Palynology as a Tool to Distinguish between Propolis and Geopropolis: Southern Brazilian Samples

Propolis is a product elaborated by honey bees (Apis) and comprises plant resins, bee wax, glandular secretions of the worker bees and pollen grains. Geopropolis is a product elaborated by stingless bees and comprises similar compounds of honey bees and soil, mud, clay, earth or sand. The present study intends to distinguish between propolis and geopropolis using pollen analysis. A total of 12 samples were obtained in the Southern Brazilian macro-region and processed by standard melissopalynological methodology. All structural components recovered after alcoholic extraction and before acetolysis treatment were evaluated. Four of the eight samples collected in the State of Paraná were prepared by Apis and showed a strong contribution of Asteraceae and Eucalyptus pollen grains. On the other hand, the two geopropolis samples of Tetragonisca angustula contained mainly Cecropia pollen grains, while the samples of Melipona quadrifasciata and Melipona mondury showed a predominance of Melastomataceae pollen grains. The four propolis samples obtained in the Santa Catarina and Rio Grande do Sul States were characterized by a predominant pollen contribution of Asteraceae and Eucalyptus. Additional structured elements in propolis samples comprised frequently plant trichomes and tissue fragments. On the contrary, the geopropolis samples showed high values of spores of fungi, amorphous organic matter, sand or clay and sometimes remainder of resin. In conclusion, the pollen grain spectra do not distinguish between propolis of Apis and geopropolis of stingless bees, but the accessory elements are conclusive.