Northern red oak – one of the species planted in Europe & China as part of sentinel garden project; photo by F.T. Campbell
During the USDA Interagency Forum on Invasive Species, Dr. Eliana Torres Bedoya, from the Bonello lab at Ohio State, provided insights gained from a sentinel garden project operating for the last five years.
The gardens were established in six locations: two in China in the Nanjing area, one each in Italy, Sweden, Ohio, and New Hampshire. The network required collaboration among scientists in several countries, a difficult task in itself. (Jiri Hulcr of the University of Florida has also stressed the importance of mutually beneficial collaborations.)
The focus was on detecting and identifying novel fungal pathogens abroad before they ever enter a country, in an approach called ex patria sentinel plantings. Altogether, 32 tree species were planted in at least one location. For example, Chinese and European tree species were planted in the U.S. to identify potential threats to China and Europe. Conversely, North American species were planted in Europe and China to detect potential threats to the U.S. As noted, the reciprocity is crucial to establishing and maintaining a long-term relationship.
Key information gained to date:
While the scientists isolated several potential pathogens from symptomatic plants, analysis of all plants’ leaf microbiomes showed that asymptomatic plants harbored many more potential pathogens that had not been isolated.
Healthy plants tend to harbor larger and often more diverse microbial communities. This study found that asymptomatic plants supported a significantly more abundant, richer, and taxonomically diverse leaf-associated fungal community than symptomatic plants. Importantly, this pattern pertains also to the subset of taxa classified as potential plant pathogens.
Detection of the full range of fungal pathogens requires that samples must be collected both early and mid-to-late in the growing season because microbes present differ.
Core leaf microbiomes were associated with specific tree species, no matter where they were planted. However, the constituents of the core microbiome were outnumbered by other organisms driven primarily by the location of the planting. This had been expected.
Other contributing factors – in declining order – were geographic location, tree species, season, and host health status. In other words, the phylogenetic relationship.
The drivers of fungal community composition interact in complex ways. For instance, the effect of the plant’s health on pathogenic fungal communities might depend on the host species. This relationship can be further modulated by seasonal variation and geographic context.
European & Asian trees planted in Ohio as part of the sentinel garden program; photo by P (E) Bonello
Implications:
Sentinel gardens can facilitate identification of novel host-pathogen interactions in symptomatic and asymptomatic plants, so they should be adopted / supported by governmental and regional phytosanitary agencies.
The findings demonstrate the need to expand surveillance beyond symptomatic plants – at both sentinel gardens and plant health border inspection stations. Phytosanitary agencies should employ both full microbial community molecular characterization to detect threats in asymptomatic plants and traditional symptom-based approaches. These modern approaches are described in Munck and Bonello 2018 (full reference at end of the blog).
Enrico Bonello (pers. comm.) thinks it is likely that similar context-dependent interactions among host and fungus species, season, and geography also drive disease infection and virulence.
Eliana Torres Bedoya (pers. comm.) clarifies that the leaf microbiome is the community of microorganisms living on and within tree leaves. These microbes can contribute to protecting trees against pathogens, enhance tolerance to environmental stressors such as drought or pollution, and influence how trees interact with their surroundings. Because the composition of the leaf microbiome responds to changes in climate, location, and tree species, it also serves as a valuable indicator of forest health and environmental change.
There are several approaches to studying microbial communities in leaves. One is the traditional, culture-based method, which relies on isolating and cultivating microorganisms on nutrient media. While this approach is effective for recovering fast-growing and easily culturable taxa, it has a major limitation: the vast majority of environmental microbes are not readily culturable under standard laboratory conditions. As a result, full understanding requires use of culture-independent methods. One technique widely used is metabarcoding. This technique involves extracting total DNA from leaf tissue and amplifying a phylogenetically informative genetic marker specific to the microbial group of interest (for example, the internal transcribed spacer (ITS) region for fungi or the 16S rRNA gene for bacteria). The amplified regions are then sequenced using high-throughput sequencing platforms. After a series of processing steps, the sequences are clustered into Amplicon Sequence Variants (ASVs), which represent unique DNA sequences that can be used as proxies for microbial taxa present in the sample. Torres Bedoya and Bonello used the ASVs for comparative analysis.
Tilia cordata (linden) via Picaryl (seed wings make a great tea!)
In her presentation, Torres Bedoya provided examples of the complexities arising when trying to detect fungi associated with trees. Eleven potentially pathogenic fungal genera were found to be more abundant in asymptomatic Northern red oak (Quercus rubra) trees (a North American species) planted in both Europe and China. Five ASVs were more abundant in asymptomatic Fraxinus mandshurica trees (an Asian species) planted in Sweden. In this case, the season when the leaves were sampled explained a higher proportion of the variance in the community composition than did the health status of the host. Molecular methods detected 10 genera not revealed through isolation from little-leaf linden species (Tilia cordata) trees (a European species) planted in China and the US.
This “proof of concept” study considered only fungi associated with leaves. As shown above, learning the true plant health risk associated with any tree taxon’s leaves is already complicated and resource-demanding. To fully exploit the power of the ex patria sentinel plantings approach, phytosanitary officials must provide additional resources (land, people, equipment, money) to enable screening of all plant parts, above and below-ground, and all potentially pathogenic taxa, including nematodes, phytoplasmas, and viruses. These systems must be maintained over years.
Reference
Munck, I.A., Bonello, P. 2018. Modern approaches for early detection of forest pathogens are sorely needed in the United States. Forest Pathology 48 (5). doi:10.1111/efp.1445
Posted by Faith Campbell
We welcome comments that supplement or correct factual information, suggest new approaches, or promote thoughtful consideration. We post comments that disagree with us — but not those we judge to be not civil or inflammatory.
For a detailed discussion of the policies and practices that have allowed these pests to enter and spread – and that do not promote effective restoration strategies – review the Fading Forests report at https://treeimprovement.tennessee.edu/
ash tree killed by emerald ash borer; photo courtesy of (then) Mayor of Ann Arbor John Hieftje
Since the 1990s, scientists have been trying to the determine costs imposed by invasive species. They hope that measuring monetary costs will motivate political decision-makers to take more assertive actions to counter this ecological treat. As Daigne et al. (2021) point out, too few countries are implementing effective control and mitigation strategies. They say this inaction stems, largely, from undervaluing bioinvasions’ impacts by the general public, stakeholders and decision-makers.
A major step in this effort was creation of the InvaCost database. The goal was to provide a reliable, comprehensive, standardized and easily updatable synthesis of bioinvasions’ monetary costs worldwide.
Several publications based on this database appeared. I have blogged about studies published in 2021 or 2022: a) the costs of bioinvasions generally (Cuthbert et al. 2022); b) the costs imposed by invasive species in protected areas (Moodleyet al. 2022; c) a focus on the “worst” 100 invasives (as determined by the IUCN) (Ahmedet al. 2022); and d) assessing costs associated with various pathways of introduction (Turbelin et al. 2022).
The InvaCost database, as applied in these studies, demonstrated that bioinvasions impose tremendous costs –a minimum of US $1.288 trillion for the period 1970 – 2017. These costs increased on average three times per decade (Daigne et al. 2022).
Still, everyone has recognized that InvaCost data have significant limitations. First, three-quarters of the records in the original database came from North America, Oceania and Europe; and referred to animal taxa, even though plants are a major group of invaders. Also, a large proportion of total invasion costs – for all taxa – probably is undetected. Finally, the many non-market values of species and ecosystems are extremely difficult to calculate (Daigne et al. 2022).
As a result of these deficiencies, the earlier studies discussed in the blogs referenced above substantially underestimated the true costs associated with bioinvasion (Cuthbert et al. 2022).
Now a new study, led by Ismael Soto, finds that the underestimate is huge. Global costs associated with a subset of 162 species (17% of all the species in the InvaCost database) is nearly 17 times higher than reported in the InvaCost database.
Soto et al. (2025) applied species distribution models and macroeconomic data to interpolate these 162 species’ probable impacts in 172 countries
Japanese knotweed – one of the invasive plants proving very costly in Europe, according to I. Soto
The newly identified costs were greatest in Europe; second place fell to North America. This is because both higher damage costs and management expenditures are linked to higher gross domestic product and extent of agricultural area, in addition to environmental suitability. Analysis of monetary costs per unit area revealed that ‘cost hot spots’ are predominantly located in densely populated urban areas and locations hosting key industries. These tend to be in coastal zones, i.e., Europe, the east coast of China, and the east and west coasts of the US.
cypress aphid Cinara cupressi – a threat to both native & plantation trees in Africa; photo by Blackman & Eastop via Wikimedia
The authors found that the greatest increase in estimated costs for countries in Africa and Asia. These countries had not previously recorded any economic costs arising from invasions by these 162 species. I have blogged about forest pest threats in Africa.
The authors also significantly increased estimated costs linked to invasive plants. Daigne et al. found that invasive insects caused ~90% of reported costs in the InvaCost database as of 2022. Vertebrates ranked second, plants third. In contrast, Soto et al. determined that invasive plants had the highest average estimated damage costs (US $42.10 billion) and management expenditures ($0.81 billion).
