Pollen Analysis of Bees’ Crop Nectar as an Effective Method to Determine Nectar Sources: Comparison with Traditional Approaches

Identifying the nectar sources of stingless bees is essential for understanding plant–pollinator interactions and for promoting sustainable meliponiculture. Traditionally, this has been achieved through melissopalynological analysis of honey; however, this approach has certain limitations. Here, we aimed to evaluate whether pollen analysis of bee crop nectar can reliably identify nectar sources for stingless bees. We conducted palynological analyses of honey samples (n = 12) and crop nectar samples (n = 757, considering individual foragers), and conducted field surveys to determine nectar sources for the stingless bee Tetragonula pagdeni in West Bengal, India. From the honey analysis, 42 pollen types were identified, with Eucalyptus tereticornis as the predominant pollen type. In contrast, 67 pollen types were recorded from the crop nectar samples. The most frequently occurring pollen types were Acacia auriculiformis, Borassus flabellifer, Eucalyptus tereticornis, Peltophorum pterocarpum, Tridax procumbens, and Ziziphus mauritiana. Through field surveys, 73 plant species were identified as nectar sources. By integrating these methods, 85 plant species were recognised as nectar sources for stingless bees. The findings indicate that palynological analysis of bees’ crop nectar is an effective method for identifying the nectar sources of a bee species. Furthermore, combining palynological analysis of crop nectar with melissopalynological analysis of honey provides a more comprehensive and potentially more accurate assessment of nectar sources than reliance on honey analysis alone.