As in continental Europe, forests in Britain are also threatened by the eight-toothed bark beetle – a small but voracious beetle that reproduces extremely quickly under favorable conditions, writes the BBC.
The eight-toothed bark beetle has destroyed millions of spruce trees in Europe, and the British government hoped to stop its spread by checking the wood imported into the country. It turned out that the bark beetle does not need ships – the wind carries the beetles across the English Channel. Now government scientists are fighting using unusual methods, including specially trained dogs and drones.
The eight-toothed spruce bark beetle has been destroying conifers in Europe for decades. The beetle lays its eggs under the bark, and the new generation feeds on the wood. If a tree has a few thousand beetles, it can still recover, fighting off the beetles with increased resin secretion. But weakened trees have lower defenses and bark beetles multiply rapidly.
Max Blake, head of the tree health department at the British government’s Forest Research Service, explained that bark beetle populations can grow so large that a tree can no longer protect itself, with millions, if not billions, of beetles.
Since the eight-barked bark beetle appeared in Norway, it has destroyed 100 million cubic meters of spruce.
Sitka spruce is the main source of timber in Britain, and Blake and his colleagues have been watching the beetle’s spread across continental Europe with concern. Andrea Deol, a spokeswoman for the Forest Research Service, said that the country has 725,000 hectares of spruce, and if the beetle is allowed to multiply, most of that spruce is at risk.
The government’s plant health plan lists more than 1,400 pests and diseases, but the eight-toothed bark beetle is currently considered the most dangerous. True, the number of pests and diseases is constantly increasing. Nick Phillips, a representative of the charity The Woodland Trust, pointed out that the main reason for this is international trade – timber and tree seedlings are imported, which can sometimes bring “subtenants”. The Forest Research Service, together with the Border Guard, has been testing trees and wood products for years to avoid the beetle’s introduction, but this did not protect against an unpleasant surprise in a forest in Kent. Deol explained that the forest found a population of beetles that had been living there for years. Later, researchers caught such a number of beetles in traps that they indicated that they had arrived on the island by other means. Current research suggests that the bark beetle had been blown from the continent by wind.
It was clear that action was needed quickly, and techniques were developed that could also be used in a military operation. Drones were flown to survey hundreds of hectares of forest for signs that the trees might be infested with beetles. When the bark beetle population in a tree is too high, it can no longer transport nutrients and water to the top branches, and they begin to wither. The next step is for entomologists to examine the trees from the ground. Deol said it is like looking for a needle in a haystack, sometimes looking for a single beetle to catch the first ones and prevent them from multiplying. In one year, her team inspected 4,500 hectares of spruce forest.
The work is physically demanding and time-consuming, and ways are being sought to make it easier.
When the first bark beetles find suitable trees, they release pheromones that attract other beetles. Their strong sense of smell means dogs can be used to sniff out the beetles. Early trials have been successful, and the dogs are particularly useful for searching through large piles of timber that are difficult to visually inspect.
Cameras are also being used on beetle traps, allowing the traps to be checked daily to detect the beetles more quickly.
The combination of measures has made the UK the first country to eradicate the eight-toothed bark beetle from a controlled area. Deol said that their work is having a positive impact and it is important that we continue our efforts; but if they get careless, there is a risk that the bark beetle will return every year. And the risk is growing. Europe is seeing an increase in bark beetle populations as trees are weakened in an attempt to cope with climate change. Winters are getting rainier and milder, meaning there is less frost and the trees are more humid. Combined with severe and prolonged dry spells in the summer, this weakens trees and increases the chance of trees breaking off in storms. This also gives the beetle every opportunity to multiply. As the beetles spread across continental Europe,
the chances of them reaching Britain also increase.
A team from the Forest Service is working to predict where the beetles might appear in Britain. Together with scientists from the University of Cambridge, they have applied an atmospheric dispersion model, which is usually used to determine where radioactive particles will travel after a nuclear disaster. Now they are trying to predict the direction of movement of the eight-toothed bark beetle.
Phillips supports the government’s work, but is concerned about the loss of old-growth forests. Commercial spruce stands are usually planted next to old, biologically valuable forests, and every time bark beetles are found in a spruce stand, both the bark beetles and the surrounding forests have to be felled. Phillips said he wants the government to preserve as many old trees as possible that are not affected by the bark beetle.
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