Carl Hayden Bee Res. Ctr., USDA-ARS, 2000 E. Allen Rd. Tucson, AZ-85719, USA.
Honey bees, Apis mellifera, reproduce via swarming in which a queen and thousands of workers fly en masse to a new colony nest site. Good, secure nest sites are rare and difficult to locate; consequently, honey bees have evolved an elaborate system for chemically locating and communicating information about potential nest sites. Previous studies have shown that Nasonov pheromone is the master chemical messenger during this process and that other bee pheromones, such as queen pheromone, as well as plant and animal odors, play little or no role in this communication. However, honey bee observers have noted that swarms are highly attracted to used hive equipment and to cavities that were previously inhabited by colonies. Sources of hive odors were divided into categories of: old dark comb used for rearing brood, non-comb residues remaining in hive cavities; and propolis, the material used for universal caulking and antisepsis. These odor sources were tested in combinations and with Nasonov pheromone in direct competition experiments and in crossover experiments to determine a hierarchy of attraction for swarms. Nasonov pheromone tops the hierarchy and its presence renders all other attractants superfluous. If Nasonov pheromone is not present, as in cavities before discovery by swarm scouts, old dark brood comb is the most important attractant. Finally, both non-comb cavity residues from previous colonies and propolis are attractive to swarms in the absence of comb. This last is the most common situation in nature, because wax moths usually render combs into a mess of frass and silk. Thus, honey bees appear to have a distinct hierarchy of odor cues that attract them to nest sites, a hierarchy based on criteria reflecting overall nest quality.