The resumption of activity in spring is an important moment for the development of the bee colony and it is influenced by both the interventions carried out by beekeepers in the previous autumn and winter seasons and the pathogens occurrence in the hives. To date most pathogens and parasites affecting honey bees have an almost worldwide distribution [5; 6], and they include viruses, fungi, bacteria, protozoa and parasitic mites which, alone or in association [7; 8], or as a result of particular environmental or hive conditions, could affect the health of the apiaries. It is well known that both _Nosema_ spp. (_Nosema apis_ and _Nosema ceranae_) and several viruses are a major cause of honey bee diseases. _Nosema_ spp. can affect the productivity and survival of honey bees altering their longevity and behaviour, brood rearing and pollen collection [9; 10]. It was also reported that co-infection by virus and _N. ceranae_ in honey bees might be associated with colony collapse disorder (CCD) [11]. Currently, more than 30 viruses have been identified in honey bee populations [6] and multiple viral infections have been reported in bees [12; 13; 14; 15; 16; 17]. Six of these viruses can be responsible for severe diseases in honey bees: acute bee paralysis virus (ABPV), black queen cell virus (BQCV), chronic bee paralysis virus (CBPV), deformed wing virus (DWV), Israeli acute paralysis virus (IAPV), Kashmir bee virus (KBV), and sac-brood virus (SBV). These pathogens can attack different developmental stages of the honey bees including eggs, larvae, pupae, adult worker, drones and queens. Their transmission can occur both horizontally between bees and vertically from queen to offspring. ABPV, KBV and IAPV are closely related dicistroviruses [18; 19] that normally persist at a low level of infection within the colony, with no obvious symptoms at the individual or colony level. However, they are extremely virulent when injected into pupae or adults [20]. Considering these features upon injection into the bee haemolymph, it is not surprising that they are usually related to _V. destructor_, which, when feeding on the bee's haemolymph, can transfer ABPV among the colony, causing paralysis of adult bees and death in a short time. While ABPV and IAPV have been reported to result in rapidly progressing paralysis and death of honey bees [21; 22], KBV affects both brood and adult bees with no visually detectable clinical symptoms and can be spread between bees and from the queen to her offspring [23]. BQCV is one of the most prevalent and widespread viruses in honey bee colonies, with a constant annual incidence in the adult population. Although BQCV does not cause visible symptoms in infected adult bees, it can kill queen larvae and pupae by turning their cells black [24]. BQCV has been related with _Nosema_ spp. infestation and other viruses [25], but it is still unclear how they are linked. CBPV is an unclassified bipartite RNA virus [26] with a worldwide distribution, above all in Asia, Europe and North America [27; 28; 29], causing a rare but severe chronic paralysis. Infected honey bees show abnormal trembling, making them unable to fly, and darker, hairless abdomens [30]. Symptomatic individuals seems to be too weakened for pollination or honey production and often die in few days [21; 31], leading to mounds of dead bees outside affected colonies, which sometimes collapse. SBV and DWV are single-stranded positive-sense RNA virus members of the Iflavirus genus [30; 32; 33]. SBV was the first virus identified in honey bees and is transmitted to larvae by SBV-infected nurse bees [34], leading the larvae to fail to pupate [35; 36], acquire a sac-like appearance and finally die. SBV can also affect adult bees without clinical signs of disease, even if such bees may have a shorter life span [37; 38]. The virus may remain viable in dead larvae, honey, or pollen for weeks, so the infection can be further spread from one hive to another through swarming and drifting of the virus-infected colonies.