Substantial total costs were also reported for arthropods, mammals and birds. Reported damage and management costs were much lower for molluscs, fish, reptiles and amphibians. Daigne et al. suggest this might be due to their lower (observable) damage to human infrastructure, research biases leading to fewer studies, or disparities resulting from the filtering process used in their own study.
Williams et al. (2023) focus on insects, which cause damage primarily to agriculture, human health, and forestry. Insects constitute the highest number of species introduced as ‘Contaminants’ (n = 74) and ‘Stowaways’ (n = 43). They also impose the highest costs among species using these two pathways.
Forest insects and pathogens account for less than 1% of the records in the InvaCost database. I believe that this figure reflects significant under-reporting of these invasion events. Even at this paltry level of reported invasions, forest insects and pathogens were responsible for causing 25% of total annual costs ($43.4 billion) (Williams et al. 2023). This discrepancy illustrates the huge economic cost associated with widespread mortality of trees. Yet authorities in most countries continue to provide completely inadequate resources to counter this threat.
The authors of these publications examining economic losses associated with bioinvasion all note that ecological damage is additional. Soto et al. note that bioinvasions contribute to 60% of already recorded global extinctions. Interestingly, the species ranked third using the criterion of monetary damage is the cactus moth Cactoblastis cactorum. This insect threatens flat-padded Opuntia cacti across the United States and in the center of endemism, Mexico.
a flat-padded Opuntia — vulnerable to the cactus moth; photo by F.T. Campbell
Soto et al. found a lag of ~46 years between first (reported) detection of an introduced species and the peak of damage costs. They suggest that the rising monetary cost reflects the species becoming more abundant or occupying a larger area. The authors also say this finding demonstrates the value of implementing mitigation measures as soon as possible. Their finding thus validates others’ advocacy for investing in prevention and rapid response measures (see Cuthbert et al. and Daigne et al.). Soto et al. were cheered by the fact that spending on management measures – when it was reported – often followed soon after a species’ detection – or even before (e.g., prevention).
But Decision-Makers Usually Delay – Why?
Prevention is a hard sell. Decision-makers find it difficult to justify management expenditures before impacts become obvious. By that time, of course, management of the invasion is extremely difficult and expensive – if it is possible at all. Ahmed et al. found particularly effective wording to describe this problem: bioinvasion costs can be deceitfully slow to accrue, so policy makers don’t appreciate the urgency of taking action. Another contributing factor is that when efficient proactive management succeeds in preventing any impact, it paradoxically undermines evidence of the value of this action!
Programs to minimize the economic and ecological consequences of bioinvasion are severely obstructed – if not doomed! – by the following difficulties:
Resources are in short supply. Experts find that demands to address other threats to agriculture or natural systems outcompete appeals to ramp up invasive species efforts.
Prediction is uncertain. Cuthbert et al. found that none of the species with the highest pre-invasion investment was among the top 10 costliest invaders in terms of damages. Cuthbert et al. do not discuss whether this is evidence that the prevention efforts were effective? Or, alternatively, that prevention efforts target the wrong species.
Harm is in the eye of the beholder. Stakeholders’ perceptions of whether an introduced species causes a detrimental impact vary. For example, Moodley et al. point out that species imposing the highest economic costs might not be the ones causing the greatest ecological harm.
Externalities. Those harmed by a bioinvasion often are different from those that decide whether to act. Ahmed et al. argue that this creates a moral dilemma.
These decisions are political — influenced by citizens’ expressed wishes. Changing decision-makers’ perceptions of what is important is up to us!!! Start a parade!!!
SOURCES
Ahmed, D.A., E.J. Hudgins, R.N. Cuthbert, .M. Kourantidou, C. Diagne, P.J. Haubrock, B. Leung, C. Liu, B. Leroy, S. Petrovskii, A. Beidas, F. Courchamp. 2022. Managing biological invasions: the cost of inaction. Biol Invasions (2022) 24:1927–1946 https://doi.org/10.1007/s10530-022-02755-0
Diagne, C., B Leroy, A-C. Vaissière, R.E. Gozlan, D. Roiz, I. Jaric, J-M. Salles, C.A. Bradshaw, and F. Courchamp. 2021. High and rising econ costs of bioinvasions worldwide Published online: 31 March 2021
Moodley, D., E. Angulo, R.N. Cuthbert, B. Leung, A. Turbelin, A. Novoa, M. Kourantidou, G. Heringer, P.J. Haubrock, D. Renault, M. Robuchon, J. Fantle-Lepczyk, F. Courchamp, C. Diagne. 2022. Surprisingly high economic costs of bioinvasions in protected areas. Biol Invasions. https://doi.org/10.1007/s10530-022-02732-7
Soto, I., P. Courtois, A. Pili, E. Tordoni, E. Manfrini, E. Angulo, C. Bellard, E. Briski, M. Buric, R.N. Cuthbert, A. Kouba, M. Kourantidou, R.L. Macêdo, B. Leroy, P.J. Haubrock, F. Courchamp and B. Leung. 2025. Using species ranges and macroeconomic data to fill gap in costs of biological invasions. Nat Ecol Evol doi: 10.1038/s41559-025-02697-5
Turbelin, A.J., C. Diagne, E.J. Hudgins, D. Moodley, M. Kourantidou, A. Novoa, P.J. Haubrock, C. Bernery, R.E. Gozlan, R.A. Francis, F. Courchamp. 2022. Introduction pathways of economically costly invasive alien spp. Biol Invasions (2022) 24:2061–2079 https://doi.org/10.1007/s10530-022-02796-5
Williams, G.M., M.D. Ginzel, Z. Ma, D.C. Adams, F.T. Campbell, G.M. Lovett, M. Belén Pildain, K.F. Raffa, K.J.K. Gandhi, A. Santini, R.A. Sniezko, M.J. Wingfield, and P. Bonello. 2023. The Global Forest Health Crisis: A Public Good Social Dilemma in Need of International Collective Action. Annual Review of Phytopathology Vol. 61, 2023
Posted by Faith Campbell
We welcome comments that supplement or correct factual information, suggest new approaches, or promote thoughtful consideration. We post comments that disagree with us — but not those we judge to be not civil or inflammatory.
For a detailed discussion of the policies and practices that have allowed these pests to enter and spread – and that do not promote effective restoration strategies – review the Fading Forests report at https://treeimprovement.tennessee.edu/
In early May I posted a blog about the Trump Administration’s proposed budget – saying that it would eliminate funding for nearly all USFS research & Forest Health Protection.
I can now provide some additional information.
The Administration has released a supplemental document providing a few details about the severe cuts it is proposing for USFS programs vital to countering bioinvasion in the coming fiscal year (FY2026), which starts October 1st. You can download this document at https://www.whitehouse.gov/wp-content/uploads/2025/05/appendix_fy2026.pdf
Congress has the final say on appropriations – so please!!! inform your representative & senators about why these cuts are disastrous.
USFS [See pages 162-168 of the Appendix]
Research & Development
The Administration requests $0 for R&D. It says it will strategically use existing carryover balances to responsibly terminate research programs & close research stations. Thus, funding for R&D will decrease from the $301 million in FY24 to $44 million in FY26. The Forest Inventory & Analysis will be shifted to the National Forest System and funded at $21.5 million – less than program supporters are seeking.
The proposal does contain an “additional amount” of $26 million for dealing with the consequences of wildfires, hurricanes & other natural disasters that occurred in calendar years 2022, 2023, and 2024. I am confused about this funding.
State, Private, and Tribal Forests
The Administration requests $0 for S,P&T. Again, the proposal says the agency will use existing carryover balances to effectively & responsibly terminate these programs. The number of employees would be cut from 520 employees in FY24 to 37.
Again, the proposal contains an “additional amount” of $208 million for Forest Health Management to deal with the consequences of wildfires, hurricanes & other natural disasters that occurred in calendar years 2022, 2023, and 2024. $14 million of this sum is earmarked for assistance to states in the Northeast that are anticipating an outbreak of eastern spruce budworm (which has been spreading from Canada). In a highly unusual move, the proposal says this funding is not subject to a requirement that grant recipients provide matching funds from non-federal sources. [Is it a coincidence that Maine Senator Susan Collins chairs the Senate Appropriations Committee?]
National Forest System
Total funding for NFS would be $1.5 billion. This includes an “additional amount” of nearly $2.5 billion for expenses related to the consequences of wildfires, hurricanes & other natural disasters that occurred in calendar years 2022, 2023, and 2024. $75 million of this amount is earmarked for construction or maintenance of shaded fuel breaks in the Pacific Northwest.
As I noted above, the Forest Inventory and Analysis program would be placed under the NFS.
I am particularly concerned that the budget proposal provides explicitly for $20 million to improve or maintain landscape & watershed conditions by preventing invasive plant infestations and installing aquatic organism passages, etc. There is no mention of programs intended to address damage caused by non-native insects and pathogens. It appears that the Administration proposes to drop all programs re: these organisms.
The overall objective of NFS programs is defined as managing the forests for productive use & resilience to catastrophic wildfire & provide broad range of ecosystem services. The budget allegedly prioritizes funding of programs designed to increase health & resilience of National Forests & Grasslands – including meeting multiple use requirements for resources on these lands.
The prose no longer says that timber production is the sole purpose of Nation forests – as the original budget stated.
APHIS appears to have survived – although the supplement provides minimal information (on pp. 85 – 87 of the Appendix).
