## 4 Discussion  
In recent years, numerous events of honey bee mortality or beehive depopulation have been reported in Europe and other countries around the world. Several causes have been identified as responsible stressors, in particular, the presence of different pathogens and parasites that can act individually or in synergy. During the last years, monitoring plans have, therefore, been set up at national level to know the health status of bee colonies and, in Italy, the ApeNet (2009-2010) and BeeNet (2011-2014) projects and other studies were established to monitor hundreds of apaires distributed over almost the entire Italian territory in order to assess the health of _A. mellifera_(28; 72; 73). The resumption of activity in spring is an important moment for the development of the bee colony and is influenced by both the interventions carried out by beekeepers in the previous autumn and winter seasons and the pathogens presence in the hives. In order to collect information on the health status of nine apaires situated in the Veneto region, in northeast of Italy, we investigated in spring the presence, distribution and prevalence of eight viruses (ABPV, CBPV, DWV-A, DWV-B, SBV, BQCV, IAPV and KBV), fungi (_Nosema_ spp. ), trypanosomatids (_L. passim_ and _C. mellificae_) and _Varroa_ mite. A total of ten pathogens (_N. ceranae_, _L. passim_, _C. mellificae_, ABPV, CBPV, BQCV, SBV, DWV-A, DWV-B, _V. destructor_) were found in spring 2020 and 2021, even if all the honey bees analysed for each year showed no clinical symptoms of disease. BQCV and SBV were the most prevalent pathogens over the two years in all the apiaries investigated (Figure 2). This not only confirm what has already been shown in studies previously conducted in many European countries as Italy [28], Austria [74], Belgium [75; 76], Germany [1], Spain [58], Denmark [77] and France [78], but the infection levels of these viruses in Veneto was higher than the level reported in the literature. SBV is the most widely distributed of all honey bee viruses [36]. As reported by [PERSON] et al. [79], high prevalence of SBV is frequent in European honey be colonies, particularly in spring and summer, when the colony is growing most rapidly and large numbers of larvae are available [78], and it is generally higher both in symptomatic and asymptomatic honey bees [80]. The BQCV infection mainly affects queen larvae and pupae instead and has the highest incidence in spring and early summer; BQCV infected adult bees normally do not exhibit outward disease symptoms [78]. Moreover, several previous reports linked BQCV disease outbreaks with infection of _N. apis_(74; 78; 81) and _N. ceranae_(25; 82; 83; 84; 85), suggesting that these pathogens can act synergistically. Even if many apiaries analysed in this study showed co-infections of BQCV with _N. ceranae_, no statistically significant association was found, since BQCV infection was always present in almost all the hives. As already mentioned above, _N. ceranae_ spores were detected, even in considerable number, in several honey bee colonies while _N. apis_ was never found. The overall prevalence values of _N. ceranae_, 71.3% in 2020 and 64.4% in 2021, respectively, confirmed the higher diffusion of _N. ceranae_ previously reported in different Italian regions [86; 87; 88], in other European countries [53; 58; 89; 90] and worldwide [51; 63; 91; 92; 93]. The high prevalence of _N. ceranae_ together with the absence of _N. apis_ infection corroborates the findings of other authors that _N. ceranae_ is definitely spread in Italy and has basically replaced _N. apis_(86). The hives of apiary A were the only colonies with the lower levels of _N. ceranae_ infection, but while in 2020 only one hive has been analysed, since the beekeeper was unable to sample a sufficient number of bees, in 2021 only 10% of the hives were positive to _N. ceranae_. All the hives of apiary C tested negative to _N. ceranae_ in 2020, whereas in 2021 all of them were positive.