Invasive Species Information
The Emerald Ash Borer, Agrilus planipennis, Fairmaire (Coleoptera: Buprestidae), commonly referred to as "EAB", is an invasive wood-boring beetle. Native to Asia, the beetle's first North American populations were confirmed in the summer of 2002 in southeast Michigan and in Windsor, Ontario. EAB was likely introduced to the area in the mid-1990's in ash wood used for shipping pallets and packing materials in cargo ships or shipping containers. Emerald Ash Borers feed on and eventually kill all native ash trees (Fraxinus spp.). Slowing their spread is imperative.
Since its introduction into North America, 18 states (Connecticut, Illinois, Indiana, Iowa, Kentucky, Kansas, Maryland, Massachusetts, Michigan, Minnesota, Missouri, New York, Ohio, Pennsylvania, Tennessee, Virginia, West Virginia and Wisconsin) and two Canadian provinces; Ontario and Quebec. EAB was first confirmed in New York in June 2009 near Randolph, in western Cattaraugus County.
The natural spread of EAB infestations in North America is about 2 miles per year, depending on the infestation intensity. However, the rapid spread of the beetle through North America is most likely due to the transport of infested firewood, ash nursery stock, unprocessed ash logs, and other ash products. In an effort to slow the continued spread of EAB, both Federal and State agencies have instituted quarantines of infested areas to regulate the transport of ash products.
The Emerald Ash Borer (Agrilus planipennis) is an Asian wood-boring beetle in the family Buprestidae. This beetle was accidentally introduced to North America around the beginning of the 21st century (first noted in both Michigan, U.S.A., and Ontario, Canada, in 2002). Since then, it has killed millions of ash trees (Fraxinus spp.) in (at least) Michigan, Indiana, Illinois, Ohio, Pennsylvania, Maryland, West Virginia, and Wisconsin (U.S.A.) and Ontario and Quebec (Canada). Emerald ash borers colonize trees that range in size from saplings to fully mature trees. Larvae feed under the bark on phloem and outer xylem, girdling and killing trees within 1 to 4 years of colonization. Efforts to find one or more effective biocontrol agents are ongoing, but the potential ecological and economic costs of this pest are clearly enormous. (Poland and McCullough 2006; Duan et al. 2009; Gandhi and Herms 2010; Kovacs et al. 2010)
Regularity: Regularly occurring
Type of Residency: Year-round
The native range of the Emerald Ash Borer includes China, Japan, Korea, Mongolia, the Russian Far East, and Taiwan (Anulewicz et al. 2008 and references therein).
Anulewicz et al. (2008) carried out field experiments to examine the potential for Emerald Ash Borers in North America to expand their host range to include species other than ashes (Fraxinus spp.). In Asia, the Emerald Ash Borer seems not to be a major pest, generally occurring at low densities and attacking severely stressed or declining trees. In North America, however, where ash species have no co-evolutionary history with this insect, the Emerald Ash Borer has killed healthy, as well as stressed, Green Ash (F. pennsylvanica), White Ash (F. americana), Black Ash (F. nigra), and Blue Ash (F. quadrangulata). In Asia, Emerald Ash Borer has been reported to attack other hosts in addition to ashes, but attacks on non-ashes have not been reported for North America (although tens of millions of ash trees have been attacked). In field tests using several North American relatives of reported non-ash hosts from Asia, Anulewicz et al. found that, although Emerald Ash Borer adults would occasionally land on and oviposit on logs and trees of non-ash species, larvae did not successfully develop on anything other than ashes. (Anulewicz et al. 2008 and references therein)
Rebek et al. (2008) tested the resistance to Emerald Ash Borer of an Asian ash species, Manchurian Ash (Fraxinus mandshurica) and found that it was significantly less susceptible to Emerald Ash Borer attack than were tested North American ashes, suggesting the existence of targeted defenses resulting from a shared evolutionary history in their native Asia. Liu et al. (2007) reported that in China exotic North American species such as Green Ash are more susceptible to Emerald Ash Borer attack than are native Chinese ash species when planted at the same site.
