ABSTRACT. The stingless bee Tetragonisca angustula is an important pollinator of different agricultural and native crops. This study evaluated changes in the relative activity of esterases and critical electrolyte concentration in brain cells after exposure to pesticides malathion and thiamethoxam. Lethal concentration 50% showed greater toxicity of thiamethoxam in relation to malathion. Esterases EST-3 and EST-4 (carboxylesterase) were partially inhibited after contamination by contact and ingestion of malathion and contamination by contact with thiamethoxam, suggesting participation of these esterases in the metabolization of these compounds. The lowest critical electrolyte concentration (CEC) was found after contamination by malathion ingestion (0.15 M), indicating changes in gene expression. The alterations observed in the intensity of EST-3 and EST-4 and the chromatin structure indicate that pesticides can act in gene expression and be used as biomarkers of contaminant residues. Furthermore, knowing the susceptibility of T. angustula bees to pesticides, it would be possible to use this species for biomonitoring environmental quality in preserved areas and agroecosystems.

ABSTRACT The potential of royal jelly production in Africanized honeybee colonies was evaluated using techniques involving two queens per colony in horizontal and vertical systems during the spring of 2019. The techniques were tested for their effect on cell acceptance (%); royal jelly production per colony (g), per harvest (g), and per position of cell bar (g) and compared with standard techniques (five and ten-frame hives) in southern Brazil. Results showed statistical significance in royal jelly production between methods. Vertical colonies produced a significantly greater amount of royal jelly per colony and per harvest (8.26 and 53.28±4.98 g) compared with single-queen colonies in ten-frame hives (4.30 and 32.76±3.57 g) and five-frame hives overlapping (2.03 and 14.45±2.48 g), but did not differ from two-queen horizontal colonies (8.09 and 46.81±4.90 g). In contrast, there was no significant difference in queen cell acceptance rate within vertical, horizontal, and ten-frame colonies. Royal jelly yield of two-queen vertical colonies increase as compared with standard colonies.

Abstract The Southern region of Brazil is known for its floral diversity, presenting great potential for bee products such as honey, pollen, propolis and royal jelly. In this study, 67 honey samples provided by beekeepers from 14 municipalities of western Paraná were evaluated. Physicochemical parameters, bioactive compounds and antioxidant activity were analyzed. The physicochemical parameters of the samples were in compliance with the specifications by national and international standards, presenting average values of 3.26, 34.54 meq.kg-1, 18.75%, 10.79 mg.kg-1, 0.14% and 340.10 µS.cm-1, for pH, acidity, moisture, hydroxymethylfurfural, ash content and electrical conductivity, respectively. The nutritive values of honey, on average, achieved 0.28% of protein from 69.09% of total sugars, 64.57% of reducing sugars and 4.28% of sucrose. Bioactive compounds showed average values of 34.83 mg GAE/100 g-1 of total phenols and 16.26 mg EQ/100 g-1 of flavonoids, enabling antioxidant activity of 2.68 µmol FE (II)/g-1 of FRAP, 1.01 µmol ET/g-1 from ABTS and 0.12 µmol ET/g-1 of DPPH. This first study evaluated the parameters through cluster analysis and observed nine groups formed, as well as the characteristics between the samples with similar reaction. We concluded that the honey samples have high similarity and confirmed the quality of the honey produced.

Abstract Antimicrobial activity of honey has lately drawn researchers’ attention, especially due to the fact that its antimicrobial capacity has been proven. The aim of this study was analyzing bactericidal and bacteriostatic action in the pathogenic microorganisms Staphylococcus aureus, Escherichia coli and Candida albicans of honey samples from five regions of the state of Paraná. Candida albicans yeast showed to be more resistant to honey than the bacteria Escherichia coli and Staphylococcus aureus. The minimal inhibitory concentration found for the three microorganisms tested was 12.5% to 25%. The minimal bactericidal concentration, in its turn, was 25% for bacteria and 25% to 50% for yeast. The samples from the Southern area had the best results for both the minimal inhibitory and the bactericidal concentrations. Through physicochemical and phyto-chemical analysis, we observed that several factors are associated to the bactericidal capacity of honey. In conclusion, honey is an excellent bactericidal agent with a great biotechnological potential. Its properties are directly related to its geographic origin, which gives each type of honey its own characteristics.