Spraying behavior during queen competition in honey bees

In honey bees (Apis mellifera), virgin queens may eject a liquid substance from their abdomens while they are engaged in fatal combat. We investigated the functional significance of "spraying" behavior by staging queen "duels" within colonies housed in observation hives. Spraying occurred in 39.7% of all interactions between rival queens and was recorded in 12 of 15 duels. Workers were highly attracted to the surfaces and individuals contaminated by spraying, forming tight clusters with hundreds of bees in which movement was severely restricted. One or both queens in a pair became immobilized by the workers in 37.5 and 29.2% of all spraying events, respectively, but the queens were never killed by the workers. Conversely, a mobile queen penetrated the worker aggregation and stung an immobilized queen in one-third of the observed bouts. Thus spraying may serve as a fighting tactic by virgin queens to increase their chances of winning by temporarily immobilizing their rivals.[PUBLICATION ABSTRACT]