Emerald ash borer

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For the infestation of this insect in North America, including control methods, see Emerald ash borer infestation.
Emerald ash borer
Agrilus planipennis 001.jpg
Scientific classification e
Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Coleoptera
Family: Buprestidae
Tribe: Agrilini
Genus: Agrilus
Species: A. planipennis
Binomial name
Agrilus planipennis
Fairmaire, 1888
Synonyms[1]
  • Agrilus feretrius Obenberger
  • Agrilus marcopoli Obenberger

The emerald ash borer (Agrilus planipennis) is a green beetle native to Asia and Eastern Russia.[2] Outside its native region, the emerald ash borer (also referred to as EAB) is an invasive species, and emerald ash borer infestation is highly destructive to ash trees in its introduced range.[3] The emerald ash borer was first discovered in America in June 2002 in Michigan. It is believed to have been brought to America unintentionally in ash wood which was used to stabilize crates during shipping.

Life cycle[edit]

Underside of Agrilus planipennis
Agrilus planipennis mating

The emerald ash borer life cycle can occur over one or two years depending on the time of year of oviposition, the health of the tree, and temperature.[4]

Adult beetles are typically bright metallic green and about 8.5 millimeters (0.33 in) long and 1.6 millimeters (0.063 in) wide. Underneath the elytra, the upper side of the abdomen is coppery-red, which is a distinctive feature of the species.[4] After 400-500 accumulated growing degree days (GDD) at base 10 °C (50 °F), adults begin to emerge from trees, and peak emergence occurs around 1000 GDD. After emergence, adults feed for one week on ash leaves in the canopy before mating, but cause little defoliation in the process.[5] A typical female can live around six weeks and lay approximately 40–70 eggs, but females that live longer can lay up to 200 eggs.[5]

Eggs are deposited between bark crevices, flakes, or cracks and hatch about two weeks later. Eggs are approximately 0.6 to 1.0 millimeter (0.024 to 0.039 in) in diameter, and are initially white, but later turn reddish-brown if fertile.[4][5] After hatching, larvae chew through the bark to the phloem and cambium where they feed and develop. Emerald ash borer has four larval instars. By feeding, larvae create long serpentine galleries. Fully mature fourth-instar larvae are 26 to 32 millimeters (1.0 to 1.3 in) long.[4] In fall, mature fourth-instars excavate chambers in the sapwood or outer bark where they fold into a J-shape. These J-shaped larvae shorten into prepupae and develop into pupae and adults the following spring. To exit the tree, adults chew holes from their chamber through the bark, which leaves a characteristic D-shaped exit hole. Immature larvae can overwinter in their larval gallery, but can require an additional summer of feeding before emerging as adults the following spring.[4]

Effect on trees[edit]

The most significant damage to a tree by the emerald ash borer takes place when the insect is in its larval stage. The larvae feed on the conductive tissue of the tree. This tissue is what transfers the nutrients and water from the roots to the leaves, and when this is disturbed, the tree begins to die. At the onset of winter, the larvae relocate to the bark of the tree, effectively cutting off the tissue more. This ultimately results in the death of tree.[6] This can take place over a number of years, and the first noticeable sign is usually some die back in the crown of the tree. The tree will usually be dead by the following year or soon after. In areas where the insect is invasive and has no natural predators, it can and usually does have a devastating effect on the local ash tree population.

Treatment[edit]

Prevention of EAB is possible by the use of a systemic insecticide into the base of the tree.[7] This treatment can prevent damage to the tree for up to two years. Note that application must be reapplied every two years. Soil injections are another option for the prevention of EAB. These insecticides are injected directly into the soil surrounding the base of the tree, and are then transported through the rest of the tree via the roots. In order for these treatments to have the greatest effect soil must be moist when applied. Water logged or dry soils will result in less of the insecticide to be absorbed into the tree. There are two insecticide spray treatments that can be used as well. The first is a spray which is applied to the trunk and absorbed through the bark. This treatment is less invasive to the tree and soil, however if the tree has thick bark absorption is slow and limited. The second spray treatment is a protective cover spray, which is applied to the branches and trunk of the tree. This treatment kills adult beetle and newly hatched larva; however it will not kill eggs.

Identification[edit]

The French priest and naturalist Armand David collected a specimen of the emerald ash borer during one of the trips he took through imperial China in the 1860s and 1870s. He found the beetle in Beijing and sent it back to France, where a brief description was published by the entomologist Leon Fairmaire published in the Revue d'Entomologie in 1888.[8]

Invasive nature[edit]

For an article detailing the infestation of this insect in North America, including control methods, see Emerald ash borer infestation.

