Effect of "spraying" by fighting honey bee queens (Apis mellifera L.) on the temporal structure of fights

Young queens start a new colony either without (independently) or with the help of workers (dependently). When colony reproduction is dependent and young queens are produced in excess, conflicts among queens are predicted to occur. Honey bee colonies reproduce dependently by swarming. The mother queen leaves with a “prime swarm” before daughter queens reach adulthood. Several young queens are produced, and often fight to death after emergence. Surviving queen(s) inherit the established nest or a portion of workers which then depart in an “afterswarm”. Honey bee queens show traits considered to be adaptations for fighting and conflict with other queens, such as early venom production and fast development. During fights one of the queens often releases rectal fluid. The function of this “spraying” behaviour is unclear. Possible functions of spraying are to affect worker intervention in fights, to act as a chemical weapon, or to interrupt fights. We staged fights between 24 queen pairs to investigate the temporal pattern of behaviour in spraying and non-spraying fights. Spraying occurred in 67% of the fights, usually upon physical contact, and it resulted in at least temporary separation of the queens in 81% of the spraying fights. Spraying fights were characterized by a significantly lower proportion of time spent in escalated aggression than non-spraying fights and a significantly shorter first escalated bout. This provides quantitative evidence that spraying interrupts fights and suggests that its function is to provide a temporary respite to the spraying queen.