Pollen diversity in urban honey: implications for bee foraging behaviour and urban green space planning

Abstract

Understanding the diversity of nectar sources in urban honey samples is crucial for effectively managing honey bee (Apis cerana indica Fabricius, 1978.) colonies and promoting pollinator health. This study analysed honey samples from various urban locations in Bangalore to assess pollen diversity, foraging behaviour, and the significance of urban flora in supporting beekeeping practices. A total of 39 pollen types were identified, with 62.50% of samples being unifloral, predominantly from Eucalyptus sp., followed by Casuarina equisetifolia, Areca catechu, Citrus sp., Mallotus philippensis, Cocos nucifera, and Ocimum sp. Multifloral samples (37.50%) highlighted the diverse diet available to urban bees, promoting biodiversity within urban landscapes. Major plant families contributing to pollen content included Myrtaceae, Arecaceae and Fabaceae. Seasonal variation in pollen composition reflected shifts in dominant nectar sources, with the monsoon season characterized by Casuarina equisetifolia, Areca catechu, Citrus sp., Mallotus philippensis, and Cocos nucifera, while winter saw Eucalyptus sp. and Ocimum sp. as predominant sources, and summer featured Pongamia pinnata. Cluster analysis found high similarity in pollen composition in honey samples from Bagalur, Yelahanka and M S Palya but distinct pollen in GKVK, suggesting unique conditions and emphasizing the importance of considering spatial variations in beekeeping practices and conservation strategies. This research underscores the importance of floral diversity in sustaining urban bee populations and provides guidance for urban planning and policy decisions to promote pollinator health and urban sustainability.