Spatio-temporal patterns of diversity and distribution of common Megachile bees across agroclimatic gradients in Eastern India

Bees of the genus Megachile (Megachilidae; Hymenoptera) are among the most efficient pollinators of wild and cultivated plants, yet their diversity, distribution, and seasonal dynamics remain inadequately documented across varied agroclimatic landscapes in India. Despite their recognized contribution to crop pollination, previous studies have largely overlooked spatial and seasonal variation in Megachile assemblages, especially in Eastern India. The present study addresses this knowledge gap by conducting a two-year field survey to assess the diversity and distribution patterns of Megachile bees across six agroclimatic zones of West Bengal, India. A total of nine Megachile species were recorded, with M. lanata and M. disjuncta being the most abundant and widely distributed across all zones. Notably, the New Alluvial Zone exhibited the highest total abundance ( N = 198), while the Red Laterite Zone supported all nine species with high species diversity (H = 1.99) and evenness (E = 0.908). Seasonal trends revealed a pronounced peak in bee activity in late winter/early summer and a significant decline during the monsoon and early winter months. This study provides a regional biogeographical baseline for solitary bee monitoring, agroecological research, and future investigations into bee–plant interaction networks in India’s changing agricultural landscapes.