Metabolic rate predicts the lifespan of workers in the bumble bee Bombus impatiens

The rate of living theory posits that higher metabolic rates negatively affect lifespan. This relationship would influence trade-offs among life history traits associated with energy production and allocation. These trade-offs may also apply within a species, resulting in differences among individuals in life history traits. In this study, we use the bumble bee Bombus impatiens to test for a relationship between metabolic rate and lifespan. We measured the resting metabolic rates of workers throughout their lives and noted their lifespans in the laboratory. Our results show that (1) resting metabolic rate inversely correlated with potential lifespan and (2) resting metabolic rate was not affected by age. These results suggest that within a species, individual differences in life-history trade-offs may exist as predicted by the rate of living theory.