Nest architecture and nesting site preference of Tetragonula iridipennis Smith in different Agro-climatic regions of Karnataka, India

Abstract

The present study was conducted during 2024-25 to investigate the nest architecture and nesting site preferences of the stingless bee, Tetragonula iridipennis Smith across three agro-climatic regions of Karnataka-Northern Dry Zone (NDZ), Southern Dry Zone (SDZ) and Southern Transitional Zone (STZ). Survey was carried out during winter and summer season to record external and internal nest characteristics. Stingless bees preferred enclosed cavities such as wall crevices, wooden boxes, meter boxes and tree hollows, with nest heights ranging from 0.95 to 1.76 m. Entrance tubes were predominantly oval or elliptical, showing regional variation in length (63.22-86.89 mm in SDZ, 20.70-22.80 mm in STZ and 12.92 mm in NDZ) and orientation (south in SDZ, east/north in STZ, south/north in NDZ). Internally, pollen pots were located near the entrance, brood cells at the centre and honey pots on the periphery. Pollen and honey pots were largest in SDZ, whereas NDZ colonies had smaller pots but higher brood cell density, indicating adaptive strategies to local resource availability. Seasonal variation was minor. The study demonstrates that T. iridipennis maintains a stable nest architecture while exhibiting adaptive structural variations in response to regional climatic and ecological conditions, providing insights for conservation and management of stingless bees in Karnataka.