North America[edit]

The emerald ash borer likely entered North America in Canton Township, Michigan, sometime in the early 1990s, according to a reconstruction of its spread by researchers from Michigan State University and the U.S. Forest Service.[9] It is estimated that there are 8 billion ash trees in the United States. Since the arrival of the emerald ash borer, approximately 150-200 million ash trees have already died and this number is expected to rise.[10] The EAB travels by the movement of firewood and nursery stock. The beetle, once in its adult life stage, can also fly up to a half mile under its own power. The emerald ash borer has spread to 22 states within the United States as well as Canada, since its discovery in North America in 2002. Certain areas in North America have been federally quarantined by the United States and Canadian national governments to prevent the spread of the EAB into other areas forested by ash trees. The largest area consists of the region stretching from the midwestern area of the United States to the eastern coast.

Disruption of species[edit]

Polar vortex of 2014[edit]

In early 2014, the midwestern and northern parts of the United States were hit with below average freezing temperatures brought about by a weak polar vortex. These areas in the United States experienced temperatures ranging from −27 to −18 °C (−16 to 0 °F)[citation needed]. The EAB is said to be able to persist at temperatures as low as −27 °C (−16 °F), making scientists cautious as to predict their partial attrition by this weather event[citation needed]. Emerald ash borers retain a certain coping mechanism in cases of extreme cold; they purge their gut contents which have the propensity to freeze and fold their bodies in half to reduce their size.[6] This allows the EAB to sustain periods of extreme cold, such as a those brought about by a weak polar vortex.[11] Once the polar vortex had passed, researchers with the U.S. Forest Service reported EAB attrition rates as high as 80% in some areas of Minnesota.[12] The EAB is expected to come back, as not all areas infested with EAB experienced cold enough temperatures to threaten the insect.

See also[edit]

References[edit]

  1. ^ "Data Sheets on Quarantine Pests: Agrilus planipennis". OEPP/EPPO Bulletin (European and Mediterranean Plant Protection Organization) 35 (3): 436–438. 2005. doi:10.1111/j.1365-2338.2005.00844.x. Retrieved August 28, 2013. 
  2. ^ "Agrilus planipennis (insect)". Global Invasive Species Database. ISSG-IUCN. August 14, 2006. Retrieved August 28, 2013. 
  3. ^ "Emerald Ash Borer". Don't Move Firewood. Retrieved August 28, 2013. 
  4. ^ a b c d e Gould, Juli S.; Bauer, Leah S.; Lelito, Jonathan; Duan, Jian (May 2013). Emerald Ash Borer Biological Control Release and Recovery Guidelines (PDF). Riverdale, MD: USDA-APHIS-ARS-FS. Retrieved August 28, 2013. 
  5. ^ a b c Herms, Daniel A.; McCullough, Deborah G. (October 2013). "Emerald Ash Borer Invasion of North America: History, Biology, Ecology, Impacts, and Management". Annual Review of Entomology 59: 13–30. doi:10.1146/annurev-ento-011613-162051. Retrieved May 21, 2014. 
  6. ^ a b Schaper, David. "The Upside Of The Bitter Cold: It Kills Bugs That Kill Trees". NPR. Retrieved March 2, 2014. 
  7. ^ Herms, Daniel A.; McCullough, Deborah G.; Smitley, David R.; Sadof, Clifford S.; Cranshaw, Whitney. "Insecticide Options for Protecting Ash Trees from Emerald Ash Borer" (PDF). Retrieved May 14, 2014. 
  8. ^ Miller, Matthew. "Battle of the Ash Borer: Decades after Beetles Arrived in Michigan, Researchers Looking to Slow Devastation". Lansing State Journal. Retrieved August 20, 2014. 
  9. ^ Siegert, Nathan W.; McCullough, Deborah G.; Liebhold, Andrew M.; Telewski, Frank W. (July 2014). "Dendrochronological Reconstruction of the Epicentre and Early Spread of Emerald Ash Borer in North America". Diversity and Distributions 20 (7): 847–858. doi:10.1111/ddi.12212/abstract. 
  10. ^ Poland, Therese; McCullough, Deborah (April–May 2006). "Emerald Ash Borer: Invasion of the Urban Forest and the Threat to North America’s Ash Resource". Journal of Forestry. 
  11. ^ Matus, Morgan. "Polar Vortex’s Possible Only Benefit is That It Helped Kill Off Some Invasive Insects". Inhabitat. Retrieved March 2, 2014. 
  12. ^ Fears, Darryl (March 3, 2014). "Winter’s Freeze Stopped Ash Borers and Stink Bugs Cold, but They’re Primed for a Comeback". The Washington Post. Retrieved March 3, 2014. 

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