Liu et al. (2007) studied two natural enemies of Emerald Ash Borer, Oobius agrili (Encyrtidae) and Tetrastichus planipennisi (Eulophidae), and found that both contribute significantly to Emerald Ash Borer population suppression on Green Ash in northeastern China. Previous studies showed that T. planipennisi was also an important mortality factor for Emerald Ash Borer on Manchurian Ash in China. Oobius agrili is a newly described solitary egg parasitoid of Emerald Ash Borer from China with no other known hosts. Although host resistance to Emerald Ash Borer differs between native Chinese ash species and species introduced from North America, the ability of these parasitoids to locate and attack Emerald Ash Borers apparently does not differ between Chinese and North American ashes. Based on the high observed parasitism rates, short generation times, high reproduction rates, and life-cycle synchronizations with their respective host stages, the authors suggest that these parasitoids may prove useful for biological control of Emerald Ash Borer in North America. (Liu et al. 2007 and references therein)
Yang et al. (2008) carried out no-choice tests to examine the potential host range of Spathius agrili (Hymenoptera: Braconidae), a braconid species described in 2005 that paralyzes Emerald Ash Borer larvae when it lays eggs on them, arresting their development, with newly hatched wasp larvae consuming the host beetle larva in 7 to 10 days (Yang et al. 2005). They found that although S. agrili can parasitize some other Agrilus larvae, observed attack rates were significantly lower than for its natural host, the Emerald Ash Borer.
Ulyshen et al. (2010) studied competitive interactions betwee two of the three hymenopteran parasitoids native to China that are being released in the United States as biological control agents for the Emerald Ash Borer, the larval ectoparasitoid Spathius agrili (Braconidae) and the larval endoparasitoid Tetrastichus planipennisi (Eulophidae) (the third species being released, Oobius agrili [Encyrtidae], is an egg parasitoid and therefore not expected to compete directly with the other two). Female S. agrili permanently paralyze their hosts by envenomation during oviposition and produce 1 to 18 offspring per host (mean 8.4); in China, they complete up to four generations a year and levels of parasitism range from 30% to 90%, with 1 to 35 eggs associated with a single host individual (Yang et al. 2005). Between 4 and 172 T. planipennisi offspring are produced per host (Uyshen et al. 2010). In contrast to larvae parasitized by S. agrili, host larvae parasitized by T. planipennisi remain active and continue to feed for about a week. After consuming the host larva, parasitoid larvae exit from the integument and pupate within the beetle gallery. Adult wasps eclose approximately 15 days after pupation and exit the tree through one or more holes chewed through the bark. In China, four or more generations are produced each year and observed levels of parasitism range from 0% to 65%, with 56 to 92 individuals developing in a single host larva (Liu et al. 2007; Yang et al. 2006). In competition trials, Ulyshen et al. (2010) found that S. agrili tended to excluded T. planipennisi, an observation they attribute to S. agrili being much more efficient at locating hosts. They also found that S. agrili parasitized larvae previously parasitized by T. planipennisi, although the reverse was not observed. However, S. agrili offspring failed to complete development on hosts that were previously parasitized by T. planipennisi. Ulyshen et al. (2010) suggested releasing these two species separately in time or space to avoid the antagonistic interactions observed in their study.
