Search

The conception of “floral strips” is a strategy to provide more and different food sources for pollinators. The impact of “homogeneous” Phacelia tanacetifolia (“Phacelia”) and “heterogeneous” (flower mix) food sources on the enzyme activity of bumblebees (Bombus terrestris) and honeybees (Apis mellifera) under urban conditions has not been reported. Organisms responding to challenging environmental conditions are known to exhibit increases in oxidative stress parameters which in turn affect both physiological and metabolic parameters. A field study was conducted in Berlin-Dahlem, Germany, using the response of the “marker” enzyme superoxide dismutase (SOD) on food sources for assessment. SOD data is also shown from the wild bee Megachile rotundata (Fabricius 1787), obtained from three different locations in the federal state Brandenburg, Germany. The results demonstrate that the enzyme activity of SOD significantly increased in bumblebees visiting the flower mix compared to the Phacelia. The experimental approach had individual effects at the level of the species, bumblebees and honeybees, respectively. The activity of the biomarker SOD could be successfully used to assess the effects of the compositions of homogeneous and heterogeneous flower fields. “Advancement of women” of the Albrecht Daniel Thaer-Institute (ADTI), Faculty of Life Sciences, Humboldt-University of Berlin

Many biochemical processes are involved in regulating the consecutive transition of different phases of dormancy in sweet cherry buds. An evaluation based on a metabolic approach has, as yet, only been partly addressed. The aim of this work, therefore, was to determine which plant metabolites could serve as biomarkers for the different transitions in sweet cherry buds. The focus here was on those metabolites involved in oxidation-reduction processes during bud dormancy, as determined by targeted and untargeted mass spectrometry-based methods. The metabolites addressed included phenolic compounds, ascorbate/dehydroascorbate, reducing sugars, carotenoids and chlorophylls. The results demonstrate that the content of phenolic compounds decrease until the end of endodormancy. After a long period of constancy until the end of ecodormancy, a final phase of further decrease followed up to the phenophase open cluster. The main phenolic compounds were caffeoylquinic acids, coumaroylquinic acids and catechins, as well as quercetin and kaempferol derivatives. The data also support the protective role of ascorbate and glutathione in the para- and endodormancy phases. Consistent trends in the content of reducing sugars can be elucidated for the different phenophases of dormancy, too. The untargeted approach with principle component analysis (PCA) clearly differentiates the different timings of dormancy giving further valuable information.