An attempt to promote ground-nesting bees in an urban landscape. Investigating the use of sand beds as a conservation effort.

Abstract: Pollinators provide crucial services for the ecosystems by pollinating around 80-90% of all plants. However, pollinating insects are declining worldwide which may cause a parallel decline in plant species leading to large biodiversity losses. One major cause for pollinator declines is habitat destruction which has large implications for ground-nesting bees. This nesting strategy is used by 64-83% of all known bee species. Rapid urbanization is diminishing the bees nesting habitat. To mitigate this problem, the present study aimed to investigate if the addition of sand beds in Slottsskogen, a city park located in Gothenburg, Sweden, could attract ground-nesting bees and serve as a conservation effort. For the analysis, seven sand beds were investigated, each paired up with two controls. Bees and other Hymenopterans were caught during late May-August 2023 through netting for 15 min for each area. In addition, floral inventories were made in a 200- meter buffer zone around the sand beds to examine if important plant species for bees occurred in the area. A generalized linear mixed model and an ANOVA was performed on two different datasets: 1) bees 2) bees + other hymenopterans (total). The results showed no significant effect between sand beds and controls for 1) bees. For 2) bees + other hymenopterans (total), the results showed a significant effect where more insects were caught on the sand beds compared to the controls. The floral inventory found important plant species in the proximity of the sand beds. Not finding many bees in the sand beds can be due to the sand not meeting the proper requirements the bees need. There is a big knowledge gap in the research field of ground-nesting bees and future studies would benefit from including examination on different soil properties and slopes to investigate if alterations in the Slottsskogen sand beds needs to be done to attract more bees.