The supplement contains a lengthy description of APHIS’ purpose — to protect America’s agricultural and natural resources from introduced pests. It requests $1.1 billion for FY2026. The only plant pest listed as a priority is exotic fruit flies. Personnel would be cut from 6,142 in FY24 to 5,092. I could find no specifics regarding funding for programs of interest – tree & wood pests, specialty crops, pest detection, and methods development.
Implications for Non-native Insects and Pathogens
Remember that USFS’s research and development program is intended to improve forest managers’ understanding of ecosystems, including human interactions and influences, thereby enabling improvements to the health and use of our Nation’s forests and grasslands. Most importantly to me, this program provides foundational knowledge needed to develop effective programs to prevent, suppress, mitigate, and eradicate the approximately 500 non-native insects and pathogens that are killing America’s trees.
The Forest Health Program provides technical and financial assistance to the states and other forest-management partners to carry out projects (designed based on the above research) intended to prevent, suppress, mitigate, and eradicate those non-native insects and pathogens. The program’s work on non-federal lands is crucial because introduced pests usually start their incursions near cities that receive imports (often transported in crates, pallets, or imported plants).
[FIA might inform all about where such pests are found — but it doesn’t address how to contain their spread, suppress their impacts, or restore the affected tree species.]
Eliminating either or both programs will allow these pests to cause even more damage to forest resources – including timber.
Both supporting research and on-the-ground management must address pest threats across all U.S. forests, including the more than 69% that are located on lands managed by others than the USFS. Already, the 15 most damaging of these pests threaten destruction of 41% of forest biomass in the “lower 48” states. This is a rate similar in magnitude to that attributed to fire (Fei et al. 2019). [This estimate does not include loss of beech beech leaf disease.] It is ironic that the Administration considers the fire threat to be so severe that it has proposed restructuring the government’s fire management structure.
I remind you that the existing USFS R&D budget allocates less than 1% of the total appropriation to studying a few of the dozens of highly damaging non-native pests. I have argued that this program should be expanded, not eliminated. Adequate funding might allow the USFS to design successful pest-management programs for additional pests (as suggested by Coleman et al.).
As a new international report (FAO 2025) notes, genetic resources underpin forests’ resilience, adaptability, and productivity. Funding shortfalls already undercut efforts to breed trees able to thrive despite introduced pests and climate change (the latter threat is still real, although the Administration disregards it). I have frequently urged the Congress to increase funding for USFS programs – which are sponsored primarily by the National Forest System and State, Private, and Tribal, although some are under the R&D program.
I repeat: Please ask your Member of Congress and Senators to oppose these proposed cuts. Ask them to support continued funding for both USFS R&D and its State, Private, and Tribal Programs targetting non-native insects and pathogens. America’s forests provide resources to all Americans – well beyond only timber production and they deserve protection.
Contacting your Representative and Senators is particularly important if they serve on the Appropriations committees.
House Appropriations Committee members:
Republicans: AL: Robert Aderholt, Dale Strong; AR: Steve Womack; AZ: Juan Ciscomani; CA: Ken Calvert, David Valadao, Norma Torres; FL: Mario Diaz-Balart, John Rutherford, Scott Franklin; GA: Andrew Clyde; ID: Michael Simpson; IA: Ashley Hinson; KY: Harold Rogers; LA: Julia Letlow; MD: Andy Harris; MI: John Moolenaar; MO: Mark Alford; MS: Michael Guest; MT: Ryan Zinke; NC: Chuck Edwards; NV: Mark Amodei; NY: Nick LaLota; OH: David Joyce; OK: Tom Cole, Stephanie Bice; PA: Guy Reschenthaler TX: John Carter, Chuck Fleishmann, Tony Gonzales, Michael Cloud, Jake Ellzey; UT: Celeste Maloy; VA: Ben Cline; WA: Dan Newhouse; WV: Riley Moore
Democrats: CA: Pete Aguilar, Josh Harder, Mike Levin; CT: Rosa DeLauro; FL: Debbie Wasserman Schultz, Lois Frankel; GA: Sanford Bishop; HI: Ed Case IL: Mike Quigley, Lauren Underwood; IN: Frank Mrvan; MD: Steny Hoyer, Glenn Ivey; ME: Chellie Pingree; MN: Betty McCollum; NJ: Bonnie Watson Coleman NY: Grace Meng, Adriano Espaillat, Joseph Morelle; NV: Susie Lee; OH: Marcy Kaptur; PA: Madeleine Dean; SC: James Clyburn; TX: Henry Cuellar, Veronica Escobar; WA: Marie Gluesenkamp Perez; WI: Mark Pocan
Senate Appropriations Committee members:
Republicans: AK: Lisa Murkowski; AL: Katie Britt; AR: John Boozman (AR); KS: Jerry Moran; KY: Mitch McConnell; LA: John Kennedy; ME: Susan Collins; MS: Cindy Hyde-Smith; ND: John Hoeven; NE: Deb Fischer; OK: Markwayne Mullin; SC: Lindsey Graham; SD: Mike Rounds TN: Bill Hagerty; WV: Shelley Moore Capito;
Democrats: CT: Chris Murphy; DE: Chris Coons; GA: Jon Ossof; HI: Brian Schatz; IL: Richard Durbin; MD: Chris van Hollen; MI: Gary Peters; NH: Jeanne Shaheen; NM: Martin Heinrich; NY: Kirsten Gillibrand; OR: Jeff Merkley; RI: Jack Reed; WA: Patty Murray; WI: Tammy Baldwin
Addendum
Maintaining the USFS State, Private, and Tribal (SPT) programs is essential to
complying with laws adopted by the Congress (see second page).
meeting the USFS mission of sustaining“the health, diversity, and productivity of the nation’s forests and grasslands to meet the needs of present and future generations.”
ensuring future economic and ecological benefits to Americans.
More than two-thirds of U.S. forests are privately owned or managed by state, local, or tribal governments. These forests provide many benefits, including 89% of America’s timber harvest.[i] SPT is the only federal program providing technical, financial, & educational assistance to these non-federal landowners.
Among the many threats to American forests, the Center for Invasive Species Prevention (CISP) focuses on the threat from insects and pathogens introduced from abroad. More than 41% of forest biomass in the “lower 48” states is at risk to non-native pests already established in the country.[ii] From 2011 to 2020, sap feeders, e.g., hemlock woolly adelgid, killed trees on 635,000 acres; foliage feeders, e.g., spongy moth, killed trees on 948,884 acres.[iii] Additional pests will be introduced and kill more trees.
Non-native pests are introduced primarily in crates, pallets or other packaging made of wood; and in imported plants. These imports – and the pests – usually land in cities or suburbs and establish there. Initially they cause widespread death of urban trees and impose high costs on local governments and property owners who must remove dying trees. The pests also spread. Hemlock woolly adelgid, emerald ash borer, polyphagous and Kuroshio shot hole borers, goldspotted oak borer, sudden oak death, and beech leaf disease have all spread to National forests from cities or suburbs.
The most effective way to protect America’s forests is to find and kill the pests where they first appear – usually in city trees. Waiting to act until a pest reaches National Forest boundaries means failure. Instead, we should expand the Forest Health Management (FHM) Cooperative Lands program to quickly detect, contain, and – if possible – eradicate the pests. With higher appropriations, the STP FHM program could tackle more of the 53 tree species under threat. At present, only four of these species benefit from 95% of FHM projects – eastern oaks, loblolly and ponderosa pines, and hemlocks.[iv]
USFS Research and Development (R&D) program
FHM adopts strategies based on knowledge of pests’ life histories and traits gained through research conducted or sponsored by the USFS R&D program. CISP urges you to support continued funding for the USFS Research and Development (R&D) program. However, we advocate a realignment: raise the proportion of research funding allocated to invasive species from the current paltry level of 1% to 5%. Funding for studying non-native pests has decreased 70% since FY2010 despite new pests attacking our forests. As a result, the Forest Service is hampered from developing effective programs to prevent, suppress, and eradicate most non-native pests.
Another crucial strategy for reducing loss of tree species to non-native pests is breeding trees able to thrive despite introduced pests. Currently these projects are supported – inadequately – by all three USFS divisions: R&D, SPT, and National Forest System (NFS).
The model program is the Dorena Genetic Resource Center. The Center has bred Western white pine and Port-Orford-cedar trees resistant to introduced pathogens; these trees are now being planted. Promising projects target the pathogens killing whitebark pine, American chestnut, American elm, and Hawaiian koa. Projects at earlier stages address ash, beech, and ʻōhiʻa.
Lesson: federal dollars, wisely invested, can mitigate the damage caused by invasive species. CISP asks you to support continuing these programs so that America can restore threatened trees to our forests.
Complying with the Law
The Cooperative Forestry Assistance Act of 1974
Section 2 (a) Findings …—
(1) most of the productive forest land of the United States is in private, State, and local governmental ownership, and the capacity of the United States to produce renewable forest resources is significantly dependent on such non-Federal forest lands;
(b) Purpose.—… authorize[s] the Secretary …, with respect to non-Federal forest lands … to assist in—
…
(3) the prevention and control of insects and diseases affecting trees and forests;
(c) Priorities.—In allocating funds … , the Secretary shall focus on the following national private forest conservation priorities, …:
…
(2) Protecting forests from threats, including … invasive species, insect or disease outbreak, … and restoring appropriate forest types in response to such threats.
