## 4 Discussion  
In this study, we found a statistically significant difference in SHB presence between the area behind the MD and the remaining volume of the hive, highlighting the effectiveness of the MD method in concentrating SHBs behind the MD and optimizing the number of SHBs detected during hive inspections. These results can be attributed to the natural behavior of adult SHBs, which tend to escape from light [5]. As SHBs flee from light and beekeeper manipulation, they initially concentrate on the remaining frames before ultimately hiding behind the Mobile Divider device, which remains inside the hive. We should consider that the MD divider occupies a significantly smaller volume within the hive, suggesting that the actual difference in SHB abundance between the MD and other parts of the hive might be even greater. The absence of larvae during the inspection is consistent with other data on SHB infestation in Calabria, which are generally characterized by low infestation levels and the absence of larval stages [21]. Currently, the 'gold standard' diagnostic method for detecting the presence of SHBs in honey bee colonies, with 100% efficacy, remains the destruction of the infested colony, followed by visual inspection involving dissection of each frame [5]. However, this method cannot be applied systematically, as it is primarily intended for experimental purposes. As suggested by the Italian Ministry of Health, visual inspection of each frame is commonly used, but this method has proven to be time-consuming [20,22] in comparison to the MD method presented here. The efficacy of the MD method in concentrating SHBs behind the Mobile Divider can be compared to other diagnostic strategies, such as the use of corrugated plastic strips on the bottom board of each hive. In our study, the MD method showed an efficacy of 63%, detecting 63% of the total SHBs identified through full visual inspection of the colonies. This is higher than the approximately 30% efficacy reported for diagnostic strips [23,24]. Another study evaluated the efficacy of bottom board traps and reported an efficacy of 43.03 \(\pm\) 27.02% [25]. However, since that study compared trap-detected SHBs with those found through post-mortem colony dissection, direct comparison with the MD method is not applicable. During autumn 2022, the number of SHBs caught per inspection--conducted at three-week intervals--was higher than in late winter 2022 (Figure 3). However, even at the peak of SHB presence during the fourth inspection (1.8 SHBs/hive), the number of SHBs detected per hive remained low throughout both the seasons. Therefore, a three-week inspection frequency can be considered appropriate for both autumn and winter, ensuring that adult SHBs are effectively and promptly detected and removed. Our results regarding the efficacy of the MD method in concentrating SHBs, enhancing surveillance strategies, and supporting early detection are promising both in regions where SHB is already present and in regions where it has not yet been detected. This method may be particularly useful because, by concentrating SHBs behind the MD device, it allows for the detection of their presence in an apiary even when only a few adults are present and the infestation level is still very low. However, capturing and removing the detected SHBs presents some limitations, as there is no locking system to restrain them. As a result, while SHBs can be easily spotted, their removal and elimination depend on the beekeeper's skill in catching them. These findings were obtained in the Calabria region, where SHB infestation levels are low. Further studies should explore the factors influencing the MD method's efficacy and evaluate its performance in regions with higher SHB infestation levels. Conceptualization, G.F.; methodology, G.F., C.D.R. and F.A. ; software, A.D.S. ; validation, G.F. and A.D.S. ; formal analysis, A.D.S. ; investigation, C.D.R., A.D.C. and F.A. ; resources, F.A. ; data curation, C.D.R., A.D.C.