Emerald Ash Borer

Emerald Ash Borer

In the summer of 2002, scientists realized that widespread damage to ash (Fraxinus) in southern Michigan was caused by an introduced insect, the emerald ash borer (Agrilus planipennis) (Federal Register, October 14, 2003, Volume 68, Number 198). The pest is thought to have been established in Michigan for at least 10 years by the time of its discovery (Siegert, 2006) and had already infested a large area in Michigan and adjacent Ontario. An invasion of European Russia (Moscow) was detected almost simultaneously in 2003. Both invasions probably originated from a common source in the late 1980s (Musolin et al. 2022). Due to a combination of factors, including both the biological and human dimensions of infestation and dispersal pathways, the pest has spread widely in both North America and Europe.

The emerald ash borer is indigenous to Asia and known to occur in China, Korea, Japan, Mongolia, the Russian Far East, and Taiwan. It was likely introduced from the Chinese range into North America in wood packaging; USDA APHIS has intercepted the insect 36 times at ports in eleven eastern states. Those shipments originated from at least eleven countries (Federal Register: October 14, 2003 (Volume 68, Number 198)). In recent years, no emerald ash borers have been intercepted; their family (Buprestidae) is currently detected considerably less frequently in wood packaging than are the longhorned beetles (Cerambycidae) (Wu et al. 2017). This may be because the debarking standard within the international regulation on the movement of wood packaging material, ISPM15, physically eliminates most of the phloem (the layer of the tree where EAB larvae feed), whereas Cerambycids typically are within the mechanically unaffected heartwood part of wood packing material.

The North American EAB population was most likely the result of a single introduction from China, probably the region of Hebei province and Tianjin City. The EAB population in Japan has been placed by one authority in the same species, A. planipennis. However, a more detailed analysis of genetic variations has led others to conclude that it should continue to be considered a separate species, A. marcopoli ulmi (Bray et al. 2011). Apparently no one has analyzed whether the genetic differences found in the Japanese entity – whether or not it is a separate species — might enable it to pose a significantly different threat to Fraxinus or other possible hosts in North America.

Eradication is no longer feasible for the emerald ash borer in North America. In January 2021, USDA APHIS terminated the domestic regulatory program it had implemented since 2003. At that time, 1,198 counties in 35 US states were released from the federal EAB regulation (EAB Manual 2020). The 2021 domestic deregulation does not affect the international movement of materials; federal regulations put in place in 2008 continue to restrict importation of ash wood and nursery stock from Canada.

Current programs by states and provinces focus on curtailing human facilitated spread of the insect by regulating the movement of infested materials. These state-based programs are complemented by federal research programs focused on long-term control measures, including biological control. Four biological control agents have been introduced to more than 30 states and have established in at least 22. Learn more at the USDA APHIS EAB main page.

North American EAB Infestation Overview

Within North America, the continued geographic spread of the now widely established EAB has historically been aided by the movement of both nursery stock and firewood. Firewood has been implicated as the source of dozens of infestations and remains an ongoing problem. Infestations assumed or shown to be caused by firewood are often found in or near campgrounds and homes heated with wood; these include the initial infestations identified in Missouri, Indiana, Colorado and West Virginia. Shipments of infested nursery stock were most problematic in the earlier years of the continent’s infestation, and caused the Maryland infestation as well as several others in the upper Midwest.

As of 2024, EAB is found in 37 states and 6 Canadian provinces. Several times outbreaks have emerged at sites hundreds of miles from the nearest known location. Recent examples of this include the first detection of EAB in Oregon in June 2022, and the first detection of EAB in North Dakota and British Columbia in 2024 . These “jumps” indicate that infested wood continues to be moved despite state regulations, international regulations, and extensive outreach campaigns.

West coast states have been trying to prevent EAB’s arrival. In Oregon, the Departments of Forestry and Agriculture, plus other entities, actively participated in the “Don’t Move Firewood” campaign for at least a decade. Oregon also established a broad quarantine that includes EAB (Williams, pers. comm.) California had been inspecting incoming shipments of firewood for years. In April 2021 – after APHIS terminated the federal quarantine on EAB – the California Department of Food and Agriculture (CDFA) established a state quarantine on the beetle and articles that could transport it into the state. In doing so, CDFA noted that commercially grown olive trees might also be at risk to EAB. Washington State operates a statewide trapping program for invasive insects. Attention has apparently focused on threats to urban forests. In 2016 the Washington Invasive Species Council carried out a study, with involvement of the Washington Department of Natural Resources Urban and Community Forestry Program as well as statewide stakeholder meetings (Bush, pers. comm.).

