Prevalence of bee viruses among Apis cerana populations in Vietnam

Abstract

We studied the prevalence and distribution of seven honey bee viruses, namely: acute bee paralysis virus (ABPV); cloudy wing virus (CWV); Israeli acute paralysis virus (IAPV); Kashmir bee virus (KBV); sacbrood virus (SBV); black queen cell virus (BQCV); and deformed wing virus (DWV), in healthy colonies from ten provinces in Vietnam. Colonies from each apiary were randomly selected to check viral infection. To confirm virus infection, samples were tested by Reverse Transcription Polymerase Chain Reaction using specific primer pairs. The positive products were sequenced and compared with the reference sequences using Basic Local Alignment Search Tool for molecular confirmation. In 360 Apis cerana samples, we found that the most prevalent virus was SBV (in 18.33% of samples), followed by BQCV (6.11%) and DWV (3.33%). The other four viruses, ABPV, CWV, IAPV, and KBV, were not detected in any sample. Infection rates were higher in adult bees than in larvae. The prevalences of SBV, BQCV, and DWV were 25.00, 10.56, and 6.11% in adult bees, and 11.67, 1.11, and 0.56% in larvae, respectively. The occurrence of BQCV and DWV varied across geographic regions. BQCV occurred mainly in the northern provinces, while DWV was predominant in the southern provinces. SBV, however, was found in all sampled provinces and exhibited similar infection rates. In adult bees, co-infection rates of BQCV with SBV or DWV were 2.22 and 0.60%, respectively.