Spatial effects cause task specialization in the honey bee (Apis mellifera)

Task allocation patterns should depend on the spatial distribution of work within the nest and on the movement patterns of workers, however, relatively little research has focused on these topics. This study uses a spatially explicit agent based model to determine whether these factors alone can generate strong biases in task performance at the individual level in honey bees, Apis mellifera. Bees with task biases (specialists) are shown to result from variation in task demand, area of task performance, movement rates, and developmental biases for particular regions of the nest. To date, specialization has been primarily interpreted with the response threshold concept, which is focused on intrinsic (typically genotypic) differences between workers. Response threshold variation and spatial effects are not mutually exclusive, however, and this study suggests that both contribute to patterns of task bias at the individual level. While spatial effects are strong enough to explain some documented cases of specialization; they are relatively short term and not explanatory for long term cases of specialization. In general, this study highlights the central role played by spatial effects and movement behavior in task allocation for social insects that inhabit large complex nests. It further suggests that the spatial layout of tasks, and fluctuations in their demand, must be explicitly controlled for in studies focused on identifying genotypic specialists.