Individual Differences in Circadian and Behavioral Rhythms of Honey Bee Workers (Apis Mellifera L.).
Giannoni Guzmán, Manuel A.
Agosto Rivera, Jose Luis (Consejero)
Circadian rhythms are oscillations of approximately 24 hours that regulate the timing of behavioral and physiological processes and synchronize them with environmental cues. Although studies in flies and mice have provided unparalleled insights about the cellular and molecular machinery controlling circadian rhythms, little is known about how this machinery benefits organisms in their natural habitat, and how the environment shapes the development and function of the circadian system. Honey bees are an ideal system to address these questions because they exhibit circadian regulation of ecologically relevant behaviors and can be studied in both the field and the laboratory. Here I describe the adaptation of the Drosophila monitoring system for the use of honey bees and social wasps. Using this system, I show that the social control of temperature at ~35°C during the first 48 hours post emergence not only plays a key role in the ontogeny of circadian rhythms, but also has long term effects on the physiological regulation of the circadian clock and life expectancy. Moreover, I discovered that as we move away from the colony’s center, temperature oscillates in a circadian manner, and simulating these oscillations is sufficient to entrain circadian rhythms. A large degree of individual variation in the different circadian parameters was a landmark of all these experiments, which led me to question if it has a functional role in the colony. I hypothesized that this individual variation could provide the basis for a natural form of shift work in bees. Consistent with this hypothesis, I show that there is a large degree of individual variation in foraging and fanning behaviors and that bees form temporal clusters (shifts) that can be organized based on their daily and weekly patterns of these behaviors. Taken together, our findings indicate that colony temperature has a major impact on the development and function of the circadian system. Furthermore, individual variation in the timing of foraging may guarantee a constant influx of resources from the environment, while minimizing individual risk. Variation in fanning behavior may contribute to the stability of colony temperature and could explain the importance of genetic diversity in temperature regulation.