Although investigations of biocontrol options are focused on the use of parasitoids imported from China, Duan et al. (2009) surveyed the parasitoids currently attacking Emerald Ash Borer in western Pennsylvania. Five parasitoids were identified: Balcha indica (Eupelmidae), Eupelmus pini (Eupelmidae), Dolichomitus vitticrus (Ichneumonidae), and 2 ichneumonids identified only to genus, Orthizema sp. and Cubocephalus sp.. Together, these parasitoids parasitized 3.6% of the sampled Emerald Ash Borers (1,091 larvae, prepupae, and/or pupae). Balcha indica accounted for 82% of the parasitoids recovered. The association with Emerald Ash Borer of the two eupelmids, although not the ichneumonids, was confirmed in laboratory assays The authors suggest that these two eupelmid species may be complementary to the ongoing Emerald Ash Borer biological control efforts in the U.S., which include 1 egg and 2 larval parasitoids that attack Emerald Ash Borer in China (Liu et al. 2007; see above). Another native ectoparasitoid found to attack Emerald Ash Borer larvae, Atanycolus hicoriae (Braconidae) is being evaluated as a potential biocontrol agent as well. (Duan et al. 2009 and references therein)
Gandhi and Herms (2010) investigated the question of whether the large scale destruction of ashes (Fraxinus spp.) by Emerald Ash Borers in North America could result in the decline or extinction of other ash-associated arthropods.Their literature survey revealed that 43 native arthropod species in six taxonomic groups (Arachnida: Acari; Hexapoda: Coleoptera, Diptera, Hemiptera, Hymenoptera, and Lepidoptera) are known to be associated only with ash trees for either feeding or breeding purposes and are therefore at high risk. Most of these species are gall-formers, followed by folivores, subcortical phloem/xylem feeders, sap feeders, and seed predators. Another 30 arthropod species are associated with 1 to 2 host plants in addition to ash; herbivory on these hosts may increase as these arthropods shift from declining ash trees.
Life History and Behavior
In southeast Michigan, adult beetles emerge from host trees from late May through early September. Eggs are deposited singly in crevices and furrows on the outer bark of host trees. Upon eclosion, first instars immediately tunnel through the bark and begin feeding on phloem and outer xylem as they create serpentine, frass-packed galleries that impede translocation of water, nutrients, and photosynthate through the tree. Most individuals complete their life cycle in 1 year; however, a proportion of the population takes 2 years to complete development. (Rebek et al. 2008 and references therein)
Molecular Biology and Genetics
Statistics of barcoding coverage: Agrilus planipennis
Public Records: 0
Specimens with Barcodes: 7
Species With Barcodes: 1
National NatureServe Conservation Status
Rounded National Status Rank: NNR - Unranked
Relevance to Humans and Ecosystems
Kovacs et al. (2010) modeled Emerald Ash Borer spread and infestation over the period 2009 to 2019. They estimated the discounted cost of the treatment, removal, and replacement of ashes infested by Emerald Ash Borer on developed land within communities in a 25-state study area centered on Detroit. An estimated 38 million ash trees occur in this area. Their simulations predicted an expanding Emerald Ash Borer infestation that will likely encompass most of the 25 states and warrant treatment, removal, and replacement of more than 17 million ash trees with a mean discounted cost of $10.7 billion. They note that expanding the land base to include developed land outside, as well as inside, communities nearly doubles the estimates of the number of ash trees treated or removed and replaced, and hence the associated cost. The authors argue that estimates of discounted cost suggest that a substantial investment might be efficiently spent to slow the expansion of isolated Emerald Ash Borer infestations to postpone the ultimate costs of ash treatment, removal, and replacement. Although many uncertainties could change assumptions underlying the predictions of this analysis, it nevetheless provides some sense of the scale of the economic threat of the Emerald Ash Borer.
Emerald ash borer
In North America the borer is an invasive species, highly destructive to ash trees in its introduced range. The damage of this insect rivals that of Chestnut blight and Dutch Elm Disease. To put its damage in perspective the number of chestnuts killed by the Chestnut Blight was around 3.5 billion chestnut trees while there are 3.5 billion ash trees in Ohio alone. Dutch Elm Disease killed only a mere 200 million elm trees while EAB threatens 7.5 billion ash trees in the United States. The insect threatens the entire North American Fraxinus genus, while past invasive tree pests have only threatened a single species within a genus. Since its accidental introduction into the United States and Canada in the 1990s, and its subsequent detection in 2002, it has spread to 14 states and adjacent parts of Canada. It has killed at least 50 - 100 million ash trees so far and threatens to kill most of the ash trees throughout North America. The green ash and the black ash trees are preferred. White ash is also killed rapidly, but usually only after green and black ash trees are eliminated. Blue ash displays some resistance to the emerald ash borer by forming callous tissue around EAB galleries; however, they are usually killed eventually as well.
