Taxonomic name: Agrilus planipennis Fairmaire
Synonyms:
Common names: emerald ash borer
Organism type: insect Agrilus planipennis, commonly known as the emerald ash borer (EAB), is an insect from a family of beetles generally referred to as metallic wood-boring beetles. A. planipennis is native to Asia and eastern Russia, and is only a minor pest in its native range. The beetle was discovered in Michigan and Ontario, Canada in 2002. Despite quarantine regulations and eradication attempts including burning of large numbers of infested trees, A. planipennis continues to spread. It is now present in Illinois, Indiana, Maryland, Michigan, Missouri, Ohio, Pennsylvania, Virginia, Wisconsin, West Virginia and parts of Canada. It colonizes and kills ash trees in the genus Fraxinus killing healthy ash trees in urban and forested areas. It now threatens more than eight billion ash trees in the continental United States. This has had significant ecological and economic effects. Similar damage is now occurring in the region of Moscow, Russia which causes serious concern for Europe if it continues to spread. Similar Species
Agrilus anxius, Agrilus bilineatus, Agrilus subcinctus
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Occurs in:
agricultural areas, natural forests, planted forests, urban areas Habitat description
Nomura (2002) reports that, "A variety of hardwood trees serve as hosts to A. planipennis. Fraxinus americana (White ash), F. chinensis (Chinese ash), F. japonica (Japanese ash), F. lanuginosa (Chinese flowering ash), F. mandshurica (Manchurian ash), F. nigra (Black ash), F. pennsylvanica (red or green ash), Juglans mandshurica (Manchurian walnut), Pterocarya rhoifolia (Japanese wingnut), Ulmus davidiana (Japanese elm), U. propinqua (Chinese cork bark elm)." General impacts
Nomura (2002) states that, "During the early stage of an infestation, when A. planipennis population is low, the initial damage is low. However, after 2 to 3 years of continuous infestation, the population builds up, and eventually the tree's nutrient and water transport system is disrupted, culminating in wilting and eventual tree mortality. A. planipennis will kill apparently healthy trees during high beetle population levels which are probably triggered by a few years of hot and dry climatic conditions. A. planipennis can cause severe damage to ash stands over 8 years of age that are not crown-closed, with good sun light penetration, and that are comprised of trees with bark fractures. After 1 to 2 years of infestation, the bark often falls off in pieces from damaged trees thereby exposing the tunnel-ridden sapwood."
Nomura (2002) reports that damage consists of, "D-shaped exit holes along the lower bole surface are clear signs of buprestid beetle activity, however, careful examination is required as these are very cryptic. Frass filled, zigzagging tunnels about 6mm wide at the sapwood/bast interface are signs of A. planipennis feeding. Callus tissue produced by the tree in response to larval feeding may cause vertical splits 5 -10cm in length to occur in the bark above a gallery." MDNR (2004) states that, "Infested trees exhibit top-down dieback, with 1/3 to 1/2 of branches dying the first year and the remaining canopy dying the following year. This is often followed by a large number of shoots arising below the dead portions of the trunk. Borers make a small (1/16 inch diameter) "D"-shaped hole when entering the tree and several distinct "S"-shaped tunnels may be present under the bark. Trees may also exhibit 5-10cm vertical splits in the bark in response to larval feeding.
A. planipennis attacks ash trees in the genus Fraxinus. All North American ash species that occur within the current EAB range have been killed by EAB, including white ash (F. Americana), green ash (F. pennsylvanica), black ash (F. nigra), blue ash (F. quadrangulara) and pumpkin ash (F. profunda) (Lindell et al. 2008). Attacks on non-ash species have not been observed in North America to date, but there is concern that other species could be vulnerable. If A. planipennis host range extends beyond Fraxinus spp., the impacts of this invasive pest in North American forests would increase dramatically. Anulewicz et al. (2008) assessed A. planipennis landing rates, oviposition and larval development in a number of North American tree species. They found that “although A. planipennis adults will occasionally land on and oviposit on logs and trees of non-ash species, A. planipennis larvae did not successfully develop on anything other than Fraxinus species” (Anulewicz et al. 2008).
The three main ash species in Europe are F. excelsior, the most widespread species, and F. ornus and F. angustifolia. Nothing is known of the susceptibility of these to A. planipennis, so evaluating the resistance of these European species should be a research priority. F. excelsior is a common forest and urban tree used for timber, flooring, tool making and for its medicinal properties (FRAXIGEN 2005 in Baranchikov et al. 2008). All three species are important components of forest ecosystems in Europe and “their disappearance would have serious consequences for native biodiversity and ecosystem services” (Baranchikov et al. 2008). Geographical range
Native range: The emerald ash borer’s native range includes China, Mongolia, North Korea, South Korea, Japan, Taiwan, and the Russian Far East (APHIS-USDA 2008).
Known introduced range: In North America, EAB infestations are known to exist in Illinois, Indiana, Maryland, Michigan, Missouri, Ohio, Pennsylvania, Virginia, Wisconsin and West Virginia, as well as the Canadian provinces of Ontario and Quebec (APHIS-USDA 2008). It has also recently been discovered in the Moscow region of Russia (Baranchikov et al 2008). Introduction pathways to new locations
Forestry: Although Agrilus planipennis is a good flier, human activities are the primary cause of long distance spread. This includes moving infested trees, logs, and firewood (MDNR, 2004).
Nursery trade: Movement of infected nursery stock (Herms et al. 2003).
Solid wood packing material: Nomura (2002) states that, "Any life stage (eggs, larvae, pupae and adults) can be moved with raw wood with bark for processing, dunnage and crating for heavy goods, nursery stock, lumber and wood with bark attached and firewood, etc."
