What’s going on here
A beetle species which can cause life threatening damage to spruce trees, has been shown to be attracted to a populous spruce variety across the UK and Europe. Fears that the beetle may also be attracted to the Sitka spruce variety were, until recently, unproven.
What does this mean?
The European spruce bark beetle has been found in the UK, having already caused widespread devastation of the Norway spruce variety across Europe. Estimates suggest that since 2013, the beetle species has been responsible for the deaths of more than 100m cubic metres of Norway spruce across Europe. A recent study found that the beetle is also attracted to the Sitka variety – the UK’s most productive commercial species.
The eight-toothed beetles harm trees through their reproductive cycle. Male beetles bore into the tree and attract females using pheromones. Female beetles then bore upwards or downwards through the tree, to lay their eggs. The significant damage is caused once the eggs hatch; they grow (pupate) under the bark surface, harming the channels responsible for transporting water and nutrients through the tree. This causes dieback of the upper branches and in severe cases, the whole tree. Additional harm may be caused by the beetles spreading fungal pathogens.
Why should we care?
One of the reasons that the spruce bark beetle is such a threat is that populations of the insect can rapidly expand due to the density of spruce forests. Spruce trees grown for commercial reasons can facilitate the proliferation of the beetle, as they tend to be raised in a ‘mono-crop’ arrangement. This allows the beetles to easily spread to other trees, accelerating their demise.
The mass die-off of tree populations presents a significant threat to Europe’s biodiversity. As well as being beautiful organisms, trees act as a useful store of carbon, not to mention the many other ecological benefits that they bring. Similar problems such as Dutch elm disease, have historically caused great destruction to tree populations. Ash-dieback continues to sweep across the UK. At a time when more trees are needed to fight the climate crisis, not fewer, the threat of the spruce bark beetle is a cause for grave concern.
Be Curious!
- Look out for reforestation volunteering opportunities at the Woodland Trust.
- From our archive: Existential threats driving supply chains bananas.
- Find out how to identify, and report sightings of spruce bark beetles at Forest Research.
Image: Tomasz Smal on Unsplash
