Distribution and Quantification of Infectious and Parasitic Agents in Managed Honeybees in Central Italy, the Republic of Kosovo, and Albania

This study aimed to determine the presence of relevant infectious and parasitic agents (IPAs) in managed honeybees from Central Italy and the Republic of Kosovo and Albania to assess the overall health status of local apiaries by determining the contamination levels and co-occurrence. Therefore, pathogens and parasites such as Paenibacillus larvae, Melissococcus plutonius, Vairimorpha apis, V. ceranae, the acute bee paralysis virus (ABPV), black queen cell virus (BQCV), chronic bee paralysis virus (CBPV), deformed wing virus variants DWV-A and DWV-B, and the parasitoid flies Megaselia scalaris and Senotainia tricuspis were detected by quantitative polymerase chain reaction (qPCR) and reverse transcriptase qPCR (RT-qPCR) in clinically healthy adult honeybees collected from 187 apiaries in the Abruzzo and Molise regions of Central Italy, 206 apiaries in the Republic of Kosovo in 2022 and 2023 and 18 apiaries in Albania in 2022. The percentages of positive samples and contamination for V. ceranae, P. larvae and DWV-B were significantly higher in the Republic of Kosovo and Albania, while the percentages of samples positive for M. plutonius, CBPV, DWV-A, and the parasitoid flies were higher in Central Italy. Additionally, P. larvae and some viruses showed significantly different occurrence rates between the two years in Italy and the Republic of Kosovo. The co-occurrence of IPAs also differed between the two geographic areas. Their varying distribution could depend on epidemiological dynamics, climatic factors, and management practices specific to each country, whose relative impact should be defined to guide targeted interventions to reduce honeybee mortality.