Alex da Silva de Freitas

Capacidade antioxidante da própolis

Propolis is a resinous substance collected by bees from many parts of plants and mixed with wax, pollen and salivary secretions. Its composition is complex and closely related to the vegetation features of each region. Thirty-three propolis samples were collected from four Brazilian regions (Northeast, Southeast, South and Central-West) and had their antioxidant activity analyzed by the connected oxidation of b -carotene/linoleic acid. A significant variation was observed for the antioxidant activity (51.33-92.70%), according to the region where the sample was collected. The antioxidant activity of propolis samples collected in the Northeast region was lower than those collected in the Central-West, South and Southeast regions, respectively.

A mid-Holocene vegetational and anthropogenic record in the Guanabara Bay region, Rio de Janeiro State, SE Brazil, assessed by palynological and charcoal data

Abstract Palynological and charcoal fragment analyses of Guanabara Bay sediments, as well as radiocarbon dating, were carried out on one 220 cm long sedimentary core collected from the northeast sector of the bay, near the São Gonçalo coast. This study aims at recognising and explaining the environmental history of this region during the mid-Holocene, and to identify the anthropogenic influences on it. The palynological data indicate the predominance of ombrophilous forest vegetation in the Guanabara Bay Hydrographic Basin at c. 6500 calendar years bp. During this period (pollen zone 1), the concentrations of pollen grains and spores may still have been controlled by the Holocene Maximum Transgressive Event. After a phase of low concentrations of palynomorphs, there was a considerable increase in the accumulation patterns of pollen and spore grains (pollen zone 2). This increase can probably be related to the retreat of the sea level event after the Holocene Maximum Transgressive Event. The 75 cm of the core top (pollen zone 3) provide clear evidence of human influence in the area, which is inferred from the significant reduction in ombrophilous forest pollen grains, the significant increase in herbaceous pollen grains, the presence of exotic pollen types (Eucalyptus and Pinus), and high concentration of carbonaceous particles.

The Holocene palaeoenvironmental evolution of Vitória Bay, Espírito Santo, Brazil

Abstract Micropalaeontological analyses of two sediment cores (T_A and T_D) collected from a tropical bay in Brazil were conducted. Continental palynomorphs and carbonised particle data were associated with stable isotopes (C and N) assessed using 14C dating. The main objective was to integrate these data with the results of isotopic analyses in order to establish the palaeoenvironmental dynamics of the area during the Holocene. The samples were sub-sampled every 10 cm and then submitted for standard methodological processing for each analysis. The T_A sediment core was dated at three depths, and the oldest depth, 150 cm, had an age between 7241–7339 cal yr BP. The T_D sediment core had an age between 6778 and6948 cal yr BP at its deepest depth, 370 cm. Using radiocarbon dating and micropalaeontological analyses, the integrated assessment of the two sediment cores indicated that the core with a coarser granulometry core was a continuation of the core with the finest granulometry. Consequently, both the lithological change and the preservation of the microfossils could be directly related to periods of sea level variations observed in the coastal region of Brazil.Micropalaeontological analyses of two sediment cores (T_A and T_D) collected from a tropical bay in Brazil were conducted. Continental palynomorphs and carbonised particle data were associated with...

Pollen Storage by Melipona quadrifasciata anthidioides in a Protected Urban Atlantic Forest Area of Rio de Janeiro, Brazil

Rio de Janeiro contains one of the largest urban forests in the world – a continuous covering of trees, shrubs, and lowland vegetation typical of the Atlantic Forest, with some exotic plant elements. Reforestation activities and conservationism require knowledge about pollination and seed production among native trees and shrubs adapted to local soil conditions. Besides other insects, birds, and bats, native Meliponini are significant pollinators that prefer certain plant species. The present study used pollen loads of Melipona quadrifasciata anthidioides, collected monthly from July 2014 to December 2015, in order to identify their floral resources and potential for pollination. Four localities were chosen to establish meliponaries inside the ombrophilous Atlantic Forest vegetation. Point 1 was established next to the Tijuca National Park visitor center, Point 2 in a lowland area of the Park, Point 3 inside a secondary and regenerating rainforest, and Point 4 inside a secondary and regenerating rainforest at a higher altitude. Pollen loads obtained from several bees each month were cleaned using ethanol, and 500 pollen grains identified. “Monofloral” was defined as >90% one floral species. Point 1 presented monofloral monthly pollen samples of Myrcia, Eucalyptus, Solanum, and Melastomataceae; Point 2 had Myrcia and Eucalyptus monofloral pollen, Point 3, Myrcia, Eucalyptus, Solanum, Anadenanthera colubrina, and Mimosa caesalpiniifolia, and Point 4, Myrcia, Eucalyptus, Anadenanthera colubrina and Melastomataceae. Bifloral batches were composed of two of these taxa. In conclusion, although Atlantic Forest is diverse, the native bee Melipona quadrifasciata anthidioides makes use of a few plant species only for its maintenance.

A melissopalynological analysis of Apis mellifera L. loads of dried bee pollen in the southern Brazilian macro-region

Abstract Sixty-one samples of dried bee pollen collected from various apiaries in the southern Brazilian macro-region were examined to detect the botanical origin of the pollen and to enable more accurate product certification. The palynological analysis of the samples followed the standard methodology and was conducted without the use of acetolysis. The samples were washed once or twice with ethanol and then with water. The sediment obtained was homogenised in a water/glycerine solution for microscopic observation. The target number of pollen grains to be counted was 500 pollen grains or more per sample. The results demonstrated that 35 samples consisted of a unique pollen type representing more than 90% of the pollen sum (or more than 60% if no accessory pollen was present). These samples were considered monofloral. Several pollen types grouped in a sample were related to heterofloral pollen batches. The most frequent pollen types were of Mimosa scabrella, Eucalyptus, Andira, Machaerium, Myrcia and Piptocarpha. The results of the current study were related to the surrounding vegetation of the apiaries and reflected the resources available to the bees. Furthermore, these results are relevant to apicultural activities and are commercially significant.