emerald ash borer

Emerald ash borer

Kingdom:	Animalia
Phylum:	Arthropoda
Class:	Insecta
Order:	Coleoptera
Family:	Buprestidae
Genus:	Agrilus
Species:	A. planipennis

Binomial name

Agrilus planipennis
Fairmaire, 1888

The emerald ash borer (Agrilus planipennis or Agrilus marcopoli) is a shiny green beetle and an invasive species known for killing ash trees in the United States.

Description

The average length for an adult emerald ash borer is ¾ in (20 mm) long and ¹⁄₆ in (4 mm) wide. The larvae are approximately 1 mm long and .6 in (15 mm) in diameter, and are a creamy white color. The color of the larvae make them very difficult to spot on a tree. The eggs turn to a yellow brown color prior to hatching.^[1] The average emerging season for the emerald ash borer is early spring to late summer. Females lay around 75 eggs from early May to mid-July. The feedings are usually finished by fall. The EAB's life cycle is estimated to be one year in southern Michigan but may be up to two years in colder regions.

The EAB find coverage in the bark crevices and in foilage during rainy weather or high temperatures.

Distribution

The natural range of the eastern ash borer is eastern Russia, northern China, Japan, and Korea. It was suspected to be accidentally imported to North America from China in the 1990s and has since destroyed more than six million ash trees in southeastern Michigan. It was discovered in June 2002 in Canton, Michigan. It has since been found in a few other parts of the United States and Canada. Ohio and Ontario have experienced emerald ash borer migration from Michigan, while Maryland and Virginia received shipments of contaminated trees from a Michigan nursery. The emerald ash borer was confirmed in Indiana in April 2004.

The U.S. Department of Agriculture is attempting to exterminate all of these beetles on the continent, and has taken the unusual measure of destroying every ash tree within a half-mile (800 m) radius of known infested trees. Southeast Michigan is a quarantine zone from which ash trees or even firewood cannot be removed. The quarantine applies only to the counties where the emerald ash borer has been detected.^[1] The infected states have prohibited the movement of firewood from one state to another helping to eliminate the spreading and fully enforce the quarantine zone. Large fines have been imposed on a few companies that violated the ban, including one that was removing ash trees from southeast Michigan and is believed to be responsible for spreading the beetle to another county. The USDA has committed at least $40 million dollars for eradication in 2004 and expects to spend over $350 million in the next twelve years.

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 considered it a grave threat and began preparations for surveys in northern counties. Currently twelve 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.^[2]

In June 2006, it was reported that emerald ash borers had been found at a home near Lily Lake, Illinois.^[3] Illinois officials plan to conduct a survey of the region, and will later hold a hearing to determine if a quarantine is necessary. In July, 2006, further infestations were discovered in Northern Cook County, Illinois, including Wilmette, Evanston, and Winnetka.^[4]

In June 2007, it was reported that emerald ash borers have been found in Cranberry Township, a suburb of Pittsburgh, Pennsylvania.^[5]

Economic impact

A green ash killed by emerald ash borers

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.^[1] Another sign of infestation is small holes in the bark where the bugs have bored their way out.

The reason the bug kills trees is because it consumes so much bark that the tree cannot get any nutrients up to the top of it. Since the inner core (heartwood) of trees is dead and the inner bark (sapwood) is the living portion of the tree, the bug effectively strangles the tree. A tell-tale sign of infestation is new shoots sprouting from the bottom of the tree. As long as the bug does not eat the bark at the very base of the tree, the small shoots at the bottom can still get nutrients. Surprisingly, even after the larger tree is cut down, some of these shoots may keep on growing.

The insect is unusually difficult to kill. More than seven 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 twenty 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 two to three years.

A pilot study is being undertaken in East Lansing, Michigan to determine if a parasitic wasp can deter the emerald ash borer. Tetrastichus planipennisi is a tiny stingless wasp that can sense beetles underneath the bark and then lay their eggs in the larvae thus killing them. 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 release was made in July 2007, a few weeks later than they had hoped to release them.^[6]