Ethology of hygienic behaviour in the honey bee Apis mellifera L-(Hymenoptera : Apidae): Behavioural repertoire of hygienic bees

Hygienic behaviour performed by middle-aged worker bees is an important int ranidal task in colonies of the honey bee Apis mellifera (L.). It comprises detecting diseased brood in the larval and pupal stages and removing all s uch infected brood, thereby decreasing the incidence of infection. Hygienic behaviour consists of two task-components: uncapping cells and removing th e cell contents. The aim of this study was to observe bees performing hygie nic behaviour to determine their age at performance of the behaviour and to describe their behavioural repertoire. The bees performing hygienic behavi our were middle-aged bees, younger than foragers. In the colonies where the behaviours of individual bees were observed, all bees performing the hygie nic behaviour were seen to exhibit both the components, though at different frequencies. One behavioural class performed the task of uncapping cells a t higher frequencies than the task of removing cell contents, while another class performed both tasks to the same extent. While these two classes had higher frequencies of the tasks comprising the hygienic behaviour but lowe r frequencies of other common behaviours in their repertoire, a third class of bees included those that performed all behaviours in their repertoire a t similar frequencies. There was no difference in the ages of the bees in t hese three behavioural classes. These results suggest that there is no evid ence of task partitioning among bees performing the hygienic behaviour. The segregation observed could, however, be based on their response thresholds to the stimulus and/or on their ability to discriminate the various cues e manating from the dead brood.