New outbreaks and infestations of emerald ash borer are announced sporadically. To find current information on locations in North America (and the status of each state, province, and county), it is best to go to Emeraldashborer.info or access their current map, which is typically updated on a monthly basis. Canadian provinces are also included on this location map, with confirmed infestations now ranging from New Brunswick to Manitoba. In general, EAB infestations in North America are slowly advancing westward.

European EAB Infestation Overview

In Europe, EAB has established in two provinces in Ukraine as well as 18 oblasts and several cities in European Russia, primarily to the west of Moscow towards the borders with Belarus and Ukraine (Musolin et al. 2021; Musolin et al. 2022). In Moscow, initial damage was greatest on the introduced North American species, green ash (Fraxinus pennsylvanica); however, by 2021 mass mortality was observed to European ash (F. excelsior) as well (Volkovitsh, Bienkowski and Orlova-Bienkowskaja, 2021).

The Russian populations have also experienced “jumps” of 400-500km, although firewood is considered a minor pathway compared to hitchhikeng on vehicles or drafting on vehicle wakes. In 2019, EAB was detected in southwest Russia and eastern Ukraine; this infestation might reflect widespread planting of F. excelsior and F. pennsylvanica along roads, railways, field shelter belts, and urban forests (Musolin et al. 2021). The second disjunct population is near St. Petersburg, only 130km from the borders of Estonia and Finland; it was detected in September 2020. This northern population has spread more slowly, possibly due to the longer life cycle associated with the colder climate. However, ash grows in continuous stretches from both the southern (Davydenko et al. 2022) and northwestern area into central Europe. Musolin et al. (2022) cite a separate analysis in stating that EAB can probably invade most European countries. Davydenko et al. (2022) think the EAB could virtually eliminate European ash (F. excelsior) from much of the continent, although it is less vulnerable than F. pennsylvanica.

Emerald Ash Borer Feeding and Host Trees

EAB larvae feed in the phloem and outer sapwood, producing galleries that damage and eventually kill the host. Adult EAB feed on host foliage. In its native range in east Asia, the pest feeds on species of Fraxinus (ash), Ulmus (elm) and Juglandaceae (walnuts and hickories) (McCullough & Roberts, 2002a and 2002b). In North America, the borer feeds primarily on Fraxinus species, although it will also infest Chionanthus virginicus, fringtree and has been experimentally shown to infest Olea europea, Olive tree (see section below). All North American ash trees (Fraxinus) are attacked by EAB; the insect shows a high degree of preference for green (F. pennsylvanica) and black (F. nigra) ash, lower preference for healthy blue ash (F. quadrangulata), and appears to have a relatively complex interaction with white ash (F. americana) (Robinette and McCullough, 2019).

Fraxinus as EAB Hosts

USFS scientists and managers developed a conservation priority-setting framework for forest tree species at risk from pest & pathogens and other threats. The Project CAPTURE (Conservation Assessment and Prioritization of Forest Trees Under Risk of Extirpation) uses FIA data and expert opinion to group tree species under threat by non-native pests into vulnerability classes and specify appropriate management and conservation strategies. The scientists prioritized 419 tree species native to North America. The analysis identified 15 priority taxonomic groups requiring immediate conservation intervention due to their exposure to an extrinsic threat, their sensitivity to that threat, and their ability to adapt to it. Each of these 15 most vulnerable species, as well as several additional species, should be the focus of both a comprehensive gene conservation program and a genetic resistance screening and development effort.

Carolina ash (Fraxinus caroliniana) and pumpkin ash (F. profunda) are among six species that face severe pest threats but have a high capacity to adapt (according to CAPTURE project). For this reason, conservation and the facilitation of resistance through breeding are high priorities. Several other ash species that have not yet been infested by EAB may eventually experience extensive mortality, and because they tend to be rare, CAPTURE ranked them high for conservation and the facilitation of resistance. Such species include Texas ash (Fraxinus albicans), velvet ash (F. velutina), Chihuahua ash (F. papillosa), fragrant ash (F. cuspidata), Berlandier ash (F. berlandieriana), and Gregg ash (F. greggii).

