Pollen types in honey produced in caatinga vegetation, Brazil

Abstract

Honey samples produced in the years 2010 and 2011, in an area of caatinga vegetation in the semi-arid region of Piauí State (Brazil), were analyzed using microscopy in order to track their botanical origin by the pollen grains present. Samples (19) were dissolved in ethanol and acetolyzed. The absolute concentration of pollen grains was obtained by comparison with the exotic marker Lycopodium clavatum L., and at least 500 pollen grains were counted per sample. The most diverse families were Leguminosae, Euphorbiaceae, Rubiaceae, and Myrtaceae, reflecting the characteristics of the semi-arid region and the caatinga, including endemic species. Samples from February (2010) showed a greater richness of pollen types, which is probably associated with the onset of the rainy season. Even during the dry season, there was honey production, with a considerable diversity of pollen types. This indicates that there are plant species in flower during the dry season that are important to sustaining bee colonies. Mimosa caesalpiniifolia and Pityrocarpa moniliformis were the only predominant pollen types; Coutarea and P. moniliformis were the secondary types. The pollen types Borreria verticillata, Combretum, Croton, Herissantia, Hyptis, Microtea, Mimosa caesalpiniifolia, M. misera, M. tenuiflora, P. moniliformis and Poaceae are very frequent in the analyzed honey, and characteristic of honey from Simplício Mendes. The absolute concentration analysis showed that 69% of the honey was classified in category I, 26% in category II and 5% in category III. A cluster analysis showed the formation of two major clades, one that shared many pollen types of Croton (S2) and another that shared the pollen types Borreria verticillata and Hyptis (S1). Two samples were considered monofloral honey (from M. caesalpiniifolia) and the remainder were considered heterofloral.