Stingless bees prefer many small rather than few large pollen sources

Researchers from Australia and Germany have published the results of an experiment on the pollen resources used by the stingless bee Tetragonula carbonaria in forests and farms of sub-tropical Australia.

They used a genetic bar-coding technique to identify the pollens from storage pots in 57 colonies collected at seven sites each season over two years. They identified pollen from 302 plant species in 72 families. Introduced species such as the common Blue billygoat weed (Ageratum houstonianum) and Wild radish (Raphanus raphanistrum) were common pollen sources in both orchards and forests.

Even pollen from some wind-pollinated grasses and sedges were used. A greater diversity of pollen types was found in forests compared to farms. Pollen from many plants in the Myrtaceae family such as Corymbia, Eucalyptus and Melaleuca spp. were common as were Fabaceae and Proteaceae species. The stingless bees aim for diversity in pollen diets by foraging on “many small” rather than a “few large” pollen sources each season, regardless of land use.

The senior author, Rachele Wilson, collecting pollen from a stingless bee hive

The bees aim for a diverse, nutritionally-balanced pollen diet to ensure colony performance. The researchers recommend that managers and beekeepers should ensure colonies have access to a variety of floral resources year-round. This may be achieved through planting of key plants identified in this study. They also suggest that weeds be allowed to flower in the orchard. Land managers may consider planting in unproductive areas such as riparian zones, edges or between crop rows.

Rachele S. Wilson, Alexander Keller, Alison Shapcott, Sara D. Leonhardt, Wiebke Sickel, Jane L. Hardwick, Tim A. Heard, Benjamin F. Kaluza and Helen M. Wallace (2021). Many small rather than few large sources identified in long-term bee pollen diets in agroecosystems.

Agriculture, Ecosystems & Environment. Free copy of this article available here for download before 26 February:

These stingless bees are well-nourished with fa-voured weeds, riparian trees and macadamia trees