Comparative seasonal plant diversity and leaf foraging pattern of leafcutter bees (Megachilidae: Hymenoptera) in urban, semi-urban and agricultural areas of Eastern India

Abstract

The leafcutter bees, Megachile spp. (Megachilidae: Hymenoptera) serve as a significant pollinator in ecological systems. They collect leaf discs to enclose their brood cells. Nevertheless, our current understanding of using plants as nesting resources in various ecosystems in different seasons, essential for their conservation, needs to be improved. The seasonal and landscape-level alterations have significant impacts on leafcutter bees, influencing species richness, abundance, community composition and leaf foraging behaviour. This study underscores the critical role of different seasons and landscape characteristics in shaping the leaf-foraging behaviour of leafcutter bees. We noted that semi-urban areas (151 different plant species recorded with cut leaves), with their greater landscape heterogeneity and high-quality habitats, supported higher species richness and abundance of leafcutter bees. In contrast, fully urban (49 different plant species recorded with cut leaves) and intensively agricultural landscapes (85 different plant species recorded with cut leaves) posed challenges to the survival of these bees due to habitat loss and fragmentation. We also found that during early autumn, leafcutter bees emerged and constructed ephemeral nests, intensifying leaf-cutting behaviour, whereas the summer and monsoon seasons exhibited a heightened activity, with bees building seasonal nests and gathering leaf and other essential resources extensively. In winter, leafcutting ceased as these bees entered into dormant conditions, seeking shelter in their nests for insulation and protection. This study provides valuable insights into the foraging patterns and habitat preferences in different seasons of leafcutter bees, contributing to the broader understanding of pollinator ecology in changing landscapes and environments.