The adult beetle is dark metallic green, bullet-shaped and about 8.5 millimetres (0.33 in) long and 1.6 mm (1⁄16 in) wide. The body is narrow and elongated, and the head is flat with black eyes. The larvae are approximately 1 mm (1⁄25 in) diameter, 26 to 32 millimetres (1.0 to 1.3 in) long, and are a creamy white color. The eggs turn to a yellow brown color prior to hatching. Adults lay eggs in crevasses in the bark. Larvae burrow into the bark after hatching and consume the cambium and phloem, effectively girdling the tree and causing death within two years. The average emerging season for the emerald ash borer is early spring to late summer. Females lay around 75 eggs, but up to 300 from early May to mid-July. The borer's life cycle is estimated to be one year in southern Michigan but may be up to two years in colder regions.
The adult emerald ash borer emerges in May–July and the female lays numerous eggs in bark crevaces and between layers of bark. The eggs hatch in 7–10 days and larvae bore into the tree where they chew the inner bark and phloem creating winding galleries as they feed. This cuts off the flow of the water and nutrients in the tree, causing dieback and death.
Distribution and dates of detection
Its first confirmed North American detection was in June 2002 in Canton, Michigan. It is suspected, that it was introduced by overseas shipping containers being delivered to Yazaki North America. It has since been found in several other parts of the United States and Canada. Ohio, Minnesota, and Ontario have experienced emerald ash borer migration from Michigan. Additionally, Maryland and Virginia received shipments of contaminated trees from a Michigan nursery. The emerald ash borer was confirmed in Indiana in April 2004, in Central Kentucky in the Spring of 2009 and in Northeast Iowa in May 2010.
USDA APHIS PPQ used to attempt eradication of the insect, but its distribution is far too broad at this time and funds are lacking. Quarantine zones are still set up from which unprocessed raw hardwood material cannot be removed. The quarantine applies not only to the counties where the emerald ash borer has been detected but also high risk counties as well. The infected states have prohibited the movement of firewood from one state to another trying to eliminate the spread and fully enforce the quarantine zone. Large fines were imposed on a few companies that violated the ban, including one that was transplanting ash trees from southeast Michigan to Virginia and Maryland and is believed to be responsible for spreading the beetle to those states. The USDA has spent several hundreds of millions of dollars trying to minimize the ecological impact of EAB.
Michigan officials announced 2005-09-14 that ash borer infestation had crossed the Straits of Mackinac and was now in the Upper Peninsula for the first time. Wisconsin environmental officials consider it a grave threat and began preparations years ago for surveys in the state. Several counties in Indiana are under quarantine. However, states and cities are running out of money to combat the problem and many authorities feel that the borer will spread throughout North America. The EAB can move short distances by flying as well as surviving long distances in transit on ash tree nursery stock, Ash logs, branches, and firewood.
In June 2006, it was reported that emerald ash borers had been found at a home near Lily Lake, Illinois. Illinois officials have regulated several counties because it was found to be widespread. In July, 2006, further infestations were discovered in northern Cook County, Illinois, including Wilmette, Evanston, and Winnetka.
In June 2007, it was reported that emerald ash borers have been found in Cranberry Township, a suburb of Pittsburgh, Pennsylvania. On June 27, 2008, The Pittsburgh Post Gazette reported that the state Department of Agriculture says the emerald ash borer has been found in Mercer County. The invasive beetle was discovered in Butler and Allegheny counties last summer. Officials are surveying this year to gauge whether the insect has spread. Mercer joins Allegheny, Beaver, Butler and Lawrence counties in a quarantine prohibiting the movement of ash nursery stocks, green lumber and firewood.
In October 2007, an emerald ash borer larva was discovered in a West Virginia Department of Agriculture "detection tree" located in Fayette County. This detection tree was located in a recreational site, with camping, mountain biking, and white water rafting. It is believed that the pest arrived in firewood that was illegally transported by tourists visiting the New River Gorge area, a popular site for white water rafting (USDA-APHIS-PPQ).
