Metabolic resilience to starvation is shaped by early-life maternal care in bumble bees

Eusocial insects, such as bumble bees, rely on both maternal and alloparental care. During the early development of a colony, queens provide direct care to the brood; however, once workers emerge, sibling care takes over. Bumble bees (Bombus impatiens) offer a great model for studying how rearing conditions shape adult traits. Here, we examined how maternal versus sibling brood care affects starvation resistance in workers. We reared bees under three caregiving conditions: queen (maternal care), a single worker, or five workers. To assess metabolic resilience, adult bees underwent either a 6- or 12-hour starvation period, during which we measured blood sugar concentrations and metabolic reserves. While the number of caregivers influenced body size, starvation resistance was more directly linked to maternal care. Bees reared by queens exhibited greater metabolic flexibility, maintaining stable blood sugar levels and efficiently shifting to alternative fuel sources during starvation. In contrast, those reared by sibling workers showed reduced metabolic adaptability. However, metabolic rates and blood sugar levels remained unchanged under normal conditions, suggesting that maternal investment specifically enhances resilience to nutritional stress rather than altering baseline metabolism. Our study demonstrates that maternal care during development enhances starvation resistance in bumble bees. These findings highlight the lasting effects of early rearing history on stress responses, emphasizing the role of maternal investment in shaping adult metabolic resilience in eusocial insects.