Task repertoires of hygienic workers reveal a link between specialized necrophoric behaviors in honey bees

The ecological success of social insects is often attributed to their complex social organization and division of labor. Much previous work has investigated the extent to which individual workers within colonies specialize on certain tasks, which presumably increases colony efficiency. Fewer studies have investigated the extent to which individual biases for multiple related tasks adaptively shape division of labor. Here, we focus on honey bee (Apis mellifera) workers that perform hygienic behavior, the detection and removal of diseased larvae in order to reduce pathogen transmission within the hive. We individually marked workers observed performing this rare task and tracked their behavior over three days to fully characterize their task repertoires. We then compared the task repertoires of workers who specialized on hygienic behavior to generalist workers who occasionally perform hygienic behavior to identify additional task biases in hygienic specialists. We show that workers specialized in hygienic behavior are much more likely to also specialize in removing dead adult bodies from the hive, a task that is also associated with colony defense against disease. Our results demonstrate that individual specialization in one task can predict specialization in another related task. We argue these associations represent a type of specialization in multiple tasks that may be an important aspect of how insect colonies adaptively allocate their workers. Any animal group that divides up work among individuals faces the challenge of figuring out the best way to allocate workers towards certain tasks. One mechanism by which large groups can increase their efficiency is by utilizing specialized workers dedicated to a single task. However, it has also been suggested that if multiple tasks require similar skills or are spatially associated with one another, then group efficiency can be further increased by using the same set of workers to perform those tasks as well. Here, we show that honey bee workers specialized in removing dead larvae from the brood zone of the hive are much more likely than bees of the same age to also specialize in removing dead adults from the bottom of the hive. We suggest that this task association has implications for colony fitness and exemplifies an understudied component of how social insect colonies allocate their workers.