Abstract:
Apis cerana, the native honeybee species of Sri Lanka, plays a pivotal role as a primary pollinator
in both agriculture and biodiversity. However, environmental stress, particularly fluctuations in
temperature (T) and relative humidity (RH), can negatively affect colony health and hive stability,
increasing the risk of colony migration. Passive thermal insulation offeresa potential low-cost,
eco-friendly solution, yet it remains understudied in Apis cerana management. This study
evaluated the influence of internal and external temperature and RH on Apis cerana colonies and
assessed the effectiveness of passive insulation. Ten healthy colonies of similar strength were
housed in eight-frame hives and randomly assigned to treatments. Colonies were maintained
under identical conditions within the same apiary. Two natural insulating materials, wood
shavings and clay brick particles, were applied around hive walls and beneath the roof.
Temperature and RH were recorded using digital sensors (DHT22) placed centrally inside the
hives. Colonies were inspected one day intervals, and photographic monitoring was conducted
biweekly to assess the brood area, bee coverage and comb construction. Optimal internal T and
RH conditions for colony stability were identified as 33–36 °C and 60–70%, respectively.
Statistical analysis was performed using one-way ANOVA to compare internal and external
environmental conditions. Hives with wood shavings maintained an average internal
temperature of 33.51 ± 0.11 °C and RH of 76.66 ± 2.03%, with significant differences from
external conditions (temperature p = 0.00397; RH p = 3.37 × 10⁻¹⁰). Hives with brick insulation
recorded an average temperature of 34.43 ± 0.12 °C and RH of 75.73 ± 0.24%, also showing
significant differences (temperature p = 0.00048; RH p = 0.00034). These findings confirm that
passive insulation effectively regulates hive microclimate and reduces environmental stress,
supporting its application in sustainable, low-cost beekeeping, particularly for rural communities,
while contributing to the growth of Sri Lanka’s apiculture sector.
