Long-lived winter honey bees show unexpectedly high levels of flight activity compared to short-lived summer bees

Abstract

In temperate regions, the overwintering success of honey bee colonies, Apis mellifera, depends on the last generations of long-lived bees emerging in autumn, known as winter bees. While the physiological qualities of winter bees and their extended lifespan are well documented, yet literature on their flight activity performance is scarce. Here we studied the flight activity of long-lived winter honey bees and compared their performance with short-lived bees. Using radio frequency identification (RFID), we automatically monitored the number of flights, the total flight duration and the lifespan of 523 honey bees that emerged over the course of a year, including short-lived bees from spring, summer and autumn, and long-lived winter bees. We found that flight activity performance of short-lived bees decreased progressively from spring to autumn for both the number of flights and the total flight duration. Furthermore, we confirm that only a fraction of the bees emerging before winter are long-lived winter bees, with a lifespan of 143.5 ± 23.5 days (mean ± SD). With an average of 37.5 ± 44.2 flights and 12.7 ± 15.5 h of flight, we found that long-lived winter bees were substantially more active than summer and autumn short-lived bees, but performed similar activity than spring short-lived bees. We also found that a small proportion of long-lived winter bees participate in the vast majority of the flight activity of the colony. Our results suggest that the extended lifespan of long-lived winter bees does not affect their flight activity performance, probably explained by their physiological qualities.