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Abstract The mechanisms that underlie senescence are not well understood in insects. Telomeres are conserved repetitive sequences at chromosome ends that protect DNA during replication. In many vertebrates, telomeres shorten during cell division and in response to stress and are often used as a cellular marker of senescence. However, little is known about telomere dynamics across the lifespan in invertebrates. We measured telomere length in larvae, prepupae, pupae, and adults of two species of solitary bees,Osmia lignariaandMegachile rotundata. Contrary to our predictions, telomere length was longer in later developmental stages in bothO. lignariaandM. rotundata.Longer telomeres occurred after emergence from diapause, which is a physiological state with increased tolerance to stress. InO. lignaria, telomeres were longer in adults when they emerged following diapause. InM. rotundata, telomeres were longer in the pupal stage and subsequent adult stage, which occurs after prepupal diapause. In both species, telomere length did not change during the 8 months of diapause. Telomere length did not differ by mass similarly across species or sex. We also did not see a difference in telomere length after adultO. lignariawere exposed to a nutritional stress, nor did length change during their adult lifespan. Taken together, these results suggest that telomere dynamics in solitary bees differ from what is commonly reported in vertebrates and suggest that insect diapause may influence telomere dynamics. 

Stress can influence lifespan in both positive and negative ways, depending on exposure intensity and duration. However, mechanisms driving positive stress effects on lifespan remain poorly understood. Prolonged hypoxia extends the lifespan of overwintering prepupal Megachile rotundata. Here, we explore telomere length and reduced oxidative stress as potential mechanisms of this extended lifespan. We hypothesized high antioxidant capacity under hypoxia reduces oxidative damage and telomere loss. We exposed prepupae to 10, 21 or 24% oxygen for up to 9 months and measured monthly survival, telomere length, antioxidant capacity, and lipid peroxidation across treatment duration for prepupae and adults. After 9 months of exposure, survival was highest in hypoxia and lowest in hyperoxia. Telomere length did not differ among oxygen treatments but increased in adults compared to prepupae. Total antioxidant capacity and lipid peroxidation showed no significant differences among oxygen treatments, suggesting compensatory responses to maintain baseline oxidative levels. 

The disposable soma theory posits that organisms allocate limited resources between reproduction, maintenance, and growth, resulting in trade-offs, particularly as they age. In this study, we examined age-related reproductive senescence in Megachile rotundata, a solitary bee and important agricultural pollinator. We hypothesized that, similarly to social bees, aging females would show declines in foraging behavior and reproductive fitness. Contrary to this hypothesis, we found no evidence of reproductive senescence in M. rotundata within the timeframe observed. Instead, older females increased their foraging rate, leading to larger provisions and offspring. We also observed that older bees exhibited improved foraging efficiency, likely due to learning and muscle physiology changes. Furthermore, ovarian development showed no decline with age, indicating that reproductive capacity remains stable throughout the observed timeframe. Our results challenge conventional assumptions about reproductive senescence in solitary bees and suggest that older M. rotundata may contribute to more efficient pollination, with implications for pollinator management. This study provides new insights into the aging process in solitary bees, emphasizing the need for further research into the mechanisms behind age-related behavioral and reproductive changes. 

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 beeMegachile 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.