

Importation of bunjae plants for planting in the Acer genus from several Asian countries was prohibited temporarily under the agency’s authority under the Plant Protection Act and regulations in 7 CFR 319.37, Subpart H- P4P to limit imports of a new suite of plant taxa as “not authorized pending pest risk analysis” (NAPPRA). 

The NAPPRA listing, finalized in 2013, followed numerous detections of Anoplophora and possibly other pests in penjing shipped from China to the United States, and one outbreak (in Takohma, Washington) that required expensive and destructive eradication measures. At that time, APHIS made the case that no effective mitigation existed to provide protection adequate to the risk. If APHIS is to agree to the ROK petition, it must demonstrate that any mitigation measures it accepts have overcome deficiencies identified in the original proposal to include Acer in the NAPPRA category.

APHIS will address risk management aspects, including and risk mitigation measures, after it has assessed stakeholder and country comments on each pest list or risk assessment. There will be an opportunity to comment on any proposed mitigation measures later.

The risk assessment now open for comment clearly demonstrates that the risks are severe. It concludes that 17 or 18 taxa or groups of species pose a “high” overall risk of introduction, establishment, and impacts.  Another 10 pose an overall “moderate” risk. In each case, the risk assessors concluded that the harvest and shipment procedures outlined in Section 1.4 of the Korean petition would not mitigate the risk. 

While the risk is greatest for maples (Acer spp.), many other types of plants also host pests evaluated in the risk assessment. Thus, the risk often affects fruit trees and grapes as well as alders, birches, dogwoods, elms, magnolias, oaks, poplars, walnuts, willows, rhododendron, even redwood.

My questions and concerns

I note that Table 3 of the risk assessment omits the Asian longhorned beetle (Anoplophora glabripennis), even ‘tho the species is discussed in the text and received an overall risk ranking of “high”. Is this a mistake? If the omission is deliberate, why is the reasoning not discussed in the risk assessment?

The assessments included in this document are brief and leave out many easily obtainable facts regarding damage, especially with regard to the Anoplophora, Lymantria, and Lycorma genera. The risk assessment notes when pest species are polyphagous, but it is uncertain how it incorporates that heightened risk of potential damage.

eradication clearcuts in Takoma, Washington in 2001
reason: escape of A. chinensis from Chinese penjing plants
while they were in “post entry quarantine”

I am also concerned about the document’s treatment of uncertainty.  First, “moderate uncertainty” is defined as “Additional or better evidence may or may not change rating.” How do the assessors evaluate this 50/50 tossup?  My concern is heightened by a statement in the text regarding two taxa, Cacopsylla albopontis & C. pseudosieboldiani. The assessment notes an absence of literature documenting that these taxa are pests in their native range, so their ability to cause damage if introduced to the U.S. is unknown. Consequently, the assessors did not analyze them further “as they are unlikely to cause unacceptable impacts.” As we all know, numerous arthropods and pathogens highly damaging in naïve environments – including in the US — were not pests / were barely known in their native ranges.

Regarding individual species, I note that the assessment says the wood-root fungus Daedalea dickinsii is usually found in older heartwood of roots, trunks, or branches. The assessors conclude that it is unlikely that this fungus would be associated with maple seedlings.  However, bunjae trees are not seedlings; they are deliberately miniaturized woody plants that are often years old.

Re: Anomala cuprea, the assessor seems to downplay the risk because the insect lacks a specific attraction to maples. While I agree that a generalist might be somewhat less likely to be on the bunjae when they are exported, a generalist might pose a threat to a wide range of woody plants if introduced. This higher level of possible impacts needs to be recognized in the assessment.

Several insect groups were excluded from further valuation despite being described as established in Korea and “only associated with Acer species”. Included in this group are several beetles, true bugs (including aphids and leafhoppers), and butterflies/moths (pp. 13-14 of the PRA). I found this language to be completely unclear. If the pests are in Korea and associated with maples, why were they not evaluated?  

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.