Washington, Apr 2 (IANS): Honey bees "self-medicate" when their colony is infected with a harmful fungus, with the help of antifungal plant resins to ward off the invader, a study reveals.

"The colony is willing to expend the energy and effort of its worker bees to collect these resins," said Michael Simone-Finstrom, postdoctoral researcher in entomology at North Carolina State University, who co-authored the study with Marla Spivak of the University of Minnesota.

"So, clearly this behaviour has evolved because the benefit to the colony exceeds the cost," added Simone-Finstrom, the journal Public Library of Science ONE reported.

When faced with pathogenic fungi, wild bees line their hives with more propolis - the waxy, yellow substance, a mix of plant resins and wax with antifungal and antibacterial properties, said a university statement.

Domesticated honey bees also use propolis to fill in cracks in their hives. However, researchers found that, when faced with a fungal threat, bees bring in significantly more propolis - 45 percent more, on an average.

The bees also physically removed infected larvae that had been parasitized by the fungus and were being used to create fungal spores.

Researchers know propolis is an effective antifungal agent because they lined some hives with a propolis extract and found that the extract significantly reduced the rate of infection.