Pollen grains in honeys produced by Tetragonisca angustula (Latreille, 1811) (Hymenoptera: Apidae) in tropical semi-arid areas of north-eastern Brazil

The flora of north-eastern Brazil offers a source of nectariferous–polliniferous species that support many native pollinators. However, few studies have examined the plant–Meliponini interaction, especially from the melissopalynological aspect. We assessed the flora exploited by Tetragonisca angustula in two caatinga (dry vegetation) areas in the Brazilian semi-arid region through pollen analysis of honeys with the goal of answering the following questions: (a) What are the most representative pollens found in the honeys? (b) Do certain pollen types function as regional geographic markers? (c) What are the characteristics of the trophic niche of T. angustula in these areas? The honeys ( n = 27) were collected every month from October 2010 to December 2011 in Itaberaba and Ruy Barbosa, diluted in tepid water and 95 % ethanol and subsequently acetolysed. The results revealed 67 pollen types in the honeys, with 25 common to both study areas and most of them belonging to the family Fabaceae (>10 types). The most frequent pollen types were Heteropterys , Mikania , Myrcia , Prosopis juliflora and Solanum for Itaberaba and Heteropterys , Mimosa tenuiflora , P. juliflora , Schinus , Senna macranthera , Solanum and Syagrus coronata for Ruy Barbosa. Anadenanthera colubrina , Poincianella pyramidalis and Ziziphus joazeiro were considered markers for caatinga flora. The amplitude of the trophic niche varied between 0.36 and 2.55, while the evenness ranged from 0.15 to 0.77, characterising the foraging habit of T. angustula as polylectic with a more homogeneous use of the flora in Ruy Barbosa than in Itaberaba.