## 3 Discussion  
In the case herein described sentinel honeybee colonies have been established to ease and improve the detection of SHB in the framework of the Italian national surveillance program applied in the infested areas of Calabria and Sicily regions. In each monitoring site, a pair of sentinel honeybee colonies are established under the supervision of the Veterinary Services of the Local Health Unit (National Health Service) and directly managed by official veterinarians. The advantages of relying on sentinels for SHB surveillance are as follows: inspection is less time consuming than a full-size colony, easily manageable by an official veterinarian, efficient in attracting and revealing the presence of SHB, cheaper (according to the Italian National Agriculture Bulletin the estimated cost is about 10,000 euro) than a full-size colony (they are killed and destroyed if found positive), and placed outside the apiaries so that Veterinary Services can freely access to them at any time. In addition, the competent authority can easily carry out the procedure of sanitary restriction, killing and packing under biosafety conditions when the sentinel is found infested by SHB. Additionally, disadvantages do exist, e.g., the sentinel does not always result as attractive to SHB as full colonies, SHB detection could depend also on the density of honey bee colonies in a certain area, specific training of official veterinarians is needed for both live inspection and hive management, the number of official veterinarians trained and  
Figure 8: Collected honeybees are screened for beetles with the help of a magnifying glass. Figure 7: Removal of the honeybees from the cells with a tweezer. available for the management of sentinels is not always adequate, sometimes the support of beekeepers is required. Sensitization of both veterinarians and beekeepers on the reliability of sentinel colonies for a SHB surveillance program is very important and can strongly improve the success of the intervention. The Sicily region could be taken as an example of this collaboration. In fact, they have been able to detect and eradicate SHB twice following incursions in 2014 and 2019. We are confident that a sentinel system is capable to detect SHB more easily than inspection of full colonies in apiaries and could efficiently contribute to the surveillance program that is fundamental to break down the progress of SHB in Italy. Of course, once established, the sentinel system requires to be maintained active for long periods, probably years. Furthermore, the development and implementation of this type of approach should be recommended to not yet infested areas that could be at risk of invasion. In addition to what was already mentioned, it should be clear that when designing a similar monitoring system, an appropriate knowledge of the territory is needed in terms of honeybee colony population, beekeepers and the beekeeping industry. Attention has also been devoted to managing SHB infested sentinel colonies in order to prevent any escape of beetles, i.e., sealing any opening of the hive, the quick and safe killing of the colony, biosecure packing with multiple layers of polyethylene film, adhesive tape, multiple plastic bags and transportation with no delay to the official laboratory or storage at \(-18\)\({}^{\circ}\)C until shipping. The use of multiple layers of polyethylene film was suggested also by [PERSON] et al. [20] to seal supers full of honey when transporting them from SHB non-infested, but at-risk areas, to extraction and processing facilities located in SHB non-infested areas. In conclusion, the procedures for packing and transport SHB infested sentinel honeybee colonies from the field to the official laboratory, and the subsequent protocol for their careful inspection in laboratory conditions are considered easy to apply, useful on a routine application and able to grant the required biosafety conditions. Conceptualization, [PERSON] ([PERSON]) and M.P.