In Ohio (Knight et al. 2020) blue ash trees have remained healthy after two decades of EAB presence, but no black ash with > 10cm dbh is healthy. Levels of health are intermediate for other species. Surviving ash constitute less than 1% of trees with dbh >10cm; at some sites there are none. Up to 61% of the “lingering” ash eventually die. This is expected. It demonstrates the importance of increasing resistance levels by breeding and continuing to deploy other strategies.

Many ash seedling and saplings are surviving and growing in fragmented forests of Ohio. In the large swath of contiguous forest of the Allegheny National Forest there is almost no ash regeneration (Knight et al. 2020). In an experiment, Dr. Knight is defining what proportion of ash trees on the forest should be protected by chemical treatments to conserve the full genetic diversity present there. Funding to continue the treatments is uncertain.

As noted above, EAB has been introduced to the range of Oregon ash (Fraxinus latifolia). Oregon ash is a wide-ranging species, occurring from California to Washington and possibly into British Columbia. It is an important component of riparian forests. In wetter parts of the Willamette Valley, ash dominates these systems; for example, the riparian forest in the Ankeny National Wildlife Refuge is nearly 100% Oregon ash (ODA/ODF EAB Response Plan).

As is true in the Midwest, ash provides important food and habitat resources along creeks and rivers where seasonally high water-tables can exclude nearly all other tree species. Standing and fallen dead ash biomass can alter soil chemistry and affect rates of decomposition, nutrient, and water cycling, (i.e., nutrient resource availability for the remaining trees). Gaps in tree canopy can increase soil erosion, storm water runoff and elevated stream temperatures. In dense stands of Oregon ash, understory vegetation is often sparse, consisting primarily of sedges (ODA/ODF EAB Response Plan).

California has two native ash trees. Oregon ash (Fraxinus latifolia) occurs naturally from southern British Columbia to southern California. According to the California Native Plant Society, F. latifolia is found in riparian mixed forests of the Great Valley; although it is rare in the Sacramento-San Juaquin River delta. https://vegetation.cnps.org/alliance/32 The second species, velvet ash (F. velutina), is found in the south, including the southern Sierra Nevada, Mojave and Colorado Deserts, and the California chaparral and woodlands ecoregion. Ash species are also planted in urban forests. Significant densities of planted ash are found in the Sacramento – Davis area, and down the center of the Central Valley through Fresno to Bakersfield. See map of California’s Native Trees.

In Eastern Ukraine, where EAB has been introduced to areas already infected by the invasive ascomycete fungus Hymenoscyphus fraxineus (cause of ash dieback, ADB), F. excelsior has been found to be more resistant to EAB than F. pennsylvanica, but more susceptible to ADB. Davydenko et al. (2022) conclude that ADB facilitates EAB attack on F. excelsior trees. Some F. excelsior trees had survived both non-native pests. Davydenko et al. (2022) suggested these trees might constitute a source of material for eventual propagation. However, the war now under way in these regions must have forced a halt to any such exploration.

Fringetrees and Olives as EAB Hosts

EAB is also known to attack another, related, genus of trees: fringetrees (Cionanthus spp.). EAB attacks on fringetrees were first noticed by Dr. Don Cipollini of Wright State University in Ohio in 2014 (Hannah, 2014). Initially, it was uncertain whether EAB could establish in the Cionanthus genus. However, by summer 2015, Dr. Cipollini demonstrated that EAB attacked fringetrees across a wide area – including much of Ohio and parts of Illinois. EAB attacks on fringetrees appear to occur when EAB populations are high (Entomology Today, 2015). This could have implications for the white fringetree (C. virginicus) which is native to North America. Wild populations of C. virginicus grow from New Jersey south to Florida and west to Texas; it has also grown in popularity as an ornamental plant in a wider area of the country. In laboratory and field studies, Callahan (2024) found that in white fringetree, most EAB larvae died in 1st or 2nd instar – before a suitable stage for parasitism by one of BC agents, Spathius agrili. EAB can mature on fringetrees, but it is doubted that they will do so in sufficient numbers to serve as a reservoir for EAB (Callahan, 2024).

