Early Floral Resources for Urban Bees From Ornamental Shrubs Ribes Aureum, Ribes Sanguineum and Staphylea Pinnata

This research aims to assess ornamental shrubs Ribes aureum, R. sanguineum and Staphylea pinnata as an early food source for urban bees. In a two-year study, the abundance and flowering pattern, nectar and pollen production, and spectrum of urban insect visitors were investigated in Lublin, SE Poland. The apiarian value of S. pinnata was studied for the first time. The studied species exhibited abundant and extended flowering, skewed inflorescence flowering pattern, and persistent flowers and inflorescences. They bloomed from late March to late May and could be considered as valuable early foraging resources for urban bees, despite the substantial differences between the species. The highest mean sugar yield and pollen yield · plant⁻¹ (92.9 g and 44.0 g, respectively) was estimated for S. pinnata whereas the lowest ones were found in R. sanguineum (4.3 g and 1.8 g, respectively). Hymenopterans were the principal flower visitors in the studied species accounting for more than 79% of all visits.