(e) Policy. … it is in the national interest for the Secretary to work through and in cooperation with State foresters, or equivalent State officials, nongovernmental organizations, and the private sector …
Healthy Forests Restoration Act of 2003
Sec. 401(a) FINDINGS.—(1) high levels of tree mortality resulting from insect infestation (including the interaction between insects and diseases) may result in — (A) increased fire risk; … (E) degraded watershed conditions; (F) increased potential for damage from other agents of disturbance, including exotic, invasive species; and (G) decreased timber values;
…
(3) the hemlock woolly adelgid is— (A) destroying streamside forests throughout the midAtlantic and Appalachian regions; (B) threatening water quality and sensitive aquatic species; and (C) posing a potential threat to valuable commercial timber land in northern New England;
(4)(A) the emerald ash borer … has quickly become a major threat to hardwood forests …; and (B) … threatens to destroy more than 692,000,000 ash trees in forests in Michigan and Ohio alone, and between 5 and 10 percent of urban street trees in the Upper Midwest;
…
(11)(A) often, there are significant interactions between insects and diseases; (B) many diseases (such as white pine blister rust, beech bark disease, and many other diseases) can weaken trees and forest stands and predispose trees and forest stands to insect attack; and (C) certain diseases are spread using insects as vectors (including Dutch elm disease and pine pitch canker); …
(b) … The purposes of this title are— (1) to require the Secretary to develop an accelerated basic and applied assessment program to combat infestations by forest-damaging insects and associated diseases; (2) to enlist the assistance of colleges and universities …, State agencies, and private landowners to carry out the program; and (3) to carry out applied silvicultural assessments.
Sec. 402 Definitions
…
(3) FOREST-DAMAGING INSECT. … means … (D) a gypsy moth; (E) a hemlock woolly adelgid; (F) an emerald ash borer; … and (I) such other insects … identified by the Secretary.
[i] Oswalt, S.N., .W.B. Smith, P.D. Miles, & S.A. Pugh. Forest Resources of the United States, 2017 Uport WO-97SDA Forest Service Gen. Tech. Report WO-97. March 2019
[ii] Fei, S., R.S. Morin, C.M. Oswalt, and A.M. 2019. Biomass losses resulting from insect and disease invasions in United States forests. PNAS August 27, 2019. Vol. 116 No. 35 17371–17376
[iii] Coleman, T.W, A.D. Graves, B.W. Oblinger, R.W. Flowers, J.J. Jacobs, B.D. Moltzan, S.S. Stephens, R.J. Rabaglia. 2023. Evaluating a decade (2011–2020) of integrated forest pest management in the United States. Journal of Integrated Pest Management, (2023) 14(1): 23; 1–17
We welcome comments that supplement or correct factual information, suggest new approaches, or promote thoughtful consideration. We post comments that disagree with us — but not those we judge to be not civil or inflammatory.
For a detailed discussion of the policies and practices that have allowed these pests to enter and spread – and that do not promote effective restoration strategies – review the Fading Forests report at https://treeimprovement.tennessee.edu/
Scientists at the University of Minnesota have begun a project to assess the usefulness of remote sensing to detect the presence of emerald ash borer (EAB) earlier in the invasion. Previous studies had suggested that EAB infestation reduces leaf photosynthesis and transpiration before the yellowing of leaves. Scientists can monitor these changes from space. The project is now testing whether such monitoring can reliably detect EAB infestations at an early stage … The project began in April 2025 and is scheduled to end in December 2028.
Specific research questions to be addressed are:
How effective is remote sensing in detecting EAB years ahead of crown dieback?
Do changes in photosynthesis and transpiration caused by climate stresses (e.g. droughts and floods) differ from those caused by EAB infestation?
How quickly does an EAB infestation progress and spread spatially?
If remote sensing proves to be useful, land managers will have a new tool allowing them to intervene early enough to treat ash trees, before it is too late. The project team will build on existing detection protocols in collaboration with the USDA Forest Service, Minnesota Department of Agriculture (MDA), and Minnesota Department of Natural Resources (DNR).
I note that the Pacific coast states would benefit greatly from being able to identify satellite EAB outbreaks.
ash-dominated swamp in the Ankeny National Wildlife Refuge along the Willamette River in Oregon; photo by Wyatt Williams, Oregon Department of Forestry
I hope that this tool might also be tested for efficacy re: the non-native wood-borers attacking oaks and other trees in the Pacific coast states, e.g.goldspotted oak borer, Mediterranean oak borer, and three species of invasive shot hole borers.
Posted by Faith Campbell
We welcome comments that supplement or correct factual information, suggest new approaches, or promote thoughtful consideration. We post comments that disagree with us — but not those we judge to be not civil or inflammatory.
For a detailed discussion of the policies and practices that have allowed these pests to enter and spread – and that do not promote effective restoration strategies – review the Fading Forests report at https://treeimprovement.tennessee.edu/
Coast live oak killed by GSOB at William Heise State Park, San Diego County; photo by F.T. Campbell
Forest entomologists in southern California have organized the first of what they intend to be annual an annual “GSOB blitz”. The goldspotted oak borer has established widely in the region and has killed tens of thousands of California black and coast live oaks.
The goal of the “blitz” is to train community members & organizations in detecting and reporting presence of this beetle. Survey events are scheduled in six Southern California Counties between June 1-June 15, 2025. Participants are welcome from the general public, private business, public or community organizations, etc.
The Trump Administration’s budget for Fiscal Year 2026 [which begins at the end of September 2025] proposes to eliminate funding for nearly all USFS research & Forest Health Protection.
Proposed Cuts to USFS Research: Timber the Sole Aim
In a letter from Office of Management and Budget (OMB) to Senate Appropriations Committee Chair Susan Collins (R-Maine, Director Russell Vought says the Administration wants to manage National forests “for their intended purpose of producing timber” and that the research and development program “is out of step with the practical needs of forest management for timber production.” The Administration proposes to eliminate funding for USFS research projects other than the small portion covering Forest Inventory and Analysis.
I understand that the USFS Chief told various NGOs that his job is to run the National Forest System, increase timber production by 40%, and do nothing else.
This single aim conflicts with the 1897 legislation founding and authorizing the USFS. It also violates provisions of subsequent legislation such as the Multiple-Use Sustained-Yield Act of 1960 and the National Forest Management Act of 1976. It also departs from long-standing US Forest Service policy – which is the intention.
The “intended purpose” of establishing “forest reserves” [which were later renamed National forests] has never been solely for timber production. The “Organic Act” of 1897 provided that any new forest reserves would have to meet the criteria of forest protection, watershed protection, and timber production.
Specifically, theORGANIC ACT OF 1897 [PUBLIC–No.2.] says:
“[All public lands heretofore designated and reserved by the President of the US under the provisions of the Act [of] March 3rd 1891, the orders for which shall be and remains in full force and effect, unsuspended and unrevoked, and all public lands that may hereafter be set aside as public forest reserves under said act, [these were the “forest reserves,”predecessors of “National Forests]” shall be as far as practicable controlled and administered in accordance with the following provisions:
“No public forest reservation shall be established, except to improve and protect the forest within the reservation, or for the purpose of securing favorable conditions of water flows, and to furnish a continuous supply of timber for the use and necessities of [US] citizens; but it is not the purpose or intent of these provisions, or of the Act providing for such reservations, to authorize the inclusion therein of lands more valuable for the mineral therein, or for agricultural purposes, than for forest purposes.”
The Department of the Interior, which then managed these forest reserves, promptly issued implementing regulations. The regulations stated that the “object” of forest reservations was:
“2. Public forest reservations are established to protect and improve the forests for the purpose of securing a permanent supply of timber for the people and insuring conditions favorable to continuous water flow.”
Therefore, I think the Administration has exaggerated the emphasis on timber production by calling it “the” intended purpose of the original establishment of National forests. The Administration has also chosen to ignore subsequent legislation, such as the Multiple-Use Sustained-Yield Act of 1960 and the National Forest Management Act of 1976.
Sec. 13 of the NFMA limits the sale of timber from each national forest to a quantity equal to or less than a quantity which can be removed from such forest annually in perpetuity on a sustained-yield basis. This limit might be exceeded under certain circumstances, but such excess must still be consistent with the multiple-use management objectives of the land management plan. Further, Sec. 14 requires public input into any decision to raise timber allowances.
During his period as Chief (1905 – 1910), Gifford Pinchot invented and applied the concept of “conservation” of natural resources. As a result “wise use” became accepted as the national goal.
Culminating more than a century of legislation and informed policy, the mission of the USDA Forest Service is to “sustain the health, diversity, and productivity of the nation’s forests and grasslands to meet the needs of present and future generations.”
Proposed Cuts to State, Private, and Tribal Forests
The budget also cuts $303 million from the State, Private, and Tribal Forests program. (I understand this zeroes out the entire program). The OMB Director alleges that the program has been “plagued by oversight issues, including allegation of impropriety by both the Agency and State governments.” I understand that this would eliminate the cooperative projects managed by the Forest Health Protection program, too.
