Monday, December 10, 2007 - 9:53 AM

Colony-level immunity benefits of resin collection by honey bees (Apis mellifera)

Michael Simone,, University of Minnesota, Ecology, Evolution and Behavior, 1987 Upper Buford Circle, Ecology Building, St. Paul, MN, Jay Evans,, Bee Research Laboratory, Usda-Ars, Bldg. 476, BARC-East, Beltsville, MD, and Marla Spivak,, University of Minnesota, Entomology, 219 Hodson Hall, 1980 Folwell Ave, St. Paul, MN.

This study aimed to determine if the use of resins, complex plant secretions with diverse antimicrobial properties, is a colony-level defense against pathogens by honey bees. The harvesting of antimicrobial compounds from the environment and their use in social nest architecture is an exciting but relatively unexplored colony-level defense. We hypothesize that the presence of propolis within the colony reduces the amount or diversity of pathogenic microbes within the nest and thus results in a lowered physiological investment in the production of antimicrobial peptides in bees throughout the colony. Colonies were experimentally enriched with resin extract from Brazil, resin extract from Minnesota, or were deprived of resin. Larvae and adult bees of known age were collected from each colony for analysis. We measured gene transcript levels of 6 antimicrobial peptides and a lysozyme to determine if the presence of resin in colonies has the effect of down-regulating or decreasing the inducible immune response of individual adult bees. In addition, we measured gene transcripts of the 16S rRNA loci as a generic indicator of the presence of eubacteria, and of two honey bee pathogens. Preliminary results suggested that individual beesí immune systems in resin-poor colonies were up-regulated, as indicated by higher immune-related gene transcript levels. This is likely due to higher bacterial and pathogen levels in the resin-poor colonies, signifying that the lack of resin and presence of microbes caused bees to invest more in the production of energetically costly immune proteins.

Species 1: Hymenoptera Apidae Apis mellifera (European honey bee)