Comparative Study on Nest Density, Habitat Preference, and Nest Architecture of Tetragonula nr. pagdeni Schwarz and Tetragonula nr. shubhami Viraktamath in the Lateritic Zone of Eastern India

Abstract

This study documented the nest density, nesting site, and nest architecture of two poorly studied stingless bee species, Tetragonula nr. pagdeni Schwarz and Tetragonula nr. shubhami Viraktamath, from the lateritic zone of eastern India. Three 100×100 m plots were sampled from each surveyed village to determine the nest density. The external architecture of 57 nests was described, and 12 nests were dissected to observe their internal structure. The average nest density of T. pagdeni (0.88±0.75 nests/ha) was three times higher than T. shubhami (0.29 ± 0.57 nests/ha). T. pagdeni showed the highest nest density in Bankura (1.30 ± 0.75 nests/ha), a district with greater forest cover, while T. shubhami reached higher values in Birbhum (0.52 ± 0.67 nests/ha), an industrialized district with less forest cover. Both species showed a higher frequency (~65%) of nests in man-made structures than trees (~35%) and exhibited a tendency of building south-facing nests (~37‒42%). There was no significant variation in the nest’s external architectural features between them. The nest height indicated a high degree of overlap between the two species, although T. shubhami reached greater heights (237.00 ± 95.64 cm). Both utilize cavities of similar size (p > 0.05), but T. shubhami built significantly (p < 0.05) larger brood cells and food storage pots. Number of guard bees was related (r = 0.87; p < 0.001) to nest’s entrance size, expressing an adjustment to maintain effective colony defense. Despite their flexibility in using cavities, both Tetragonula species nest in tree hollows in regional forests. So their long-term persistence depends on the preservation of their habitats and the conservation of native trees.