Implications for Non-native Insects and Pathogens
Remember that USFS’s research and development program is intended to improve forest managers’ understanding of ecosystems, including human interactions and influences, thereby enabling improvements to the health and use of our Nation’s forests and grasslands. Most importantly to me, this program provides foundational knowledge needed to develop effective programs to prevent, suppress, mitigate, and eradicate the approximately 500 non-native insects and pathogens that are killing America’s trees.
The Forest Health Program provides technical and financial assistance to the states and other forest-management partners to carry out projects (designed based on the above research) intended to prevent, suppress, mitigate, and eradicate those non-native insects and pathogens. The program’s work on non-federal lands is crucial because introduced pests usually start their incursions near cities that receive imports (often transported in crates, pallets, or imported plants).
Eliminating either or both programs will allow these pests to cause even more damage to forest resources – including timber.
Both supporting research and on-the-ground management must address pest threats across all U.S. forests, including the more than 69% that are located on lands managed by others than the USFS. Already, the 15 most damaging of these pests threaten destruction of 41% of forest biomass in the “lower 48” states. This is a rate similar in magnitude to that attributed to fire (Fei et al. 2019). It is ironic that the Administration considers the fire threat to be so severe that it has proposed restructuring the government’s fire management structure.
I remind you that the existing USFS R&D budget allocates less than 1% of the total appropriation to studying a few of the dozens of highly damaging non-native pests. I have argued that this program should be expanded, not eliminated. Adequate funding might allow the USFS to design successful pest-management programs for additional pests (as suggested by Coleman et al.).
As a new international report (FAO 2025) notes, genetic resources underpin forests’ resilience, adaptability, and productivity. Funding shortfalls already undercut efforts to breed trees able to thrive despite introduced pests and climate change (the latter threat is still real, although the Administration disregards it). I have frequently urged the Congress to increase funding for USFS programs – which are sponsored primarily by the National Forest System and State, Private, and Tribal, although some are under the R&D program.
Please ask your Member of Congress and Senators to oppose these proposed cuts. Ask them to support continued funding for both USFS R&D and its State, Private, and Tribal Programs targetting non-native insects and pathogens. America’s forests provide resources to all Americans – well beyond only timber production and they deserve protection.
Contacting your Representative and Senators is particularly important if they serve on the Appropriations committees.
House Appropriations Committee members:
Republicans: AL: Robert Aderholt, Dale Strong; AR: Steve Womack; AZ: Juan Ciscomani; CA: Ken Calvert, David Valadao, Norma Torres; FL: Mario Diaz-Balart, John Rutherford, Scott Franklin; GA: Andrew Clyde; ID: Michael Simpson; IA: Ashley Hinson; KY: Harold Rogers; LA: Julia Letlow; MD: Andy Harris; MI: John Moolenaar; MO: Mark Alford; MS: Michael Guest; MT: Ryan Zinke; NC: Chuck Edwards; NV: Mark Amodei; NY: Nick LaLota; OH: David Joyce; OK: Tom Cole, Stephanie Bice; PA: Guy Reschenthaler TX: John Carter, Chuck Fleishmann, Tony Gonzales, Michael Cloud, Jake Ellzey; UT: Celeste Maloy; VA: Ben Cline; WA: Dan Newhouse; WV: Riley Moore
Democrats: CA: Pete Aguilar, Josh Harder, Mike Levin; CT: Rosa DeLauro; FL: Debbie Wasserman Schultz, Lois Frankel; GA: Sanford Bishop; HI: Ed Case IL: Mike Quigley, Lauren Underwood; IN: Frank Mrvan; MD: Steny Hoyer, Glenn Ivey; ME: Chellie Pingree; MN: Betty McCollum; NJ: Bonnie Watson Coleman NY: Grace Meng, Adriano Espaillat, Joseph Morelle; NV: Susie Lee; OH: Marcy Kaptur; PA: Madeleine Dean; SC: James Clyburn; TX: Henry Cuellar, Veronica Escobar; WA: Marie Gluesenkamp Perez; WI: Mark Pocan
Senate Appropriations Committee members:
Republicans: AK: Lisa Murkowski; AL: Katie Britt; AR: John Boozman (AR); KS: Jerry Moran; KY: Mitch McConnell; LA: John Kennedy; ME: Susan Collins; MS: Cindy Hyde-Smith; ND: John Hoeven; NE: Deb Fischer; OK: Markwayne Mullin; SC: Lindsey Graham; SD: Mike Rounds TN: Bill Hagerty; WV: Shelley Moore Capito;
Democrats: CT: Chris Murphy; DE: Chris Coons; GA: Jon Ossof; HI: Brian Schatz; IL: Richard Durbin; MD: Chris van Hollen; MI: Gary Peters; NH: Jeanne Shaheen; NM: Martin Heinrich; NY: Kirsten Gillibrand; OR: Jeff Merkley; RI: Jack Reed; WA: Patty Murray; WI: Tammy Baldwin
SOURCES
Coleman, T.W, A.D. Graves, B.W. Oblinger, R.W. Flowers, J.J. Jacobs, B.D. Moltzan, S.S. Stephens, R.J. Rabaglia. 2023. Evaluating a decade (2011–2020) of integrated forest pest management in the United States. Journal of Integrated Pest Management, (2023) 14(1): 23; 1–17
FAO. 2025. The Second Report on the State of the World’s Forest Genetic Resources. FAO Commission on Genetic Resources for Food and Agriculture Assessments, 2025. Rome.
Fei, S., R.S. Morin, C.M. Oswalt, and A.M. 2019. Biomass losses resulting from insect and disease invasions in United States forests. PNAS August 27, 2019. Vol. 116 No. 35 17371–17376
Posted by Faith Campbell
We welcome comments that supplement or correct factual information, suggest new approaches, or promote thoughtful consideration. We post comments that disagree with us — but not those we judge to be not civil or inflammatory.
For a detailed discussion of the policies and practices that have allowed these pests to enter and spread – and that do not promote effective restoration strategies – review the Fading Forests report at https://treeimprovement.tennessee.edu/
Guest blog by Kristy M. McAndrew, Department of Forestry, Mississippi State University
Virginia juniper (Juniperus virginiana) preforming its ecological role: succession in a field (in Ohio); photo by Greg Hume via Wikimedia
Spread of non-native species is a facet of global change that is an unintended consequence of the modern global trade network. Despite efforts put in place to limit such transport, such as International Standards for Phytosanitary Measures (ISPMs), unintentional spread of species continues, and thus, an important part of forest health research and management includes non-native monitoring and control efforts. As other aspects of global change, such as climate and weather patterns, shift, the dynamics between native landscapes and introduced pests may unexpectedly shift as well. For example, increased climate stress of tree hosts may weaken tree defenses, allowing species that historically have not been pests of concern to reach pest status.
Japanese cedar longhorned beetle (Callidiellum rufipenne; JCLB) is a wood boring beetle in the longhorned beetle family, Cerambycidae. The adults are reddish brown in color, and relatively small for longhorned beetles, at only around 1 cm in length. Japanese cedar longhorned beetle has a long history of establishing outside of its native range but has largely been considered a non-issue. It has long been disregarded as a pest because it feeds primarily on dead or dying trees in both the native and invaded ranges. However, there are more examples of these beetles feeding on stressed, but alive, trees in North America. Therefore, I think it is an important insect to take a closer look at.
Life cycle
These beetles have a one-year life cycle, most of which is spent inside a host tree. Adults emerge from host trees in the early spring and seek out other adults to mate with and trees to lay eggs on. Eggs are laid on thin parts of bark or in bark crevices, and when the eggs hatch larvae chew beneath the bark where they feed on the phloem until they have completed larval development. Once larvae are fully developed, they burrow further into the tree, into the xylem tissue, where they pupate, overwinter as fully formed adults, and continue the cycle the following spring.
Native range
The native range of JCLB is eastern Asia. It is common throughout the Korean peninsula and across the islands of Japan. It is also considered native to Eastern China and Russia. Within the native range JCLB is found primarily on dead and/or dying trees and is thus considered a secondary pest. On dead trees they can be found on any diameter of dead woody material, but on declining trees they will likely be in the small diameter branches and stems.
Arborvitae (Thuja occidentalis); photo by James St. John via Flickr
Invasion history
Japanese cedar longhorned beetle was first documented as an invasive pest in the early 1900s in France, and since then has established in at least fifteen countries (Clément 2023). Most of these countries are in Europe, but the United States and Argentina also have established populations. As with most woodboring insects, the invasion pathway is believed to have been wood packaging material being transported via global trade routes. Between 1914 and 2022 it was intercepted over 700 times (reviewed by KM). Since the implementation of ISPM No. 15, only six interceptions have been reported up to 2022 (USDA APHIS data reviewed by K.M.). [For Faith’s view on the regulation of wood packaging, see Fading Forests II and III (links provided at the end of this blog) and earlier blogs posted here under the category “wood packaging”. esp. 1 from 2015].
A USDA risk assessment completed in 2000 suggested other possible pathways of introduction, including balled nursery stock, green logs, and pruned branches (USDA APHIS and Forest Service, 2000).
