Source: European Commission (RTD)

Europe’s forests face a growing threat from pests due to global trade and climate change, but scientists are developing techniques that can give an early warning of infestations to help combat damaging insects and diseases.

Pests are responsible for damaging 35 million hectares of forest around the world every year. In the Mediterranean region alone an area the size of Slovakia – five million hectares – is affected by pests annually, according to the UN Food and Agriculture Organization (FAO).

And the threat posed by insects and pathogens appears to be growing. Climate change is allowing some native pests to breed more frequently, while international trade is spreading exotic insects and pathogens more widely.

Only a tiny proportion of exotic pests that arrive in Europe end up damaging trees. ‘But these are very harmful, and there are more and more (of them),’ said Dr Hervé Jactel, director of research for forest entomology and biodiversity at the French National Research Institute for Agriculture, Food and Environment. 

On average, six new species of tree pests are being introduced to Europe every year, up from two a year in the 1950s, says Dr Jactel. They arrive in potted plants and wooden products or packaging.

Many of the emerging threats to Europe’s forests originate in Asia.

The emerald ash borer, for example, spread from Asia to the United States where it killed more than 150 million trees and may have cost more than $10 billion in the last decade. It is now knocking at Europe’s door.

‘We know it will kill all ash trees, or most of them,’ said Dr Jactel, who is the coordinator of the HOMED project which is developing new ways to detect such exotic pests early.

The polyphagous shot-hole borer is another major threat. It can attack virtually all deciduous tree species in Europe, says Dr Jactel. ‘It’s a very, very dangerous tiny beetle,’ he said. ‘This is probably the next big issue for Europe.’

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