Chennai, April 4, 2012: Propolis or bee glue is a resinous substance collected by cavity nesting bees to close the cracks and crevices of their nest as a means of protection from attacks of pests and predators. The Indian honey bee does not use propolis as much as the European bee does. A recent study shows that bees use propolis also to control pathogens.
Writing about the use of propolis, the authors, Simone-Finstrom of North Carolina State University, Raleigh and Spivak of University of Minnesota, St. Paul, USA say in the Abstract of their paper* published in the latest issue of the journal PLoS ONE: "The constant pressure posed by parasites has caused species throughout the animal kingdom to evolve suites of mechanisms to resist infection. Individual barriers and physiological defenses are considered the main barriers against parasites in invertebrate species. However, behavioral traits and other non-immunological defenses can also effectively reduce parasite transmission and infection intensity. In social insects, behaviors that reduce colony-level parasite loads are termed "social immunity." One example of a behavioral defense is resin collection. Honey bees forage for plant-produced resins and incorporate them into their nest architecture. This use of rsins can reduce chronic elevation of an individual bee's immune response."
Following is the news release dated March 30, 2012 by the North Carolina State University News Room.
*Reference cited: Simone-Finstrom, M.D. and Spivak, M. 2012. Increased resin collection after parasite challenge: a case of self-medication in honey bees? PLoS ONE 7(3): e34601. doi: 10.1371/journal.pone.0034601
NORTH CAROLINA STATE UNIVERSITY NEWSROOM
Bees 'Self-Medicate' When Infected With Some Pathogens
Release date: 03.30.2012
Research from North Carolina State University shows that honey bees "self-medicate" when their colony is infected with a harmful fungus, bringing in increased amounts of antifungal plant resins to ward off the pathogen.
"The colony is willing to expend the energy and effort of its worker bees to collect these resins," says Dr. Michael Simone-Finstrom, a postdoctoral research scholar in NC State's Department of Entomology and lead author of a paper describing the research. "So, clearly this behavior has evolved because the benefit to the colony exceeds the cost."
Wild honey bees normally line their hives with propolis, a mixture of plant resins and wax that has antifungal and antibacterial properties. Domesticated honey bees also 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 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.
And apparently bees can sometimes distinguish harmful fungi from harmless ones, since colonies did not bring in increased amounts of propolis when infected with harmless fungal species. Instead, the colonies relied on physically removing the spores.
However, the self-medicating behavior does have limits. Honey bee colonies infected with pathogenic bacteria did not bring in significantly more propolis - despite the fact that the propolis also has antibacterial properties. "There was a slight increase, but it was not statistically significant," Simone-Finstrom says. "Now we know that this is a characteristic worth promoting, because it seems to offer the bees some natural defense."
The paper, "Increased collectionafter parastie challenge: a case of self-medicaton in honey bees?" was co-authored by Dr. Marla Spivak of the University of Minnesota and published March 29 in PLoS ONE. The research was funded by the National Science Foundation .