After the EAB was detected on white fringetree, scientists began exploring whether it might also attack another species in the same family, olive trees (Olea europaea) cultivated for fruit and oil. In a series of experiments, Dr. Cipollini demonstrated that EAB larvae grow more slowly on olive stems, but they can reach the prepupal stage, at least when the trees are large (18 cm diameter at base) and had grown in orchards for several decades. On young trees with diameters of 3 cm or less, most EAB larvae died (Cipollini, D. Powerpoint; Peterson et al. 2020).

Several factors probably influence the likelihood that EAB will oviposit on olive trees, and the impact of such an attack. Adult EABs must feed on trees’ leaves for 10 days or more before they can mate and lay eggs. Unlike the thin deciduous leaves of ash, olive trees’ foliage is evergreen, xerophytic, and tough (Peterson et al. 2020). Olive leaves also contain much higher concentrations of oleuropein, a phenolic compound that when present in high is concentrations is toxic to insects. There is considerable variation in levels present in any particular tree — depending on the environment, season, and the variety of the olive tree. Levels also vary between tissues, e.g., leaf or phloem. Finally, the level of stress experienced by the tree probably also plays a role, although this factor has not been studied (Cipollini, D. Powerpoint).

In one study, Peterson et al. (2020) found that while adult EAB feed readily on olive foliage, more than 50% died by day 10, that is, the time when most females complete maturation feeding and begin to mate. By day 18, 90% of adults consuming olive leaves were dead. In this study, only three eggs were laid by adult EAB. In addition, as noted above, EAB larvae also find olive trees to be challenging.

Still, while olive is a suboptimal host, larval performance on olive is similar to or better than its performance on its native host, Manchurian ash (Fraxinus mandschurica) (Cipollini and Peterson, 2018). Some females lived long enough to oviposit; they produced viable eggs, and at least one of the eggs hatched into an apparently healthy and vigorous larva (Peterson et al. 2020). They conclude that EAB could subsist at some level on olive in orchards where beetle populations are high. Furthermore, since larvae apparently can reach adulthood on living olive stems, EAB might evolve greater tolerance of oleuropein and thus improve their ability to utilize olive as a host (Peterson et al. 2020).

The presence of ash near olive orchards would exacerbate the damage, and might be necessary to support sufficient EAB populations. Olive production in California is concentrated in Tulare County, with additional orchards in the northern Sacramento Valley and Kings County (which neighbors Tulare County) (CDFA and REP 2016). Some of the native and planted ash populations might overlap regions supporting olive groves in some of these areas.

In laboratory tests, a few EAB larvae also survived in the more distantly related devilwood tree (Osmanthus americanus). EAB did not, however, survive in the Chinese fringetree (Chionanthus retusus). Since Chinese fringetree is native to the same parts of China as is EAB, it may have evolved chemicals that protect it from the insect (Entomology Today, 2015). While the newly discovered ability of EAB to infest fringetrees may not extend the geographic area that is vulnerable to invasion, it will increase the amount of trees killed as well as the associated economic and ecological damage. For example, in Missouri and Arkansas, white fringetree is one of the few trees or shrubs that grows on bald knobs and limestone/dolomite glades (LeDoux, 2014).

The Future of North American Ash Trees

Ash trees are important members of deciduous forests, riparian and wetland vegetation across North America and are co-dominants (for example with maples [Acer] and beeches [Fagus]) in some ecological communities. (In bottomland communities, American elm, Ulmus americana, was at least a co-dominant species before succumbing to invasion by introduced Dutch elm disease pathogens). There are seventeen ash species in North America north of Mexico (Kartesz, 1994), and it is possible the emerald ash borer will attack them all, although susceptibility apparently varies (Haack et al. 2004; McCullough, 2004). Ashes are particularly important components of rich, mesic woodlands, cove forests, swamps, floodplain and bottomland forests (Wagner, 2007) – all habitats harboring exceptional biodiversity. Wagner (2007) lists 21 species of North American butterflies and moths (lepidopterans) believed to be specialists or largely dependent on ash that he fears might be extirpated if the emerald ash borer kills all ash on the North American continent. He expresses concern for additional species that feed, in part, on other genera. Ash trees that dominate riparian forests on the Pacific slope as well as the southwestern deserts could also suffer high mortality rates. Wagner (2007) notes that little is known about the lepidopteran associates of these western ash.

