Raw data: Early Post-Eclosion Physiological Remodelling in Tenebrio molitor: Body Condition, Cuticle Tanning and Immune Maturation During the First Week of Adult Life

Abstract The yellow mealworm, Tenebrio molitor L., is a fundamental species in the context of in-dustrial insect farming. However, yet the physiological transition following adult eclosion remains poorly understood. This study provides a comprehensive characterisation of the integrated energetic and immunological remodelling that occurs during the critical first week post-eclosion. This information serves as a fundamental baseline for optimising mass-rearing practices and ensuring experimental standardisation. We monitored body mass, Scaled Mass Index (SMI), and cuticular tanning trajectories (0, 1, 5, and 7 days), alongside cellular (Total haemocyte count, THC) and humoral (Phenoloxidase activity, PO) immunocompetence (2 and 7 days) in both sexes. Results revealed an energetically in-tensive initial phase with significant proportional mass loss between days 0 and 5, fol-lowed by stabilization and improved SMI by day 7. A significant increase in THC of more than twofold was observed as the beetles matured, while the humoral defences remained stable. The maturation of exoskeletons was found to be unaffected by age or sex. However, a negative correlation was observed between cuticle tanning efforts in males and exoskel-eton maturation, indicating that the same resource pathway is utilised in both processes. Sex-specific correlations emerged: females showed a positive relationship between initial reserves and PO activity at maturity, while males exhibited a moderate negative trend. Early adulthood is a phase of coordinated physiological strengthening, preparing the bee-tle for reproduction through synchronised exoskeleton stabilisation and significant cellu-lar immune expansion.