Sensor-Based Monitoring of Intrahive CO₂-Humidity-Temperature Profiles in the Muğla Ecotype Based on Brood and Total Frame Numbers in April, July, and October

Abstract

This study investigates the seasonal dynamics of in-hive carbon dioxide (CO₂), tempera-ture, and humidity profiles in honeybee colonies of the Muğla ecotype (Apis mellifera an-atoliaca) and their relationship with colony performance. Continuous high-resolution da-ta were collected during spring (April), summer (July), and autumn (October) using pho-toacoustic NDIR-based SCD41 sensors installed in 20 standardized Langstroth hives. The collected environmental data were synchronized and analyzed with the number of total bee frames and brood frames, which serve as biological markers of colony strength. The findings indicate that CO₂ values reached up to 13,751 ppm in April when colony brood rearing activities accelerated; gas concentrations exhibited a more stable trend due to ac-tive fanning behavior during the summer months when honey flow and thermal stress peaked; and in autumn, a relative CO₂ accumulation occurred to create a hypoxic envi-ronment within the hive in parallel with winter cluster preparations. Contrary to expected biological assumptions, statistical analyses revealed no direct linear relationship between the number of brood frames or the total bee population and in-hive gas parameters. This demonstrates that the complex ventilation strategies employed by honeybee colonies to maintain homeostasis effectively mask the increased metabolic CO₂ production in the brood area, proving that the system operates in a non-linear thermodynamic equilibrium. The results confirm that in-hive sensor data are not direct population indicators, but rather comprehensive manifestations of adaptive cellular and behavioral responses to environ-mental stressors.