Agrilus biguttatus (two spotted oak buprestid, TSOB) is an iridescent blue or bronze-green beetle, with white spots on its wing-cases. TSOB is native to the UK, and was formerly thought of as a rare, vulnerable species. Today, it appears to be increasingly common, and is causing concern because of its links with Acute oak decline. Although the beetles are difficult to observe in their natural habitat, it is possible to identify the D-shaped exit holes that are formed as the beetles emerge from the bark.
Forest Research is investigating TSOB’s lifecycle and distribution, and the role that the beetle plays in acute oak decline. We aim to determine:
- The role of temperature in the development of the beetle, and the duration of its lifecycle
- The potential impacts of climate change on the beetle’s life cycle and distribution
- Whether TSOB may be involved in the transmission of pathogenic bacteria between or within trees
- When oak trees become suitable for larval development
Distribution and ecological status in the UK
Although formerly considered rare, TSOB seems to be increasingly common in the UK. The beetle shares a similar distribution to acute oak decline, and this is one reason it is thought to be implicated in the decline.
Lifecycle and damage to trees
Damage to trees occurs when the larvae feed on the vascular tissues in the inner bark, creating galleries. TSOB’s D-shaped exit holes and larval galleries are frequently found on trees showing symptoms of acute oak decline