Temporal variation in group aggressiveness of honeybee (Apis mellifera) guardsHadassah Troen, Irit Dubrovsky, Ram Tamir and Guy Bloch
Department of Evolution, Systematics and Ecology, The Alexander Silberman Institute of Life Sciences, The Hebrew University of Jerusalem, 91904 Jerusalem, Israel
(Received 29 October 2007 - Revised 5 December 2007 - Accepted 5 December 2007 - Published online 27 February 2008)
Abstract - Little is known about the temporal organization of defensive behavior in honeybees. We studied "guards", the best-characterized class of colony defenders. We synchronized small groups under a light-dark illumination regime (LD), and video recorded their aggression toward an intruder bumblebee worker. In 1 out of 3 trials (each trial with a different source colony), the latency before the first attack was longer during the night in LD, or subjective night in constant conditions (DD); a similar trend was observed in DD in the two other trials. In 2 out of 3 trials, the number of stinging attempts varied with highest levels during the day in DD, but not in LD. There was a similar trend for the number of biting events. These findings reveal temporal variation in aggression under constant conditions, consistent with the hypothesis that the circadian clock influences guard aggressiveness. Nevertheless, the variability between LD and DD and across colonies calls for additional studies before reaching a definitive conclusion.
Key words: honeybees / aggression / colony defense / circadian rhythm / division of labor
© INRA, DIB-AGIB, EDP Sciences 2008