Flower pollen sources of non- Apis bees ( Amegilla zonata , Ceratina binghami , Lasioglossum cavernifrons , Megachile disjuncta , and Xylocopa fenestrata ) in southern West Bengal, India: Insights from pollen load analysis and field surveys

Non-Apis bees (including solitary bees) are highly valued for the essential ecosystem services they provide, and their survival largely depends on the availability of floral resources. However, knowledge of the floral pollen sources exploited by non-Apis bees (especially solitary bees and subsocial bees) remains limited. This study aimed to identify the host plants of selected bee species [viz. Amegilla zonata (blue-banded bees), Ceratina binghami (small carpenter bees), Lasioglossum cavernifrons (sweat bees), Megachile disjuncta (leafcutter bees), and Xylocopa fenestrata (carpenter bees)]. Pollen sources were determined through palynological analysis of pollen loads (scopal, abdominal, and nest-stored pollen), supplemented by field surveys. The solitary bees studied exhibited polylectic foraging behaviour, with pollen diversity being higher in Lasioglossum cavernifrons than in Megachile disjuncta and Xylocopa fenestrata. Crotalaria juncea and Peltophorum pterocarpum were important pollen sources for all species. Brassica juncea, Coccinia grandis, Coriandrum sativum, and Lannea coromandelica were key pollen sources for Ceratina binghami and Lasioglossum cavernifrons, while Luffa acutangula and Luffa aegyptiaca were particularly important for Amegilla zonata. Cajanus cajan served as a vital pollen source for Megachile disjuncta and Xylocopa fenestrata. All selected bees foraged on flowers of native and exotic plants, with both wild and cultivated plants serving as pollen sources. As generalist foragers, these bee species exploited flowers from plants of diverse origins, growth forms, inflorescence types, and floral traits. Overall, these findings provide valuable insights for the conservation and management of these bee species and their habitats, supporting the continued provision of vital ecosystem services.