Ongoing federal efforts to strengthen the resilience of ash across North America now focus on biocontrol and breeding. Ash species that co-evolved with EAB in its native range (e.g., F. chinensis and F. mandshurica) are naturally more resilient to the pest and thus may provide a source of genes for resistance breeding (Herms and McCullough, 2014). A recent study by Kelly et al. (2020) sought to determine the genes involved in EAB resistance across the Fraxinus genus and searched for evidence of co-evolution by assessing resistance in 26 Fraxinus species. They found six resistant taxa (all native to Asia), several of which are close enough in relation to the three most vulnerable North American species (F. pennsylvanica, F. americana and F. nigra) to allow the validation of any candidate genes identified (Kelly et al. 2020). Kelly et al. (2020) also searched for, and successfully identified EAB resistant variants in a large pool of genetically diverse F. excelsior; this means that researchers may be able to use marker assisted selection to accelerate breeding and match variants with different resistant genes, thus improving resistance in the progeny. Efforts are now under way to find resistant variants in a diverse population of the North American native, F. nigra (Dr. Jennifer Koch, personal communication September 2021).

In fact, attempts to amplify resistance in multiple species of native North American ash are well under way. While monitoring ash die offs, Knight et al. (2012) found a small percent of ash populations survived heavy EAB infestation. It was hypothesized that these remaining or “lingering” ash trees likely survive, at least in part, due to a natural genetic advantage resulting in a higher tolerance or resistance to EAB infestation (Koch et al. 2015). Through their efforts to preserve and study lingering ash, Koch and colleagues (2015) found that lingering green ash were less preferred by adult EAB feeding and harbored less larval survival than susceptible controls.

Recent research has confirmed the efficacy of breeding for higher resistance by using 42 selected lingering ash and grafted replicates of a lingering ash progeny; the crossing demonstrated the genetic heritability of EAB resistance in green ash, since lingering ash parents produced a higher frequency of resistant progeny – with some progeny expressing stronger resistance than the parents (Stanley et al., 2021). Further, partial resistance has been identified at higher frequencies in blue and black ash, which means researchers may forego waiting for large die-offs to reveal lingering ash in these species and, instead, can select candidates by using open-pollinated seedlings (Dr. Jennifer Koch, personal communication Sept. 2021). Cumulatively, research suggests that more than one mechanism is likely responsible for increased EAB resistance, and selective breeding to enhance resistance shows promise as a powerful conservation strategy for native ash (Koch et al. 2015; Romero-Severson and Koch, 2017; Stanley et al., 2021). The precedence for success is evident in similar breeding programs to improve resistance against vectors that cause pathoses including fusiform rust and blister rust diseases, Port-Orford-cedar root disease, and beech bark disease (Pike et al. 2021).

Ultimately, a combination of biological and cultural control techniques will provide the best defense against invasive pests that are established in North America, including EAB. Long term monitoring of host and pest populations along with diligent preventative measures to limit new infestations are crucial components of the integrated pest management framework needed for the EAB problem in North America and beyond (Knight et al. 2020).

In Oregon, the state departments of Forestry and Agriculture led preparation of an EAB response plan. It details the roles of both government agencies and non-governmental stakeholders. Oregonians also began laying the groundwork for resistance breeding program in 2019, before the EAB was detected. With funding from the USDA Forest Service Forest Health Protection program and a Soil and Water Conservation District, and cooperation by the USDA Forest Service Dorena Genetic Resource Center (located in Cottage Grove, Oregon), Bureau of Land Management units, Oregon State University, citizen scientists and the Oregon Department of Forestry [press release & Sneizko pers. comm.] began collecting seed from the ash range in Oregon. This project has now been expanded to include Washington State University at Puyallup Research & Extension Center, and Huntington Botanical Gardens in San Marino, Los Angeles County. Both the USFS Dorena Center and Washington State University have begun germinating and growing some of the seedlings for various tests of possible resistance. (Chastagener pers. comm.)

Testing whether some of the ash seedlings show genetic resistance to EAB is being conducted at USFS research site in Ohio, where EAB is well established.