In terms of establishments in North America, JCLB was first detected in natural forests in North Carolina in 1997. It was soon discovered in Connecticut in 1998; in neighboring New York in 1999; and in Massachusetts, New Jersey, and Rhode Island in 2000. It was quickly discovered feeding on live arborvitae (also called northern white cedar; Thuja occidentalis) in these invaded regions. JCLB has since been found in Pennsylvania (in 2010) and Maryland (in 2011). It is important to note that it is not clear when this species truly established, because of its previously discussed long history of being intercepted in ports of entry.
Most introduced populations of JCLB are found in either dead hosts or in the damaged/dead limbs of live hosts. In Buenos Aires, for example, storm-damaged trees with broken limbs are often where beetles are collected (Turienzo 2007). In the United States, eastern red cedar (Juniperus virginiana) and common juniper (Juniperus communis ) are the two native species most commonly affected, but so far there is no evidence of live trees of these species being infested (Maier 2007). However, a growing concern in the United States is that JCLB has been documented on live trees – particularly in urban environments. These trees are typically arborvitae, and they are typically stressed urban trees that have been overwatered and often show signs and symptoms of other health issues.
Host breadth
The host breadth of JCLB encompasses much of the family Cupressaceae. Maier (2007) identified 19 potential hosts from the literature and research, with the vast majority (14) of the hosts being Cupressaceae species, which is indicative of JCLB being a relative generalist, especially when considering species in the cypress family. This is important, because there are over 130 species within Cupressaceae worldwide that could be suitable hosts for JCLB, meaning host will not be a limiting factor in many invasion scenarios for this insect. Most often trees infested by JCLB need to be either stressed or dead, which limits suitability to an extent. However, many landscape trees are inherently stressed, whether it be from a history of roots being balled and wrapped in burlap, being planted in less than ideal scenarios, or being overwatered.
A few reports from research in Japan record JCLB feeding on plants in Pinaceae, primarily Pinus and Abies species. One article reports use of Larix kaempferi; another documented JCLB on the Taxaceae species, Taxus cuspidata. North American pine (Pinus spp.) and fir (Abies spp.) species have not been tested, but if they are revealed as suitable that would increase the availability of hosts in North America significantly.
In southern New England at least nine species have been confirmed as suitable, all of which are in the family Cupressaceae. Native and abundant junipers, such as Juniperus virginiana, appear to be highly suitable hosts. Additional host testing would be beneficial – especially Cupressaceae species that are either threatened or have a limited range. Within the United States there are a total of 28 native Cupressaceae species. Thus the suitable range (in terms of hosts) covers the entire Eastern half of North America through central Texas, most of the Pacific Coast, and widespread but spotty/disjunct areas throughout the Intermountain West and High Plains regions.
Atlantic white cedar swamp (Chamaecyparis thyoides) in Brendan Byrne State Forest, New Jersey; photo by Famartin via Wikimedia
Suitability
Tools such as environmental niche models can give helpful estimates of suitability. For species that are typically secondary pests, such as JCLB, it can be difficult to obtain non-biased data with good coverage to make reliable predictions. Preliminary research (unpublished) has been completed to estimate suitable habitat with limited occurrence records from the native range. Despite limited occurrences, models performed well and estimated moderate to high suitability in most temperate regions globally. These preliminary models are still being optimized by working with collaborators within the native range of JCLB to increase the number of occurrences. It is also important to note that these models are only accounting for climate data. Host data was not included, but Cupressaceae species are abundant globally, and therefore host availability is not likely a limiting factor for JCLB in establishing in regions.
Importance of monitoring species
While JCLB is still mostly limited to dead, dying trees, many of the species it may affect in the Eastern United States are already of heightened conservation concern. Wetland Cupressaceae, such as bald cypress (Taxodium distichum) and Atlantic White Cedar (Chamaecyparis thyoides), are valuable in terms of ecosystem services they provide in coastal, and inland, wetlands. These wetlands are encountering heightened stress in the form of increasing saltwater intrusion, increased storm strength, and changing landscapes, all of which may predispose trees to insect attack. Japanese cedar longhorned beetle has been successfully reared out of logs of Atlantic White Cedar, but thankfully has not been documented on live trees of this species (Maier 2009)[Ma1] . Bald cypress has not yet been tested for suitability. It is unknown if the stressors these trees are facing and will continue to face will impact JCLB’s ability to infest these landscapes, or if they will remain restricted to dead trees in these coastal forests. Regardless, given JCLB already has an established foothold in the Eastern United States, it is important to better understand the potential impacts of this insect.
First steps to understanding those impacts include 1) better documenting the host range in the regions and 2) determining the climate that may support the species. Hopefully we can continue research in these areas to best manage this non-native pest.
Much of the research conducted on JCLB in North America took place almost 20 years ago (Maier 2007, 2009), so updated sampling has potential to provide a wealth of information regarding spread rate, suitable climate, and establishment patterns.
bald cypress(Taxodium distichum); photo by Kej605 via Wikimedia; it is unknown whether this species is vulnerable to the Japanese cedar longhorned beetle
Sources
Clément F. 2023. Le point sur la distribution en France et en Europe de Callidiellum rufipenne (Motschulsky, 1861)(Coleoptera, Cerambycidae, Cerambycinae, Callidiini). Le Coléoptériste. 26(3):188–203.
Maier CT. 2007. Distribution and Hosts of Callidiellum rufipenne (Coleoptera: Cerambycidae), an Asian Cedar Borer Established in the Eastern United States. JOURNAL OF ECONOMIC ENTOMOLOGY. 100(4).
Maier CT. 2009. Distributional and host records of Cerambycidae (Coleoptera) associated with Cupressaceae in New England, New York, and New Jersey. Proceedings of the Entomological Society of Washington. 111(2):438–453. https://doi.org/10.4289/0013-8797-111.2.438
Turienzo P. 2007. New records and emergence period of Callidiellum rufipenne (Motschulsky, 1860) [Coleoptera:Cerambycidae: Cerambycinae: Callidiini] in Argentina. Boletín de Sanidad Vegetal, Plagas. 33:341–349.
United States Department of Agriculture Animal and Plant Health Inspection Service and Forest Service 2000. (Pasek, J.E., H.H. Burdsall, J.F. Cavey, A. Eglitis, R.A. Haack, D.A. Haugen, M.I. Haverty, C.S. Hodges, D.R. Kucera, J.D. Lattin, W.J. Mattson, D.J. Nowak, J.G. O’Brien, R.L. Orr, R.A. Sequeira, E.B. Smalley, B.M. Tkacz, W.W. Wallner) Pest Risk Assessment for Importation of Solid Wood Packing Materials into the United States. USDA APHIS and Forest Service. August 2000.
Posted by Faith Campbell
We welcome comments that supplement or correct factual information, suggest new approaches, or promote thoughtful consideration. We post comments that disagree with us — but not those we judge to be not civil or inflammatory.
For a detailed discussion of the policies and practices that have allowed these pests to enter and spread – and that do not promote effective restoration strategies – review the Fading Forests report at https://treeimprovement.tennessee.edu/
We have already seen threats to the Clean Air Act of 1970, the Clean Water Act of 1972 from the Trump Administration. Now the Endangered Species Act of 1973 (16 U.S.C. 1531-1544) faces severe risks.
The Washington Post has reported that the Trump Administration is saying that scientists’ ability to revive extinct species through biotechnology justifies relaxing legal protections. The Post quoted Interior Secretary Doug Burgum as saying that innovation – not government regulation — will save species. He has already met with Dallas-based Colossal Biosciences about using its animals in federal conservation efforts, as well as for potential species restoration. I note that having a few “engineered” specimens living in a zoo is not the goal of the Act or sensible biodiversity conservation programs.
This is just the Administration’s latest maneuver aimed at reducing the Act’s protections, which have been in place since adoption of the Endangered Species Act in 1973. The Fish and Wildlife Service — an agency in the Interior Department — has sought White House comments on a proposed redefinition of “harm” under the act. The term is not defined in the text of the Act, so a rule change could allow for significant reductions in protections, especially regarding listed species’ habitats.
Already, President Trump and his administration have overridden endangered species protections. First, he demanded that the Bureau of Reclamation open water transfer systems to drain water from a Northern California river system to southern California. Ostensibly the action was to protect the area from the devastating wildfires, although scientists declared that a lack of water for firefighters was not the reason the fires caused so much damage. The water had been stored, in part, to protect the habitat of the delta smelt.
President Trump also has revived the long-dormant “God Squad.” a federal committee that can override protections for endangered species. Members include Secretary Burgum and five other high-level officials. It was created by Congressional amendment in the late 1970s, during the fight over whether to build the Tellico Dam on the Tennessee River. It is empowered to approve projects even if they result in the extinction of a species.
In February, Interior Secretary Burgum also rescinded guidance adopted by the Biden Administration aimed at minimizing ship strikes on the Rice’s whale, one of the most endangered marine mammals. He has also ordered staff to consider economic factors when deciding habitat protections.
Other threats came earlier. Elon Musk’s SpaceX launch site is only about 10 miles from Aransas National Wildlife Refuge, which provides winter habitat for one of the “iconic” endangered species, whooping cranes. The Midwestern population of piping plovers is also listed as endangered; it winters along the Gulf coast, including at Aransas. The Refuge is home to 400 bird species, primarily ducks, herons, egrets, ibises, and roseate spoonbills. The few studies of noise impacts on birds focus on nesting – which neither whoopers nor plovers engage in while at Aransas … Still ….
