Honey bee worker longevity with and without reproductive suppression by the queen

Aging is inherent to all organisms. One common finding in different species is a negative correlation between reproduction and lifespan. However, in social insects, the inverse is true: Individuals that specialize on reproduction far outlive their non-reproductive workers. This is particularly true for the honey bee (Apis mellifera), in which summer workers live 5-7 weeks but queens can live over several years. Several studies have directly compared queens and workers to identify the proximate causes of this differential in life expectancy but these comparisons are problematic because queens and workers differ in many aspects that are unrelated to aging. In this study, we expand these efforts and focus on the effects of reproductive activity on the longevity of honey bee workers. We hypothesize that there is a connection between reproductive social structure, behavior, and mortality. Three observation hives were set up: a control hive containing a queen and two treatment hives without queens, one including brood. Equal sized cohorts of newly-emerged workers were marked with distinctive number tags and introduced to the hives. Mortality and different social behaviors were compared between the treatments to investigate the life history of reproductive workers, as an intermediate between non-reproductive workers and queens. In addition, worker longevity was also monitored in six queenright and six queenless small experimental hives. Our results contribute to the understanding of aging plasticity in the honey bee and how social structure, behavior, and aging are linked through social roles in the colony.