Pollen Assemblages of Propolis from Stingless Bees in Two Mexican Regions

Seventeen propolis samples from Melipona beecheii, Nannotrigona perilampoides, Plebeia frontalis, Scaptotrigona mexicana, and S. pectoralis in tropical regions of Veracruz and Yucatan, Mexico were analyzed for pollen. All samples were individually placed in a glass jar with EtOH and they were daily shaken for a week. Then they were filtered and acetolyzed. A total of 111 taxa belonging to 55 botanical families were recorded. The best represented families were Fabaceae, Malvaceae, Loranthaceae, Myrtaceae, Asteraceae, and Piperaceae. Most taxa belonged to secondary or original vegetation from tropical evergreen and deciduous forests or cloud forest; some were cultivated plants. The abundant taxa for M. beecheii were Miconia sp., M. bahamensis, M. pudica, and Senna sp., while Piper sp. was abundant in propolis samples from N. perilampoides. Moreover, Heliocarpus appendiculatus, M. pudica, and Struthanthus sp. were frequent for N. perilampoides, P. frontalis, S. mexicana, and S. pectoralis in Veracruz. The highest richness and diversity values (H′) were registered by N. perlampoides, S. mexicana, and S. pectoralis propolis samples. Recovered pollen grains such as Acacia, Alnus, Bursera, Eucalyptus, Fraxinus, Liquidambar, Piper, Toxicodendrom, Ricinus communis, Pinus, Salix, Alnus, and Polypodiaceae are known to produce resins (balsams). Palynological spectra showed intranest contamination by other pollen forage and indicators of disturbed microhabitats. Additionally, in all propolis assemblages we found fungal spores, fungal hyphae, plant debris, and scarce clays.