Senescence and early-life performance as predictors of lifespan in a solitary bee.

Performance tends to decline with age, including muscle function and stress tolerance. Yet, performance can vary widely among individuals within the same age group, showing that chronological age does not always represent biological age. To better understand ageing, we need to examine what drives some individuals to age faster than others. In order to achieve this, 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 tracking individual-level locomotor activity, chill-coma recovery time, and metabolic rates, and assessed whether early-life performance is linked to lifespan using the solitary bee Megachile rotundata. We found that locomotor activity and chill-coma recovery times decline in old adults. However, resting metabolic rate did not change with age. We also found low cold tolerance and low mass at emergence in early-life are linked to shorter female lifespans, showing that early-life performance can explain some of the variation in lifespan in a population. Finally, these results also show that not all traits decline with age within the same species, and shed new light on sexual dimorphism in physiological traits and ageing.