As of December 2007, a federal quarantine has been imposed on the following areas in the U. S. for Emerald Ash Borer: the lower peninsula of Michigan; Mackinac County, Michigan; the entire states of Ohio, Illinois, and Indiana; Prince Georges County, Maryland; and Fayette County, West Virginia. (USDA-APHIS)
Emerald Ash Borer has also extended its distribution in Canada. As of August 2009, the following areas are regulated by the CFIA in Ontario: Essex, Lambton, Middlesex, Elgin, Huron, and Norfolk Counties, the Municipality of Chatham-Kent, the Cities of Hamilton and Toronto and the Regional Municipalities of Durham, York, Peel and Halton, the City of Sault Ste. Marie, and the City of Ottawa; in Quebec: The City of Gatineau and Municipalities of Carignan, Chambly, Richelieu, Saint-Basile-le-Grand and Saint-Mathias-sur-Richelieu.
It was confirmed by Canadian Agriculture officials to be present in Monteregie, Quebec. This region lies directly north of New England, therefore drastically increasing the likelihood of being found in New England.
On Tuesday, July 29, 2008, it was announced that the Missouri Department of Agriculture has detected the emerald ash borer in the state. On Monday, August 4, Wisconsin confirmed that the first appearance in the state was detected in the village of Newburg, Wisconsin, in Ozaukee County.
On March 11, 2009 it was confirmed in Mifflin County, Pa. This county lies in the Eastern Central part of the state. As of August 12, 2010, the Pennsylvania Department of Agriculture reports that two-thirds of the state has been infested with the EAB, most in counties west of the Pocono Mountains.
The insect was furthermore detected in Victory, Wisconsin by agricultural officials on Tuesday April 7, 2009. This town is in the western part of the state, and borders Iowa and Minnesota. It is also along the Mississippi River, which may serve as a pathway for the insect.
On May 14, 2009, spread of the emerald ash borer was confirmed by the Minnesota Department of Agriculture in St. Paul, Minnesota. This represents the most westerly location it has been found thus far in North America.
The New York State Department of Environmental Conservation announced on June 17, 2009 that the emerald ash borer was recently discovered for the first time within the borders of New York State, in the Cattaraugus County town of Randolph.
Authorities across the US are continuing to determine the exact extent of EAB by placing purple traps nationwide.
Environmental and economic impact
Evidence of the emerald ash borer sometimes takes up to a year to recognize. Some signs that the emerald ash borer has infested a tree are D–shaped holes in the bark of the trunk or branches and shoots growing from the base of the tree.
The beetle kills trees because the feeding larvae damage both the phloem (responsible for nutrient transport throughout the tree) and xylem (responsible for take-up of water and nutrients) tissues of the tree. The beetle effectively girdles the tree. One telltale sign of infestation is the presence of new 'sprouts' at the base of the tree's trunk. As long as the beetle does not eat into the bark at the very base of the tree, these sprouts can still get nutrients to grow and can continue to grow even after the main trunk is cut down. Unfortunately, once these sprouts reach one inch in diameter, they then become attractive targets for the EAB.
The insect is unusually difficult to kill. More than 7.5 billion ash trees are currently at risk. Nearly 114 million board feet (33,000 m³) of ash saw timber with a value of US$25.1 billion is grown in the eastern United States each year. Over forty million ash trees have died or are dying in the United States at this time. The full time it takes for a tree to die due to the EAB is generally two or three years.
The Emerald Ash Borer has killed nearly 30 million ash trees. Losses are estimated in the tens of millions of dollars.
The National Ash Seed Collection Initiative collects and stores ash seeds in cryogenic vaults at the National Center for Genetic Resources Preservation in Fort Collins, CO. If the population of American ash trees is destroyed, the stored seeds will be the genetic base to re-establish ash.
