Seasonal dynamics of Apis mellifera filamentous virus (AmFV), Black queen cell virus (BQCV), Chronic bee paralysis virus (CBPV) and Deformed wing virus (DWV) in Apis mellifera colonies infested by Varroa destructor

BRASESCO, CONSTANZA ; QUINTANA, SILVINA; SZAWARSKI, NICOLÁS; RAMOS, FACUNDO; FERNANDEZ DE LANDA, GREGORIO ; IGLESIAS, AZUCENA; MITTON, GIULIA ; EGUARAS, MARTÍN; MAGGI, MATÍAS

Congreso; XXI Reunión Anual de la Sociedad Argentina de Biología; 2019

Current studies in Apis mellifera colonies of Argentina have reported the presence of the most relevant +ssRNA viruses of bees, such as DWV, BQCV and CBPV; and of the filamentous virus of dsDNA AmFV. Even so, studies that evaluate the role of the ectoparasitic mite Varroa destructor in the seasonal dynamics of these viruses in Argentina are scarce, hence the objective of the present study. Approximately 50 workers were sampled from 4 hives each, naturally infested by the mite, from the experimental apiary of Finca Santa Paula; and were stored at -80 °C. Sampling was done once for each of the seasons of the year, from autumn 2016 to summer 2016-2017. Total RNA and DNA were extracted from pools of 10 worker bees, randomly selected from each sample. DNA was isolated using Roche Diagnostics DNA extraction kit and then qPCR reactions were performed for AmFV detection. RNA was extracted using Trizol® reagent, digested with DNAse and then RT-qPCR reactions were performed for DWV, BQCV and CBPV detection. Bee?s β-actin qPCR was performed as an internal control to check the quality of the material from each sample, and to calculate the relative expression (ER) of each virus using the equation 2-ΔΔCt. Statistical analyzes of the variables affecting the ER of each virus were carried out through the R statistical program using generalized linear mixed models (GLMM). Detections were positive in all samples except for CBPV from two samples of autumn. The seasonal dynamics of the 4 viruses analyzed coincided with the historical data records for these viruses in various parts of the world. The ER of the DWV was found to be significantly higher in autumn, consequently leading colonies to a greater vulnerability to Varroa and other pathogens, and to death in the short term. Future studies on a larger scale are necessary to elucidate the existing correlations between the seasonal dynamics of the A. mellifera/V. destructor parasitic system and these associated viruses.