For more information on this pest, please consult:

• USDA APHIS Plant Health Emerald Ash Borer Program Page
• Emeraldashborer.info
• Emerald Ash Borer Manual, USDA APHIS 2020
• Federal Deregulation of Emerald Ash Borer, blog 2020
• Natural Resources Canada Emerald Ash Borer Page
• Multi-state Emerald Ash Borer Insecticide Fact Sheet
• Present State, Use and Perspectives of Gensus Fraxinus in Mexico (2010)

Sources

Entomology Today https://entomologytoday.org/2015/07/22/emerald-ash-borer-infestation-of-white-fringetree-found-to-be-widespread/ accessed 8/12/15

The Federal Register. October 14, 2003 (Volume 68, Number 198). Emerald Ash Borer; Quarantine and Regulations (available by using search engines/retrieval services at https://www.gpoaccess.gov/fr/index.html).

The Federal Register. December 15, 2020 (Volume 85, No.241). Removal of Emerald Ash Borer Domestic Quarantine Regulations (available by using search engines/retrieval services at https://www.gpoaccess.gov/fr/index.html).

Bray, A. L.S. Bauer, T.M. Pol, R.A. Haack, A.I. Cognato, and J.J. Smith. 2011. Genetic analysis of emerald ash borer (Agrilus planipennis Fairmaire) populations in Asia and North America. Biol Invasions (2011) 13:2869–2887 DOI 10.1007/s10530-011-9970-5

Bush J. Executive Coordinator | Washington Invasive Species Council

Callahan, H. 2024. Emerald ash borer host range expansion and natural enemy responses: implications for biocontrol. 32nd USDA Interagency Research Forum on Invasive Species. January 9 – 12, 2024. Annapolis, Maryland

CDFA and Fertilizer Research & Education Program. 2016 https://apps1.cdfa.ca.gov/FertilizerResearch/docs/Olive_Production_CA.pdf

Cipollini, D. Powerpoint “Emerald ash borer and cultivated olive: what are the chances?”

Cipollini, D. and D.L. Peterson. 2018. The potential for host switching via ecological fitting in the emerald ash borer-host plant system. ecologia (2018) 187:507–519 https://doi.org/10.1007/s00442-018-4089-3

Davydenko, K.; Skrylnyk, Y.; Borysenko, O.; Menkis, A.; Vysotska, N.; Meshkova, V.; Olson, Å.; Elfstrand, M.; Vasaitis, R. 2022. Invasion of emerald ash borer Agrilus planipennis & ash dieback pathogen Hymenoscyphus fraxineus in Ukraine-A concerted action. Forests, 13, 789

Ellison, E.A., Peterson D. L., and Cipollini, D. 2020. The Fate of Ornamental White Fringetree Through the Invasion Wave of Emerald Ash Borer and Implications for Novel Host Use by This Beetle. Environmental Entomology, 2020, Vol. 49, No. 2 493

GPTFII 2008. Emerald Ash Borer Fact Sheet. Great Plains Tree and Forest Invasives Initiative. June 2008.

Haack, R. A., T. R. Petrice, D. L. Miller, L. S., Bauer and N. M. Schiff. 2004. Host range of Emerald Ash Borer. p. 38 In V. Mastro and R. Reardon (compilers) Emerald Ash Borer research and technology development meeting, Port Huron Michigan, Sept 30-Oct 1, 2003. USDA Forest Service publication FHTET-2004-02.

Hannah, J. Wright State researcher finds emerald ash borer may have spread to different tree. October 9, 2014

Herms, D. A. & McCullough, D. G. 2014. Emerald ash borer invasion of North America: history, biology, ecology, impacts, and management. Annu. Rev. Entomol., 59: 13–30.

Hieftje, J. 2007. Continental Dialogue on Non-Native Forest Insects and Diseases Annual Meeting, Atlanta, GA January 2007.

Kartesz, J.T. 1994. A synonymized checklist of the vascular flora of the United States, Canada, and Greenland. Second edition. Timber Press. Portland, OR.

Kelly, L.J., Plubm, W.J., Carey, D.W., Mason, M.e., Cooper, E.D., Crowther, W., Whittemore, A.T., Rossiter, S.J., Koch, J.L., and Buggs, R.J. 2020. Convergent molecular evolution among ash species reistant to the emerald ash borer. Nature Ecology and Evolution, 4: 116-1128.

