Page last updated at 14:21 GMT, Monday, 23 June 2008 15:21 UK

Beetle expert on 'party animal'

Mountain pine beetle. Photo: Leslie Manning Natural Resources Canada
Magnified - the mountain pine beetle can kill trees

A scientist investigating the devastating impact of a beetle on pine trees in Canada has likened their behaviour to guests at a party.

Dr Javier Gamarra, of Aberystwyth University has produced a mathematical model to predict mountain pine beetles' infestation in milder weather.

Pine forests are worth millions to the economy of British Columbia.

Dr Gamarra says warmer winters are encouraging larvae to survive and bigger "parties" of beetles to form.

The female beetles attack lodgepole pines by boring through the bark to deposit eggs.

The larvae then feed on the tree, which cause it to die within weeks.

As well as the impact on forestry and the economy, experts in Canada are also worried rotting trees could create carbon in years to come.

Dr Gamarra illustrates his model by comparing the way the beetle spreads out in the forest to the behaviour of guests arriving at a party.

Dr Javier Gamarra, of Aberystwyth University
Dr Javier Gamarra says the warmer the winter, the bigger the beetle 'party'

"By observing people as they arrive at the party, you will find that the early arrivals will group together," he said.

"As more and more arrive they form groups, the more guests the greater the size difference between the largest and smallest groups.

"If you happen to be a shy, cold and lonely soul your chances of ending up in a corner with your drink as your only companion increase as the party grows.

"However being the warm, popular guy, your ego will be rewarded the more people come in."

He says a cold winter means a small party - in beetle terms - with the number of larvae reduced.

But milder weather increases survival rates and much bigger beetle rates and a greater geographical spread.

In the 10 years to 2007, forestry the size of England has been affected by infestation
It is estimated that by 2013, the beetle will have killed 80% of the pine in the centre and south of British Columbia
Consecutive mild winters - minimum temperatures above -40 C - mean more larvae live, while fire controls have allowed mature forests to grow and triple the beetle's food supply

The pine beetle attacks old or weakened trees naturally, however with large populations, they start attacking healthy trees.
The beetles introduce a blue-stain fungus into the sapwood that prevents the tree from combating the beetles with resin. It blocks water and nutrients
In the short term, there is an expanded supply of wood that needs to be sold in affected areas but there are worries for the long term economic impact
Source: Natural Resources Canada and Canadian Forest Service

"Warmer areas such as deeper valleys will attract more beetles and suffer more damage," he said.

Dr Gamarra is now trying to expand his "party hypothesis" to other pests.

"Preliminary analyses point to other pests exhibiting the same pattern of behaviour, like the desert locust in the Sahara.

"The bad news is that climate change will produce increasingly mild winters, reducing larval mortality and raising the risk of damage to many forests and crops."

As well as the impact on forestry and the economy, experts in Canada are also worried rotting trees could produce a carbon effect in years to come.

The findings are published today in the British Ecological Society's Journal of Animal Ecology.

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