The "Dance or Work" Problem: Why Do not all Honeybees Dance with Maximum Intensity

A honeybee colony has to choose among several nectar sources in the environment, each fluctuating in quality over time. Successful forager bees return to the hive and perform dances to describe the food sources they have found. Each dancer tries to recruit other forager bees to fly to the source it has found. Some individual dancers clearly dance longer for higher quality sources, other dancers distinguish little between poor and good sources; presumably the differences are genetically based [6]. Our multi-agent simulation showed that this individual heterogeneity results in optimal collective exploitation of the environment. Under all tested environmental conditions near-natural heterogeneous colonies worked more efficiently than artificially homogeneous ones. In heterogeneous colonies, dances last sufficiently long to recruit an appropriate number of waiting dancefollowing bees. In homogeneous colonies with good discriminating bees, the dances last longer than is efficient; the extra dancing decreases net food gains per time. The honeybee (Apis mellifera L.), an eusocial insect, lives in colonies of up to tens of thousands of individuals. The colony structure is self-organized, with no central regulatory unit. The individuals show age-polyethism, division of labour and task partitioning ([4]). A cohort of bees specialized on the same task is called a “temporal caste”. The two temporal castes we modelled are the forager bees and the receiver bees. Forager bees fly out of the hive to collect nectar, pollen, water or resins in the surrounding environment. The forager caste is subdivided into scouts, who explore for new food or other resources, and into foragers in the strict sense, who visit “known” resources. Nectar receiver bees wait near the hive's entrance to accept nectar from the returning forager bees. This nectar is then processed and stored in the colony as honey. The colony as a whole continually chooses among different nectar sources in the environment, each with fluctuating food quality. The quality q of source i at a given moment can be expressed by the equation [6]: qi= g−c c . (1) The “Dance or Work” Problem: Why Do not all Honeybees Dance with Maximum Intensity Ronald Thenius, Thomas Schmickl, and Karl Crailsheim Department for Zoology, Karl-Franzens University, Graz, Universitätsplatz 2, A-8010 Graz, Austria [email protected] [email protected], [email protected]