Koch, J.L., Carey, D.W., and Mason, M.E. 2015. Intraspecific variation in Fraxinus pennsylvanica responses to emerald ash borer (Agrilus planipennis). New Forests, 46: 995-1011.

Kovacs, K.F., R.G. Haight, D.G. McCullough, R.J. Mercader, N.W. Siegert, A.M. Liebhold. 2009. Cost of potential emerald ash borer damage in U.S. communities, 2009–2019. Ecological Economics. 2009.

Knight, K.S., Herms, D. Plubm, R. Sawyer, E. Spalink, D., Pisarczyk, E., Wiggin, B., Kappler, R., Ziegler, E., and Menard, K. 2012. Dynamics of surviving ash (Fraxinus spp.) populations in areas long infested by emerald ash borer (Agrilus planipennis). In: Sneizko, R.A., Ynachuk, A.D., Kliejunas, J.T., Palmieri, K.M., Alexander, J.M., and Frankel, S.J. (eds). Proceedings of the 4th International Workshop on Genetic of Host-Parasite Interactions in Forestry, USDA Forest Service Pacific Southwest Research Station, PSW-GTR-240, pp 143-152.

Knight, K., Kappler, R.H., Root, K.V., Koch, J.L., and Flower, C.E. 2020. Monitoring of ash mortality patterns informs emerald ash borer (EAB) resistance breeding efforts: Integrated pest management for EAB. In: Nelson, D.C., Koch, J.L., Sniezko, R.A. eds. Proceedings of the Sixth International Workshop on the Genetics of Host-Parasite Interactions in Forestry – Tree Resistance to Insects and Diseases: Putting Promise in to Practice. Gen. Tech. Rep. SRS-252. Asheville, NC: U.S. Department of Agriculture Forests Service, Sothern Research Station.

LeDoux, D. Missouri Department of Agriculture. Personal communication 2014.

Lucik, Sharon. 2010. Public Affairs Specialist, United States Department of Agriculture Animal & Plant Health Inspection Service, pers. comm. February 11, 2010.

McCullough, D. G., A. Agius, D. Cappaert, T. Poland, D. Miller and L. Bauer. 2004. Host range and host preference of Emerald Ash Borer. pp. 39-40 In V. Mastro and R. Reardon (compilers) Emerald Ash Borer research and technology development meeting, Port Huron Michigan, Sept 30-Oct 1, 2003. USDA Forest Service publication FHTET-2004-02.

McCullough, D. G., and D. L. Roberts. 2002a. Manuscript Draft for USDA Pest Alert on the emerald ash borer. Deborah McCullough at Department of Entomology, Michigan State University.

McCullough, D. G., and D. L. Roberts. 2002b. Emerald ash borer. Pest Alert. USDA Forest Service, Northeastern Area, State and Private Forestry, 2 pp. https://www.na.fs.fed.us/spfo/pubs/pest_al/eab/eab.pdf.

Musolin, D.L.; Kirichenko, N.I.; Karpun, N.N.; Aksenenko, E.V.; Golub, V.B.; Kerchev, I.A.; Mandelshtam, M.Y.; Vasaitis, R.; Volkovitsh, M.G.; Zhuravleva, E.N.; et al. 2022. Invasive insect pests of forests & urban trees in Russia: Origin, pathways, damage, & management. Forests, 13, 521.

Musolin, D.L., Selikhovkin, A.V., Peregudova, E.Y., Popovichev, B.G., Mandelshtam, M.Y., Brananchikov, Y.N., and Vasaitis, R. 2021. North-westward expansion of the invasive range of emerald ash borer, Agrilus planipennis Fairmaire (Coleoptera: Buprestidae) towards the EU: From Mosco to Saint Petersburg. Forests 2021, 12, 502. https//doi.org/10.3390/f12040502

Nowak, D.J. 2008. Money Matters: $ Facts about ash trees and EAB. Illinois Dept. of Natural Resources. https://dnr.state.il.us/conservation/forestry/Urban/Includes/MoneyMattersUpdate.htm, accessed August 2008.

