Environmental and Colony-Related Factors Linked to Small Hive Beetle ( Aethina tumida ) Infestation in Apis mellifera

The small hive beetle (SHB) was first detected in Italy in 2014 and remains confined to the regions of Calabria and Sicily (Italy). The environmental and colony-related factors favorable to the development of SHBs are widely studied, but mainly at the laboratory level; it is not yet clear whether these factors also apply in the field within apiaries in regions affected by SHBs. In 2022, we conducted a study in the province of Reggio Calabria, Italy, to investigate if these factors influence SHB infestation levels in honey bee colonies. Data were collected from 67 hives in late winter and 81 hives in autumn, inspecting each hive three times per season. Overall, SHB infestation levels were low (an average 0.83 SHB/hive). Our analysis revealed a significant relationship between the SHB infestation level and the following six factors: the number of combs covered by adult bees, the total number of combs, combs surveillance, the previous month’s infestation, sun exposure, and season. GLM analysis predicted a higher number of SHBs in colonies with fewer combs covered by adult bees (2.543), with a greater number of combs (1.877), with lower comb surveillance (0.935), with a higher SHB infestation level in the previous month (1.192), in shaded locations compared to sunny ones (0.207), and in autumn compared to late winter (0.258), with peak infestations in September. These findings provide insights to inform surveillance plans, optimise sentinel apiaries setup in SHB-free regions, and offer practical guidance for beekeepers on implementing biosecurity measures to minimise infestation levels and enhance early detection. Future research should examine whether these factors have similar effects in regions with higher SHB infestation rates.