Researchers have found the majestic white pine tree teams up with a fungal henchman to slowly suck the life out in insects.

"Above ground, these trees look so harmless, but it turns out that below the surface, they are feeding on live animals," said John Klironomos. The University of Guelph botany professor discovered the pine's predatory habits with graduate student Miranda Hart.

They found that white pine trees form a partnership underground with the beige fungus Laccaria bicolor. The tree root fungus preys on insects to get nitrogen. The fungus trades the nitrogen with the host tree, which supplies carbon to the fungus.

In this way, white pine trees are acting indirectly as predators, Klironomos said. It may mean that forest nutrient cycling is more complicated than scientists previously thought.

The researchers made the discovery while studying white pines.

"When we would introduce insects to the soil – mostly springtails – they would die immediately, and we wondered why," Klironomos said.

Fungus attack

When the researchers took a closer look, they discovered the springtails (a common millimetre-long insect) were being attacked by the fungus.

The researchers think the fungus releases a toxin that paralyzes the insect. It then infects them, grows inside and eats them alive.

It was the specific combination of the white pine tree with the L. bicolor fungus that was lethal to insects and most beneficial for the tree.

Science has long recognized the importance of the partnership between trees and stringy fungi that reach where roots can't go. But it had been commonly believed that trees and their fungi got nutrients like nitrogen from dead organic matter in the soil.

The study appears in the April 5 edition of Nature.