Oregon Department of Forestry and Oregon Department of Agriculture Emerald Ash Borer Readiness and Response Plan. 2018.
https://static1.squarespace.com/static/58740d57579fb3b4fa5ce66f/t/5b1ad1896d2a73a4cffcdad1/1528484258046/EAB+Plan+2018.pdf

Oregon Department of Forestry press release Feb 24, 2022

Peterson, D.L., B. Slager, A.C. Anulewicz, and D. Cipollini. 2020. Feeding, Survival, & Fecundity of Adult Emerald Ash Borer (Coleoptera: Buprestidae) on Foliage of Two Novel Hosts & Implications for Host Range Expansion. Environmental Entomology, XX(XX), 2020, 1–8 doi: 10.1093/ee/nvaa046

Pike, C.C., Koch, J. and Dana Nelson, C. 2021. Breeding for resistance to tree pests: successes, challenges, and a guide to the future. Journal of Forestry, 119(1): 96-105.

Potter, K.M., Escanferla, M.E., Jetton, R.M., Man, G., and Crane, B.S. 2019. Prioritizing the conservation needs of US tree spp: Evaluating vulnerability to forest insect and disease threats, Global Ecology and Conservation, doi: https://doi.org/10.1016/

Robinett, M.A and D.G. McCullough. 2019. White ash (Fraxinus americana) survival in the core of the emerald ash borer (Agrilus planipennis) invasion. Can. J. For. Res., 49: 510-520.

Romero-Severson, J., and Koch, J.L. 2017. Saving green ash. In: Sniezko, R.A., Man, G., Hipkins, V., Woeste, K., Gwaze, D., Klejunas, J.T., and McTeague, B.A. (tech. crdntrs.) 2017. Proceedings of Workshop on Gene Conservation of Tree Species – Banking on the Future. May 16-19, 2016.

Siegert, N.W. 2006. 17th USDA Interagency Research Forum on Gypsy Moth and Other Invasive Species. Annapolis, MD. January 10-13, 2006.

Sniezko, R. 2022. USDA Forest Service, pers. comm. Feb 2022 22-2/24

Sniezko, R. 2021.. Treeline Newsletter May 13, 2021.Is There a Future for Oregon Ash? Forest Genetics to the Rescue? Genetic & Emerald Ash Borer Resistance Projects https://www.nnrg.org/wp-content/uploads/2022/02/Treeline_newsletter-June-2021.pdf
The newsletter is issued by Bonneville Environmental Foundation for a consortium of conservation agencies

Stanley, R.K., Carey, D.W., Mason, M.E., Poland, T.M., Koch, J.L. Jones, and A.D., Romero-Severson, J. 2021. Untargeted metabolomics and progeny tests reveal complex metabolite-based emerald ash borer resistance in Fraxinus pennsylvanica. New Phytologist, (submitted).

Stubbings, G. 2008. Dir. of Plant Health for the Canadian Food Inspection Agency. Personal communication, August 2008.

Treeline Newsletter May 13, 2021. Richard Sniezko. Is There a Future for Oregon Ash? Forest Genetics to the Rescue? Genetic & Emerald Ash Borer Resistance Projects https://www.nnrg.org/wp-content/uploads/2022/02/Treeline_newsletter-June-2021.pdf
The newsletter is issued by Bonneville Environmental Foundation for a consortium of conservation agencies.

USDA Animal and Plant Health Inspection Service. Emerald Ash Borer Cooperative Eradication Program in the Lower Michigan Peninsula, Environmental Assessment December 2003.

USDA Animal and Plant Health Inspection Service. 2007. Proposed Release of Three Parasitoids for the Biological Control of Emerald Ash Borer (Agrilus planipennis) in the Continental United States. Environmental Assessment. April 2, 2007.

Volkovitsh, M.G., Bienkowski, A.O., and Orlova-Bienkowskaja, M.J. 2021. Emerald ash borer approaches borders of the European Union and Kazakhstan and is confirmed to infest European ash. Forests, 2021, 12, 691. https://doi.org/10.3390/f12060691

Wagner, D.L. 2007. Emerald Ash Borer Threatens Ash-feeding Lepidoptera. News of the Lepidopterists’ Society, 49 (1).

Wu, Y., N.F. Trepanowski, J.J. Molongoski, P.F. Reagel, S.W. Lingafelter, H. Nadel1, S.W. Myers & A.M. Ray. 2017. Identification of wood-boring beetles (Cerambycidae and Buprestidae) intercepted in trade-associated solid wood packaging material using DNA barcoding and morphology. Scientific Reports, 7:40316