A pilot study is being undertaken in Michigan to determine if three different parasitic wasps can deter the emerald ash borer. These tiny stingless wasps can sense beetles underneath the bark and then lay their eggs in the larvae or egg, thus killing them. There have been doubts as to whether this biological control program will work, due to the fact that North American ash trees perish rapidly to the borer when they are planted in Asia, even where the parasitoids are present. It is not known at this time whether their release will have any unintended ecological impacts.The wasps have been released according to a Michigan newspaper. The releases began in July 2007, a few weeks later than they had hoped. (modification: USDA-APHIS-PPQ)
Effective steps to help reduce infestations and impact
- Purchase firewood at or near the campsite
- Do not bring firewood back to destination after a camping trip
- Inspect firewood. Make sure it has no bark at all or signs of infestation
- Treat already infested trees or prevent future infestation 
- Know the signs and symptoms of the borer. The quicker it is detected, the better the chance of eradication.
- If you have Ash Trees in your landscape or woodlot and desire to keep them alive, consult an Arborist for treatment options. Direct-Injections to the cambial layer (soft inner bark) have proven effective.
- ^ US Forest Service (accessed 19 January 2009)
- ^ EmeraldAshBorer.info
- ^ http://joa.isa-arbor.com/request.asp?JournalID=1&ArticleID=3011&Type=2
- ^ a b "Emerald ash borer in Indiana". Purdue University. 2007. http://www.entm.purdue.edu/EAB/index.shtml.
- ^ Jim Paul (2006-06-13). "Bug that kills ash trees found in Illinois". Associated Press. http://abcnews.go.com/Technology/wireStory?id=2073348.
- ^ "Emerald ash borer discovered in Evanston". Illinois Department of Agriculture. 2006-06-21. http://www.agr.state.il.us/newsrels/r0721061.html.
- ^ Allison M. Heinrichs (2007-06-27). "Destructive Asian insect found in Cranberry". Pittsburgh Tribune-Review. http://www.pittsburghlive.com/x/pittsburghtrib/news/cityregion/s_514585.html.
- ^ Rick Steelhammer (2007-10-21). "Emerald ash borers invade Mountain State". Charleston Gazette-Mail (Sunday Edition). http://sundaygazettemail.com/section/News/2007101928.
- ^ "Emerald Ash Borer - Agrilus planipennis". Canadian Food Inspection Agency. 2009-08-26. http://www.inspection.gc.ca/english/plaveg/pestrava/agrpla/agrplae.shtml.
- ^ Robert Mitchum and Melissa Patterson (2008-06-19). "Emerald Ash Borer hits Chicago". http://www.chicagotribune.com/features/lifestyle/green/chi-emerald-ash-borer-web-jun20,0,3794472.story.
- ^ Jake Griffin (2008-06-11). "Invasive emerald ash borer beetle found in Naperville". Chicago Daily Herald. http://www.dailyherald.com/story/?id=206123.
- ^ "L'agrile du frêne s'attaque aux arbres de la région". Canoe.ca. 2008-06-27. http://lcn.canoe.ca//infos/regional/archives/2008/06/20080627-080044.html.
- ^ "Wisconsin confirms the arrival of ash borer, putting trees at risk". Minneapolis Star-Tribune. 2008-08-04. http://www.startribune.com/nation/26263649.html.
- ^ "Minnesota finds first emerald ash borer infestation". Kare11.com. 2009-05-14. http://www.kare11.com/news/news_article.aspx?storyid=704432&catid=2.
- ^ "Emerald Ash Borer Found in New York State". NYS Department of Environmental Conservation. 2009-06-17. http://www.dec.ny.gov/press/55725.html.
- ^ http://www.ncrs.fs.fed.us/pubs/jrnl/2003/nc_2003_liu_001.pdf
- ^ Tina Lam (2007-06-28). "Debate buzzes on wasp plan". Detroit Free Press. http://www.freep.com/apps/pbcs.dll/article?AID=/20070624/NEWS05/706240667/1001/NEWS.
Emerald Ash Borer-The Morton Arboretum