Linking early-life performance and lifespan in the solitary bee, Megachile rotundata

Performance tends to decline with age. Yet, performance, including muscle function, stress tolerance, and energetics, can vary widely among individuals of the same age, showing that chronological age does not always represent biological age. To better understand the underpinnings of aging, we need to better understand what drives some individuals to age faster than others. However, first we need to be able to predict whether an individual will have a long or short lifespan. In this study, we conducted a longitudinal study to track how individual-level locomotor activity, cold tolerance (chill coma recovery time), and metabolic rates change with age, and whether early-life performance is linked to lifespan using the solitary bee, Megachile rotundata. We found that only locomotor activity and chill coma recovery times decline in old adults, while metabolic rates did not change with age. Early-life high locomotor activity, low cold tolerance, and low mass at emergence are linked to shorter lifespans in females, while metabolic rates did not change with age regardless of sex. These results show that how an individual performs early in life can explain some of the variation in lifespan in a population. Finally, these results also add to the evidence that not all traits decline with age and shed new light on sexual dimorphism in physiological traits and aging.