SWATHES of pristine North American pine forest could be at risk from one of the world’s most destructive tree-killing pests because of climate change, experts have warned.

In the next few decades global warming may extend the range of the southern pine beetle into much of northern US and southern Canada, a new study suggests.

The impact of such an invasion on ecosystems, tourism and the timber industry is likely to be devastating, it is claimed.

Lead researcher Corey Lesk, from Columbia University in New York City, said: “We could see loss of biodiversity and iconic regional forests. There would be damage to tourism and forestry industries in already struggling rural areas.”

Infested forests could also dry out and burn, endangering property and releasing large amounts of carbon into the atmosphere.

Until recently the southern pine beetle, Dendroctonus frontalis, a native of Mexico and Central America, was confined to the south-eastern states of the US. Now it can be found across several eastern states as far north as New Jersey. The insect cannot survive if conditions are too cold, but winter lows are rising much faster than average temperatures, allowing the beetles to spread, said the scientists writing in the journal Nature Climate Change.

The researchers plotted the likely march of the beetles up the eastern Atlantic coast and through southern New England and Wisconsin.

They calculated that by 2080, climates friendly to the pest could encompass 71 per cent of red pines and 48 per cent of jack pines across 270,000 square miles of north-eastern US and southern Canada.

The red-brown beetles are no bigger than a grain of rice but cause massive damage to all species of pine tree.

Thousands of beetles burrowing under bark to feed on the underlying phloem tissue can kill a tree in two to four months. In addition the insects carry a fungus that is also deadly to the trees.

Pine beetle infestations in the south-eastern US cost the timber industry 100 million dollars (£78 million) per year from 1990 to 2004, according to the US Forest Service.

It is the coldest night of the winter that determines where the southern pine beetle can survive, said the researchers.

While average annual temperatures in many parts of the US had risen by just one degree Fahrenheit in the past 50 years, the coldest winter night had warmed by around six or seven degrees.

The scientists expected this trend to continue, with minimum winter temperatures increasing by as much as 13 degrees across north-eastern US and south-eastern Canada.

They pointed out that the temperature of pine bark is warmer than the surrounding air and a critical factor.

In New Jersey, at the end of the beetles’ current range, northernmost sightings of the insect had drifted further north by about 53 miles per decade since 2002 and were closely correlated with warmer minimum bark temperatures.