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Agrilus planipennis

EPPO code 

AGRLPC

Common names

English name: Emerald Ash Borer
Nordic names: Asiatisk askepragtbille (DK)  

Major host plants

Hosts of A. planipennis are probably all species of Fraxinus, including F. excelsior. Asian species of Juglans and Ulmusare hosts too, but susceptibility of the European species is unknown.  

Symptoms

The symptoms can include: 

  • Serpentine galleries and D-shaped exit holes (3-4 mm in diameter)
  • Frass-filled larval galleries in the cambium
  • Bark splitting: vertical fissures (5-10 cm) on bark due to callous tissue formation, galleries exposed under bark split
  • Canopy dieback: begins in top one-third of canopy, progresses until tree is bare
  • Epicormic shots: sprouts grow from roots and trunk, leaves often larger than normal
  • Increased woodpecker activity/damage: several woodpecker species feed on A. planipennis larvae/pupae
Agrilus planipennis. Courtesy EPPO: Daniel A. Herms, The Ohio State University (US)
Agrilus planipennis. Courtesy EPPO: Daniel A. Herms, The Ohio State University (US)

See more pictures on EPPO’s website. 

Distribution

Native to Asia, it has been found in China, Korea, Japan, Mongolia, Taiwan and eastern Russia. It likely arrived in the United States hidden in wood packing materials commonly used to ship consumer goods, auto parts and other products. In 2007 it was found in Moscow, Russia, where it has spread wide around.

A map can be downloaded from Eppo's website. See instructions here.

Biology

The Emerald Ash Borer generally has a one-year life cycle but it could take two years to complete its life cycle in colder climates. Adult beetles are active during the day, from mid-June to mid-August. Females can mate multiple times and lay 60 to 90 eggs during their lifetime. Eggs are deposited individually in bark crevices on a trunk or branches and hatch in seven to 10 days. After hatching, larvae chew through the bark and feed on phloem and outer sapwood for several weeks. Feeding is complete in autumn and pre-pupal larvae overwinter in shallow chambers in the outer sapwood or in bark. Pupation begins in late April or May. Adults emerge head-first through a D-shaped exit hole that is 3 to 4 mm in diameter. 

Major pathway(s)

A. planipennis can fly up to several kilometers to seek new host material, but when hosts are available they fly less than 500 m. 
Long distance dispersal is generally the result of people moving infested material. A. planipennis can be spread to new areas on firewood, nursery stock, trees, logs, and any lumber or wood with and without bark attached, including bark chips.

Detection and Inspection

It can be difficult to detect A. planipennis infestations. The presence of woodpeckers and the holes they dig to get to the pests may be one of the first signs of infestation. When a tree has been infested for one year, the D-shaped holes left when adults emerge will be present on the branches and trunk. Another sign of infestation is the growth of epicormic shoots. Moreover, as no European species of Agrilus is known from ash, the occurrence of galleries typical of this genus in ash trees should automatically be suspected.  

Pest status and importance

A. planipennis primarily damages and kills ash trees. Trees usually die within three years following initial attack, though heavier infestations can kill them within 1 – 2 years. Attacks by A. planipennis can cause direct loss of the attractive and high-quality wood of Fraxinus spp., which is used for a variety of products. 
In view of its area of origin and the area where it has been introduced, it seems highly probable that A. planipennis would be able to establish in most of Europe, where Fraxinus spp. are common, causing an impact on Fraxinus spp. in cities and amenity plantations and probably also in woodlands.

Source of information

See further information here:

Author: Christiane Scheel
Editor: Elise T. Yamamoto Buch  

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