Another refuge — in the middle of the Pacific Ocean – is also under threat from rocket activities. The Post reports that the U.S. Space Force – a branch of the U.S. Air Force – will soon publish an Environmental Assessment regarding plans to build two landing pads on Johnston Atoll. The facilities are intended to expedite movement of military cargo around the globe – by transporting it on large commercial rockets. Johnson Atoll is an unincorporated U.S. territory consisting of four tiny islands about 800 miles southwest of Honolulu. Although tens of thousands of red-tailed tropicbirds, red-footed boobies and sooty terns nest on the atoll, the Space Force said in its notice of intent that it expects the construction and operation of the demonstration project will have no significant environmental impact. This finding has been criticized by several organizations, including the Conservation Council for Hawaii, National Wildlife Refuge Association, and Union of Concerned Scientists. See also this statement by the American Bird Conservancy.
red-footed booby adult & nestling on Johnson Atoll; photo by Jordan Akiyama, USFWS via Flickr
One concern is that construction and operation could re-introduce various invasive species. The Post mentions yellow crazy ants; their acids can cause deformities in birds and, in some cases, deadly infections. The U.S. Fish and Wildlife Service spent a decade eradicating the ants. I note that rats very often are introduced to remote islands by cargo ships and are a significant threat to ground-nesting birds.
red-tailed tropic bird swarmed by yellow crazy ants – on Johnson Atoll; photo by Sheldon Plentovich USFWS via Flickr
Congressional Republicans – who now control both houses of the legislature — are preparing amendments to the Endangered Species Act that would slash protections for at-risk species that are – or might later be – qualified for listing under the Act. One approach is to legislatively remove, or “delist,” those species that have gotten in the way of various activities. The Post names gray wolves and grizzly bears, which ranchers say prey on livestock; plus a lizard in Texas oil country; and the northern long-eared bat, which lives in forests that the timber industry wants to log.
range of northern long-eared map in US & Canada
Citing the fact that only 3% of listed species have recovered, Representative Bruce Westerman of Arkansas, Chairman of the House Committee on Natural Resources, wants to amend the Act to give more power to states. He also plans to limit courts’ power to review agencies’ decisions to remove protections for plants and animals.
Posted by Faith Campbell
We welcome comments that supplement or correct factual information, suggest new approaches, or promote thoughtful consideration. We post comments that disagree with us — but not those we judge to be not civil or inflammatory.
For a detailed discussion of the policies and practices that have allowed these pests to enter and spread – and that do not promote effective restoration strategies – review the Fading Forests report at https://treeimprovement.tennessee.edu/
One of the pathways is wooden handicrafts – identified as a pathway more than a decade ago but only partially regulated. The other is new: wood used to decorate aquaria. Two new papers demonstrate that both carry multiple and diverse taxa of fungi. At least 30 have never been detected before in the US. They include both plant and human pathogens.
Both sets of authors call on the U.S. Department of Agriculture to remedy ineffective regulations. However, it appears unlikely that APHIS will be able to do so now, when its budget and staff are being cut. (Lawsuits might restore some of these resources.) Extending APHIS’ authority to regulate organisms that are not plant pests would require Congress to adopt new legislation.
Live Pathogens Imported in Wooden Handicrafts
In 2022, Jason Smith and others (full citation at the end of this blog) published an analysis of the viability and diversity of fungi brought to the U.S. in imported wooden handicrafts. They isolated 47 fungal taxa originating from at least seven countries on three continents. All remained viable despite being subjected to various phytosanitary requirements. Fourteen were plant pathogens; 17 were human pathogens; several were producers of mycotoxins. Three taxa have not been reported before in North America: Bipolaris austrostipae, Paecilomyces formosus, and Xylaria badia. All three are plant pathogens. P. formosus is a human pathogen as well.
Three quarters of the taxa have tolerances that would increase their likelihood of surviving standard heat or fumigation treatments.
Smith et al. point out that wood from sources other than China are subject only to general permit requirements outlined here. Only if pests are detected during port inspections are quarantine actions taken.
APHIS has certified more than a thousand Chinese exporters of handicrafts that incorporate wood, straw, or other biological components. APHIS encourages importers to buy products from these businesses. However, importers may choose other sources. In that case, the product must be treated before entry.
However, as Smith et al. point out, regulation and treatments are focused on arthropods. They do not address the risk from disease pathogens. Smith et al. conclude that these regulations are insufficient to protect plants from damage.
A second issue is that USDA has no authority to regulate organisms that pose a risk to non-plant hosts, including humans. This is especially worrying in this case because many of the handicrafts being intended for food preparation and distribution. Others are handled by purchasers during crafting activities, or used in bath and beauty products.
photo by Sean Welton via Flickr
Live Fungi Imported in Decorative Wood for Aquaria
A second study has expanded the types of material raising concern. The Minnesota Invasive Terrestrial Plant and Pests Center sponsored research that confirms that pieces of wood imported to decorate aquatic and terrestrial aquaria support live fungal-like organisms. The scientists worry that the wood – and the organisms it harbors – might be discarded in a way that facilitates escape and establishment of these organisms. Another possible route of escape is if the water from these mini-habitats is dumped into surface waters.
Blanchette, Rajtar, Lochridge and Held (2025; full citation at end of this blog) obtained 44 samples of such wood from on-line sellers. Some samples had evidence of fungal infestation. Many of the wood pieces were extensively degraded, with large holes, some of which held mud or sand.
The scientists isolated 202 cultures representing 123 fungal taxa in the Ascomycota, Basidiomycota, and Mucoromycota. They detected no Oomycota. The organisms included 30 or 31 species that have not previously been reported in the United States. Twenty-one species are potential plant pathogens, 37 species are wood decay fungi. Twenty-four taxa appear to be previously unknown.
The origins of the wood pieces have not been revealed by the sellers. The scientists believe wood might have come from China, Vietnam, Thailand, and possibly other Asian countries.
Blanchette et al. note that many fungal-like pathogens that have caused devastating diseases in North American forests came from Asia, although not all were introduced directly from there. They name as examples chestnut blight, white pine blister rust, Dutch elm disease, Port-Orford cedar root disease, sudden oak death, and laurel wilt. [Brief descriptions of all these diseases can be found here.] These past introductions occurred via transport of soil, timber, wood products, living trees, or other plant material.
Blanchette et al. cite Smith et al. regarding detection of novel fungal pathogens of both plants and people on imported wooden handicrafts. They cite Brasier, Jung, and others for the likely Asian origins of many Phytophthora species (see citations at the end of this blog). They note the risk associated with the many undescribed species found in that region. In agreement with many others, Blanchette et al. suggest that fungal pathogens pose a very high risk for the U.S. due to rapid emergence of new diseases, low resistance in host populations, and limited surveillance infrastructure for detection.
The Blanchette et al. study was prompted by detection of Xylaria apoda growing on wood submerged in aquariums located in two states which are quite far from each other – Minnesota and Colorado. Despite the pieces of wood having been dried, shipped and stored for a long period during the import process, the fungus remained viable and was producing fruiting bodies. In total, they isolated eight species as known pathogens of agricultural crops and trees. They also report other fungi that might have potential to be plant or human pathogens. Blanchette et al. express specific concerns about possible impacts of the saprophytic taxa on ecosystem functions. That is, wood decay communities could be adversely affected by changes to biomass degradation and native wood-inhabiting insects.
Blanchette et al. point out that their detections came from 44 samples, which represent a very small fraction of the wood being imported for these purposes. Nevertheless the researchers detected impressive quantities and diversity of viable fungi.
Although they did not isolate any Oomycota species, Blanchette et al. say the presence of mud and soil indicates this type of wood could be a pathway for introduction of various exotic Phytophthora – which reside in aquatic and wet soil environments. They call for additional sampling and investigation using more selective methods of isolating Phytophthora species to determine if this could be a successful avenue for importing species of plant pathogenic Oomycota.
Blanchette et al. recommend that people who purchase wood for aquaria repeatedly soak and rinse the wood in water before putting it into an aquarium. This helps eliminate some of the heartwood extractives from the tropical woods and reduces water discoloration in aquariums, as well as possible toxicity to fish and plants. They warn that disposal of the water in contact with this wood into waterways or outdoors could easily release fungal species or Phytophthora spp. that might be in the wood.
Blanchette et al. say their results support earlier indications that current regulations to prevent the importation of non-native fungi on decorative woods used in aquariums are ineffective. In this investigation alone, they cultured more than 100 different live taxa that survived any fumigation or sterilization treatment. They note that scientists have repeatedly called for stronger phytosanitary regulations on imported wood.
One important step they suggest is increasing biosurveillance at the global level. They also suggest prohibiting importation of fungi and fungal-like organisms via this pathway before they become serious problems in their new environment. I concur with these suggestions – with the caveat that while the importation ban is in effect, APHIS and other agencies with authority over invasive species threats to non-plant resources should assess the risks and identify what steps each should take to address them.
[For the history of earlier critiques of weak regulation of imported wood, see blogs on this site under the category “wood packaging” and Fading Forest reports Two and Three (links at the end of this blog). For my critique of regulation of pathogens, see here or contact me.
