Clique formation of super-sister honeybee workers (Apis mellifera) in experimental groups

Summary One day old honeybee workers (Apis mellifera) were observed in small experimental groups (10 workers per group). These groups were either composed of offspring workers of singly inseminated queens (super-sister groups) or multiply inseminated queens (mixed groups). The groups thus consisted of either super-sisters or a mix of super- and halfsisters. The positions of the individually labelled workers were observed with infrared sensitive video equipment over a 24 h period and analysed with digital image analysis. The spatial distribution of workers in super-sister and mixed groups differed significantly. The distance between super-sister workers was significantly less than in mixed groups (n = 339; p < 0.01). Also the distance of the workers from the group centre was significantly less in super-sister groups as compared to mixed groups (n = 3440, p<0.05). The super-sisters thus formed tighter groups than the groups including half-sisters. A genotypic analysis of the mixed groups with microsatellite DNA markers revealed that workers were significantly more frequently observed next to a super-sister rather than a half-sister (p < 0.001). Irrespective whether this results from kin recognition or not, we expect clique formation to be an important factor for the development of task specialisation among worker bees.Received 26 August 2002; revised 22 April 2003; accepted 25 July 2003.