<p>Diapause is an adaptation that allows many insects to survive adverse environmental conditions. While diapause-associated trade-offs with reproduction are well-documented, its potential impact on lifespan and long-term adult physiology remains poorly understood. In this study, we used <i>Megachile rotundata</i>, a bivoltine solitary bee species with facultative diapause, to investigate the effects of prepupal diapause on adult lifespan and physiology. We compared individuals that underwent diapause to those that did not. Our findings reveal a trade-off between prepupal diapause and adult lifespan, with diapause females exhibiting shorter adult lifespans. Newly-emerged females showed no differences in immune response capacity but females that emerged from diapause had higher levels of some measures of oxidative stress and slightly elevated <i>prothoracicotropic hormone</i> (<i>PTTH</i>) expression. These results highlight the physiological consequences of alternative developmental pathways and provide new insights into how diapause strategies shape life-history traits in insects.</p>