Centripetal pull of workers towards the center of the bumble bee (Bombus impatiens) nest, and robustness of in-nest division of labor

The success of social insects has been attributed to their division of labor; each individual performs different tasks within a colony simultaneously. Different tasks typically take place in different areas throughout the nest, and many species, including bumble bees, exhibit a division of space that correlates with their division of labor. Here we examine the robustness of these spatial zones and the tasks most often performed within them by removing a subset of workers from the colony. We show that when we remove bees that are more likely to reside in the central areas of the nest, the remaining workers move in towards the center. Yet, when we remove bees that reside on the periphery of the nest, there is no significant change in area use by workers. Furthermore, regardless of which bees were removed from the nest, there was no change in the division of labor. We conclude that the mechanism that drives spatial organization in bumble bees is an attractive centripetal force that pulls workers towards the center of the nest, allowing the division of labor to remain unaffected even after a major disturbance.