Local dispersal methods
Natural dispersal (local): Nomura (2002) states that, "Flight dispersal is generally reported to be local, usually not more than 8 to 12 m in distance and not more than 1 to 2 m in height. However, according to Nomura, this particular species differs from other members of the genus and is capable of dispersal flight up to a few kilometres to seek new host material." Management information
Preventative measures: In 2002, United Nation FAO's (Food and Agriculture Organisation) Interim Commission on Phytosanitary Measures imposed a global standard for treating wood packaging International Standard for Phytosanitary Measures No. 15 to stop the spread of invasives.Chemical: Smitley and McCullough (2004) suggest various chemical options for treatement of infected trees: (1) Using soil injections or soil drenching with imidacloprid. The authors state that, "This nicotine-like insecticide can be applied to soil as a drench or applied by professionals using a high-pressure soil injection system." This process works by killing larvae tunneling under the bark and does not kill adults. The authors suggest two technique of trunk injections of imidacloprid; one option is to use a hand-held device called a Wedgle to inject imidacloprid (sold as Pointer) into the trunk, the other is to use Imidacloprid formulated into Mauget capsules (sold as Imicide) to be injected around the base of the trunk by professional applicators. (2) Trunk injections of bidrin (Injecticide-B) (an organophosphate insecticide) that is formulated into Mauget capsules to be injected around the base of the trunk by professional applicators.(3) Trunk and foliage spray with cyfluthrin (Tempo or Bayer Advanced Garden Multi-Insect Killer) is another option suggested by the authors. They instruct the user to spray the trunk and foliage when beetles first emerge and again 4 weeks later. (4) A trunk-only spray with bifenthrin (Onyx) to be sprayed when beetles first emerge, in early to mid-June, and again 4 weeks later. The authors advise to apply bifenthrin as directed on the Onyx label for borers. Insecticides are only effective against borers as a preventative, as they have no impact on borers already in the tree. The systemic insecticide imidacloprid requires 6-8 weeks for uptake and distribution, and should therefore be applied in early to mid spring to impact newly hatched larvae in July Herms et al. 2003). Biological: Trunk-only spray with Beauveria bassiana fungal spores (Botanigard) is a biocontrol treatment that can be performed. The authors state that, "At this time, this is the only microbial control product being promoted as an alternative to insecticides for protecting ash trees. Research tests have shown that spraying trunks with Beauveria causes infection and death of emerging emerald ash borer beetles (up to 50 percent). At this time, however, we do not have test data to show how well this product protects trees from emerald ash borer attack." Reproduction
Nomura (2002) states that, "Mating occurs 7 to 10 days after emergence or flight dispersal, most often between 9:00 and 15:00h. Females can mate several times and oviposition begins 7 to 9 days after mating, when eggs are mature. Eggs are laid singly on the sunny side of the tree trunk in bark crevasses or thick branches. Each female may lay 68 to 90 eggs (average 76.6 eggs). Adult females live about 21.6 days whereas males live only about 13 days. Eggs hatch in 7 to 9 days. After hatching, first-instar larvae initially bore through the bark to feed on the phloem and eventually feed on the outer surface of the sapwood as they grow. Growing larvae as they feed form tunnels that are flat and wide, and zig-zag (S-shaped) throughout the bast and outer sapwood. Tunnels may be as long as 9 to16cm and they are filled with brownish sawdust and frass. In Michigan, U.S.A. tunnels are reported to be between 20 and 30cm long. Most of the tunnels tend to occur in the basal portion of the tree trunk up to a height of 1.8 m. Larvae then overwinter one or two seasons depending on environmental conditions. Pupation takes place in the spring (late April or early May) at the end of a tunnel near the surface of the sapwood just beneath the phloem (5 to 10mm) or even in the corky tissue in thick-barked trees. Newly eclosed adults stay in the pupal chamber about 8 to 15 days after emergence to properly harden and then bore a D-shaped exit hole (3.5 by 4.1mm in size) from the tree trunk." Lifecycle stages
Scarr et al. (2002) reports that, "A. planipennis appears to have a one-year life cycle except in northern China where it has been documented as having a two year life cycle. Eggs are laid singly in bark crevices in late spring through early summer, and hatch in 7 to 9 days. Female can lays an average of about 77 eggs. The larvae tunnel in the cambial layer, feeding on the phloem and outer sapwood, scoring deeper into the sapwood as the larvae increase in size. Larva feed aggressively until cooler fall temperatures arrive in autumn, and then over winter in the tree. All larval stages can over winter. Pupation occurs next year in late spring. The pupal chamber is constructed by tunneling into the sapwood at a shallow angle. The head of the pupa faces outward toward the bark. Newly formed adults remain in their pupal chambers for 8-15 days, and then bore through the bark to the outside. Adults emerge in early summer. Much of this data is based off native Chinese specimens. Similar observations have been made in North America, but numerous adults were observed in southeastern Michigan and Windsor in late June, and even mid and late July, suggesting a longer emergence period. Adults prefer the sunnier, warmer sides of the trees and are often found resting or flying in the sunlit portions of the crown. They are more active on clear days with little wind. Adult females live approximately 22 days; whereas males live an average of 13 days. Mating occurs during the first 7-10 days after emergence, with females mating multiple times. The beetles sometimes feign death and drop to the ground when disturbed. They are more sedentary when the weather is cloudy, rainy, windy, or very hot, when they sit immobile on foliage or in bark cracks." Reviewed by: Dr. Deborah G. McCullough Associate Professor Dept. of Entomology and Dept. of Forestry Michigan State University USA
Compiled by: National Biological Information Infrastructure (NBII) & IUCN/SSC Invasive Species Specialist Group (ISSG)
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Last Modified: Monday, 14 August 2006
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