Queen brood care behavior is plastic and socially regulated in an annually eusocial insect

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Abstract The ability of organisms to shift behaviors in response to their environment, known as behavioral plasticity, is a key facet of survival in many environmental contexts. Organisms living in social groups additionally exhibit behavioral plasticity with changes to the social environment. In eusocial insects, queens often transition away from brood care toward reproductive specialization as workers assume caregiving responsibilities. However, the extent to which queens retain behavioral plasticity following this transition varies among eusocial insects and remains poorly understood in bumble bees. In this study, we examined plasticity in bumble bee queen brood care in response to total worker loss, specifically exploring two key behaviors: feeding and incubation. We further asked whether queens become less plastic across colony development​ stages by examining colonies at ​early, middle, later​, and ultimately mature developmental stages. We found that across all nest developmental stages explored, queens retained their ability to perform brood care. Further, we found that queens regulate feeding and incubation behaviors differently, displaying a greater plasticity in incubation than in feeding following changes in social conditions. Broadly, this work highlights how life-history transitions do not necessarily mark the end of an organism’s behavioral plasticity.