Prevalence and distribution patterns of seven different honeybee viruses in diseased colonies: a case study from Croatia

The prevalence and regional distribution patterns of seven different honeybee viruses, i.e. Acute bee paralysis virus (ABPV), Sacbrood virus (SBV), Black queen cell virus (BQCV), Deformed wing virus (DWV), Kashmir bee virus (KBV), Chronic bee paralysis virus (CBPV), and Israeli acute paralysis virus (IAPV) were investigated using reverse transcription PCR (RT-PCR) analyses. Bee samples were collected in 82 apiaries located in 20 different districts of Croatia, mainly from bee colonies with various health problems. 9.75 % of investigated samples (apiaries) proved to be infected with CBPV, while ABPV, BQCV, SBV, and DWV were found in 10.97 %, 29.26 %, 40.24 %, and 95.12 % of apiaries, respectively. No samples tested positive for KBV and IAPV. Thus, the prevalences of BQCV, ABPV, SBV, and CBPV were generally lower in Croatia compared to other European Union member states, whereas the prevalence of DWV was similarly high. The possible reasons for these differences are discussed. This study provides the first molecular evidence for the presence of honeybee viruses in Croatian honeybees.