Seasonal and landscape effects on plant diversity and nutrition of bee-collected pollen and bee bread

Honey bee (Apis mellifera) nutrition is crucial for colony health and productivity. However, the nutritional profiles of pollen and bee bread collected from agricultural, urban, and rural landscapes remain unclear. This study examines the seasonal and landscape effects on plant diversity and the nutritional composition of bee-collected pollen and bee bread, focusing on protein, carbohydrates, lipids, and elemental content. Metabarcoding analysis revealed that species richness was higher in urban landscapes, whereas species richness and evenness were higher in rural landscapes. Plant species composition varied across landscapes and seasons. Nutrient analysis showed that pollen and bee bread contained higher protein levels in summer compared to fall. Lipid content was higher in rural fall pollen than in urban summer samples, reflecting significant seasonal and landscape effects, while bee bread exhibited higher lipid content in rural landscapes. Carbohydrate content in pollen was higher in fall and in rural landscapes, and bee bread showed a landscape effect with higher carbohydrates in rural areas. Elemental analysis indicated that sulfur varied with season, whereas phosphorus, iron, and manganese were influenced by both landscape and season. Potassium, calcium, magnesium, zinc, and copper showed significant landscape × season interactions, while sodium showed no significant variation. The mineral composition of bee bread mirrored that of pollen. These findings highlight the dynamic interplay between landscape, season, and nutrient availability, offering valuable insights for beekeepers to optimize colony nutrition and emphasizing the importance of landscape diversity in supporting honey bee health.