Exploring reproductive strategies and social dynamics: A comprehensive study of Bombus impatiens nests in early colony development

Animals exhibit a variety of unique life history strategies that are linked with fecundity and fitness. For social animals that exhibit brood care, unraveling the balance between personal survival, reproduction, and care for offspring offers crucial insights into social dynamics and evolutionary processes. Bumble bee queens initiate nests alone and carry out all brood care until the emergence of their first workers, who then provide sibling care. Whereas previous studies explored reproductive strategies in the initial nesting stages and potential cues for reproductive transitions, a comprehensive characterization of bumble bee queens reproductive strategies and their relationship with developing brood in early nest development has been under-studied in modern research. In this study, we examine the reproductive rates of Bombus impatiens queens, quantifying egg-laying, brood and nest development, and the timing of events within the nest. We determined that queens demonstrate a consistent egg-laying pattern during the first few weeks of colony development. Within the first two weeks of nest establishment, queens lay eggs for 3-5 days, then cease egg-laying for an average of 8 days, then reinitiate once their oldest brood reaches late-stage development (predominantly 4th instar/pupae). Moreover, reproductive event timing appears to be socially regulated through interactions with developing brood, as queens with prematurely added late-stage brood to their nests re-initiation sooner. This study enhances our understanding of reproductive and social dynamics within the early stages of bumble bee colonies.