## 4 Discussion  
Monitoring the bee and plant taxa over two years yielded significant insights into the composition and interactions between the pollinators and plants in the monitored urban areas of Milan. Regarding the bee taxa, the highest percentage of observations was consistently represented by _A. mellifera_ and the _Anthidium_ spp., which dominated interactions across both years. The restrictions imposed by the COVID-19 pandemic in 2020 impeded the implementation of a comprehensive monitoring program, resulting in a slight alteration in the composition of the bee community between the two years. This shift can be predominantly attributed to an increased prevalence of the _Osmia_ spp. in 2021, particularly _O. cornuta_ and _O. bicornis_, which typically emerge during the spring months, precisely those heavily impacted by the COVID-19 restrictions in 2020. Figure 8: Microphotograph observed by negative staining immune electron microscopy (IEM): (**A**) DWV (Deformed Wing Virus) in _A. mellifera_. (**B**) for ABPV (Acute Bee Paralysis Virus) in _B. terrestris_. (**C**) for ABPV (Acute Bee Paralysis Virus) in _A. mellifera_. Negative staining, NaPT 2%. The network analysis further highlighted the complexity of the plant-pollinator interactions in the urban context, as stated in previous research [76; 77]. The number of pollinator taxa changed over the two years but not among the urban greenery areas. In contrast, the number of plant taxa varied between the small area (the roundabout) and the other categories. The same trend was found for the Shannon diversity index and modularity, which were lower in the green street spaces than in the historic parks. The result showed that the number of pollinator taxa did not change among the greenery areas, suggesting that, even with its low number of plant taxa, a small area was still an important landscape feature for pollinators [76; 78]. Notably, our results showed many interactions concentrated on a few floral taxa, suggesting that multiple pollinator species often converged on shared plant resources. Despite the high diversity of bee species and interactions observed in most of the urban green spaces, competition between the species always seemed intense. As in the other studies [79; 80], the competition network analysis in the present work revealed that, while many species contributed to pollination in these environments, only a few demonstrated strong competitive potential within each park. These species, dominating by the number of interactions, could monopolize access to floral resources and reduce the opportunities for less competitive species. This suggests that, while parks may support a broad range of pollinators, the dynamics of competition among them can result in the dominance of a few key species, with implications for the overall health and stability of pollinator communities. Among the bee taxa, _A. mellifera_ stood out as the species with the highest number of interactions across a wide range of plant taxa. Our results confirm the great intraspecific competition of _A. mellifera_, as reported in [74], with pathogen transmission between and within species. This finding is particularly significant because honeybees, which are known to transmit pathogens to wild pollinator species, play a dominant role in these interactions. This underscores their potential impact on the health and stability of wild pollinator communities, emphasizing the need to manage their interactions across diverse ecological settings. Our focus on dominant species was dictated by the following two important facts: these species are expected to have the highest number of interactions and, consequently, they may be more susceptible to pathogen spillover events. This was confirmed by the consistent positive detections throughout the monitoring period. Furthermore, the collection of _Osmia_ bees in the second year provided evidence that spillover events can also occur early in the season for given pathogens. The collection of the exotic bee _M.