SOURCES
Blanchette, R.A., Rajtar, N.N., Lochridge, A.G. et al. 2025. Intercontinental movement of exotic fungi on decorative wood used in aquatic and terrestrial aquariums. Scientific Reports 15, 9142. https://doi.org/10.1038/s41598-025-94540-x
Smith, J.A., T. Quesada, G. Alake, N. Anger. 2022. Transcontinental Dispersal of Nonendemic Fungal Pathogens through Wooden Handicraft Imports. mBio July/August 2022 Volume 13 Issue 4 10.1128/mbio.01075-22
Background sources
Brasier, C. M. 2008. The biosecurity threat to the UK & global environment from international trade in plants. Plant Pathol. 57, 792–808.
Brasier, C. M., Vettraino, A. M., Chang, T. T. & Vannini, A. 2010. Phytophthora lateralis discovered in an old growth Chamaecyparis forest in Taiwan. Plant. Pathol. 59, 595–603.
Jung, T., B. Scanu, C.M. Brasier, J. Webber, et al. 2020. A survey in natural forest ecosystems of Vietnam reveals high diversity of both new & described Phytophthora taxa including P. ramorum. Forests 11, 93.
Jung, T., Horta Jung, M.; Webber, J.F. et al. 2021. The destructive tree pathogen Phytophthora ramorum originates from the Laurosilva forests of East Asia. J. Fungi 7, 226.
Jung, T., Milenković I, Balci Y, et al. 2024 Worldwide forest surveys reveal forty-three new spp in Phytophthora major clade 2 with fundamental implications for the evolution & biogeography of the genus & global plant biosecurity. Stud. Mycol. 107, 251-388.
Roy, B. A. et al. 2014. Increasing forest loss worldwide from IAS pests requires new trade regulations. Front. Ecol. Environ. 12, 457–465.
Wingfield, M. J., Brockerhoff, E. G., Wingfield, B. D. & Slippers, B. 2015. Planted forest health: The need for a global strategy. Science 349, 832–836.
Posted by Faith Campbell
We welcome comments that supplement or correct factual information, suggest new approaches, or promote thoughtful consideration. We post comments that disagree with us — but not those we judge to be not civil or inflammatory.
For a detailed discussion of the policies and practices that have allowed these pests to enter and spread – and that do not promote effective restoration strategies – review the Fading Forests report at https://treeimprovement.tennessee.edu/
Erythrina caffra one of the native tree species in South Africa killed by PSHB. photo by Coana/Riti via Flickr
Introductions of bark and ambrosia beetles (Coleoptera: Curculionidae, Scolytinae) have significantly increased over the past century. Surveys conducted at borders and ports of entry around the world have shown the majority of beetles intercepted were scolytines. These insects are highly destructive on their own. Also, they can carry pathogenic fungal symbionts that can have devastating effects on the trees they attack.
One or more species in a complex in the Euwallacea genus have become established in countries around the world. One of these, the polyphagous shot hole borer (Euwallacea fornicatus; PSHB) and its associated fungus (renamed from Fusarium euwallaceae to Neocosmospora euwallaceae) is threatening havoc in South Africa about a decade after its establishment (Townsend, Hill, Hurley, and Roets. 2025).
Over this brief period PSHB/Fusarium disease has spread from two introduction sites – Pietermaritzburg, in KwaZulu-Natal Province, and Cape Town, in Western Cape Province – to all but one of the country’s nine provinces. It has become established in four of five forest types studied – Afrotemperate, coastal, sand, and swamp forests. It has not established in mangrove forests. (The Western Cape Province is home to its own “floral kingdom”. The kingdom’s charactersitic fynbos flora is a heathland habitat, not a forest one.)
Townsend and colleagues established a network of 78 monitoring plots in the Western Cape and KwaZulu-Natal provinces. The sites reflected a variety of natural and human impacts.
tree infested by PSHB/Fusarium disease in KwaZulu-Natal Botanical Garden, Pietermaritzburg. Photo from website of Greenpop.org
By monitoring these plots over five years (2019 – 2024), Townsend and colleagues have demonstrated that the beetle/fungus complex and resulting “Fusarium disease” is spreading and intensifying. The number of infected trees rose from 100 to 176 over the five years – a mean increase of 0.6% per year. The number of PSHB entry holes increased by over 10% annually. The number of plots containing infected trees roughly doubled from 23 in 2019 (29% of the 78 plots) to 48 (60%) in 2023.
By the end of the study, 29% of the 148 species sampled had been infected. This represented 43 species and 7 unidentified trees infected. Trees of eight native species died, , although one — Diospyros glabra (Ebenaceae) – resprouted after the main bole died.
In addition to the eight species known to suffer mortality, another 18 species were found to be able to support PSHB reproduction. Townsend and colleagues worry that, as the infestation spreads and intensifies, some of these species might also succumb. They mention specifically Erythrina caffra (coral tree), which is prevalent in coastal forest ecosystems across South Africa.
Most of the hosts are in the same families as those identified earlier by Lynch et al. (2021), e.g., Ebenaceae, Fagaceae, Fabaceae, Malvaceae, Podocarpaceae, Rutaceae, Sapindaceae and Stilbaceae.
Disease progress, speed of death, and visibility of symptoms varied not only between species, but sometimes among individuals of the same species. Some trees died rapidly. Townsend and colleagues say it is impossible to predict which individuals will succumb to infection.
There is, though, a clear frequency-dependent relationship between trees and beetles. Sites with higher relative abundance of host trees also had a higher proportion of infected trees, on average. The number of PSHB holes per species and per plot both increased to a larger extent at these same sites.
Individual trees’ traits influenced the severity of infestations (measured by the number of PSHB entry holes). Larger trees, those with a less healthy canopy, and those farther from a water source suffered more attacks. (This last finding differs from others’; Townsend et al. speculate that in the absence of flood-stressed trees, drought-stressed trees might be more attractive to ambrosia beetles.)
native tree in Tsitsikama National Park; photo by F.T. Campbell
Characteristics of the monitoring plots also affected disease progression. Higher proportions of trees became infected when they grew in plots that were closer to source populations, or that contained a higher proportion of host species as distinct from non-host species. The proportion of trees infected decreased in plots with higher tree densities or tree species richness.
As of 2023, “Fusarium disease” is more widespread and intense in KwaZulu-Natal than in the Western Cape. In KwaZulu-Natal 0.11% of monitored trees are infected compared to 0.06% in the Western Cape. The number of infected trees rose twice as fast over the five years in KwaZulu-Natal – ~6%, than in Western Cape – 3%. While all KwaZulu-Natal plots contained infected trees, three of 11 monitoring sites in the Western Cape did not. Townsend and colleagues believe that the most likely explanation is that PSHB arrived in KwaZulu-Natal earlier (as far back as 2012 as opposed to 2017 in Western Cape). Another possible factor is that source populations of infected trees are indigenous trees within the forest in KwaZulu-Natal whereas, in the Western Cape, they are often non-native trees planted in urban areas far from the study plots. Also, forests in KwaZulu-Natal are fragmented while, in Western Cape, the study forests are nearly contiguous. Townsend et al. conclude that the disease will spread and intensify in Western Cape as additional source populations become established in the forest.
locations of PHSB/Fusarium disease in Cape Town, South Africa – West of the study sites; map from City of Cape Town
As of 2023, the proportion of trees infected appears to be small — 7.6% of the 2,313 trees monitored. Only 11 trees in the monitored plots have died. However, the longer PSHB is active in the environment the more trees it will infest, the higher its impact will be on hosts, and the higher the number of dispersing individuals produced. This will substantially increase the chances and rates of additional areas becoming infected, especially in areas close to infestations – e.g., cities. They fear that in the future impacts will increase as progressively more competent host individuals are infected. Therefore, they emphasize the importance of mitigating PSHB increase in natural ecosystems, even in already infected areas.
Townsend and colleagues urge phytosanitary officials and resource managers to prioritize surveillance and management on the families containing several host species (above) and within plant communities in which they predominate. Managers must also be alert to new reproductive hosts for the beetle that appear as the infestation spreads and intensifies.
The situation could be worse than described; the Townsend et al. study did not examine how the invasion might affect eco-regions outside these two provinces. Because the PSHB has such a broad host range, hosts can die quickly, and South Africa provides ideal climatic conditions, this bioinvader could cause severe ecological effects on most indigenous forest types as well as agriculture and urban trees throughout Africa.
SOURCES
Lynch, S.C., A. Escalen, and G.S. Gilbert. 2021. Host evolutionary relationships explain tree mortality caused by a generalist pest-pathogen complex. Evol Appl 14:1083 – 1094. https://doi.org/10.1111/eva.13182
Townsend, G., M. Hill, B.P. Hurley, and F. Roets 2025. Escalating threat: increasing impact of the polyphagous shot hole borer beetle, Euwallacea fornicatus, in nearly all major South African forest types. Biol Invasions (2025) 27:88 https://doi.org/10.1007/s10530-025-03551-2
Posted by Faith Campbell
We welcome comments that supplement or correct factual information, suggest new approaches, or promote thoughtful consideration. We post comments that disagree with us — but not those we judge to be not civil or inflammatory.
For a detailed discussion of the policies and practices that have allowed these pests to enter and spread – and that do not promote effective restoration strategies – review the Fading Forests report at https://treeimprovement.tennessee.edu/
