## 4 Discussion
mellifera_ in 2021 but also associated with _An. florentinum_ and _B. terrestris_ in 2020. The virus was documented in at least seven wild bee genera, including stingless bees [90], bumblebees [23; 91], members of the Halictidae family, and hornets [42; 90; 92]. The presence of the virus was already known in northern Italy for several species of wild pollinators [93]. In bumblebees, wing deformities can be determined by this virus [23], which can also reduce the survival of bumblebees artificially inoculated with DWV [18]. Deformities were also observed in some of the bumblebees collected in this study. Active replication has also been confirmed in both the _Osmia_ and _Melipona_ species [25; 94]. However, despite the possibility of active replication, it appeared to be less widespread among the wild bees than the honeybees. BQCV was detected only in 2020 and in association with _A. mellifera_, _B. pascuorum_, and _An. florentinum_. The virus was found to be prevalent in honeybees but not associated with transmission by varroa mites. It had already been detected in association with bumblebee species by colleagues [42; 93; 95], and BQCV has been known to efficiently replicate in different bumble bee species [96; 97]. Due to the analytical method used (qualitative PCR), however, we do not have the corresponding viral load. Furthermore, even if it was widespread in the wild bumblebee populations, the foragers largely harbor low levels of such viruses [85]. CBPV was detected in _A. mellifera_ during both years, as well as in _B. terrestris_ and the _Anthidium_ spp. in 2020, albeit always at low titers. CBPV is a non-classified RNA neurotrophic virus. It was first isolated in 1963 from bees showing neurological symptoms of paralysis, such as the incapacity to fly, ataxia, and trembling [98]. The distribution of CBPV is widespread in _A. mellifera_ populations on a global scale [99]. Its presence has also been documented in _A. cerana_[100], _B. terrestris_[101], and _B. impatients_[89]. Furthermore, CBPV infects ants (_Formica rufa L., Camponotus vagus_ Scopoli) and _V. destructor_[102], with ants representing a virus reservoir and the mite serving as a virus vector facilitating the spread of CBPV in the honeybee population. Finally, compared with only one in 2020, eight SBV-positive samples were found in 2021 in different pollinators, namely _An. florentinum, M. sculpturalis_, and _B. terrestris_. SBV is one of the widespread viruses in the world in _A. mellifera_ and _A. cerana_, and it is the etiological agent of the sackrood disease in a bee brood. SBV is a common virus and, although sackrood disease is lethal for infected larvae, colonies that show symptoms of sackrood rarely collapse. Hence, SBV poses a moderate threat to managed honeybees. SBV has also been detected in varroa mites [103; 104] but without replication. Unlike the other honeybee viruses, SBV seems to have a narrow range. It has been found in several _Bombus_ species [42; 85; 91; 105] and in the solitary bee _Andrena vaga_ [PERSON], 1799 [106], but it does not seem to replicate in these hosts. Therefore, its host range may be more limited and may not pose the same level of threat to wild pollinators as the viruses capable of replication. By electron microscopy, additional picornavirus-like particles were observed in small quantities in the samples from the diverse pollinators. These particles were identified as isolated, scattered entities. In some cases, they could refer to the particles detected by PCR, notably ABPV and DWV. However, in at least one case in 2021, a viral positivity for picornavirus-like was detected in a mason bee, which was found to be negative by molecular methods. This potentially represents a different unidentified viral agent. The application of next-generation sequencing methods, which have recently been introduced for bee virus detection studies, leading to the identification of new agents or variants of the existing ones (reviewed by [84]) will undoubtedly allow us to better characterize new viruses in the future.