Influences of pupal presence and worker number on the survival and development of pharaoh ant (Monomorium pharaonis) brood under laboratory conditions

초록

Social isolation and inadequate group composition can severely impair brood survival in eusocial insects due to the loss of social interactions. Establishing small artificial colonies is a prerequisite for studying developmental biology and functional genetics in ants; however, the minimal social requirements for effective brood rearing remain poorly understood. In this study, we investigated the impact of social composition - specifically the presence of pupae and worker abundance - on the survival and development of intact eggs within laboratory-maintained sub-colonies of the pharaoh ant, Monomorium pharaonis. Our analysis revealed that supplementing colonies with pupae significantly enhanced brood survival and accelerated larval development. Furthermore, we identified that sufficient worker numbers improve brood success, supporting the existence of a viable colony size. Our data suggest that while a sufficient workforce is essential for brood care, further increases in worker number do not yield proportional gains in rearing efficiency under our laboratory conditions. These results indicate that establishing favorable rearing conditions depends on achieving a functional demographic balance, particularly through pupal supplementation and an appropriate worker ratio. This study highlights the vital role of colony demographics and pupal presence in ant development, providing a practical framework for brood manipulation and ensuring baseline survival for future functional genetic applications.

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