Reallocation of labor in honeybee colonies during heat stress: the relative roles of task switching and the activation of reserve labor

Abstract.

Social insect colonies reallocate labor in response to changing environmental circumstances. This study addresses the reallocation of labor by middle-age honeybees in response to heat stress. I tested the hypothesis that the additional labor required to respond to heat stress is obtained by reallocating labor away from unrelated tasks (task switching), activating reserve labor, or both. I found that task switching plays the primary role in this process. Although self-grooming decreased, other indicators of inactivity increased or remained unchanged, leaving the role of reserve labor ambiguous. I also explored the relative importance of specialists versus generalists in the production of work. Wax working, a common task among middle-age workers, was used as a model. I found that although there is a distinct group of wax specialists, they contributed only 19.5% of the total number of wax-working observations. Most wax working was found to be performed by generalists. In addition, I tested for a distinct group of reserve specialists. I found that although activity rates differed between individuals, there was no evidence for a stable group of reserve specialists. The high rate of task switching, in both stressed and unstressed environments, observed in this study highlights the possible significance of frequent task quitting as an organizing principle in the allocation of labor in social-insect colonies.