Varroa Mite and Viral Prevalence in Honey Bees

All statistical analyses and data visualizations were performed in GraphPad Prism 7.0 (GraphPad, La Jolla, San Diego, CA, USA). Normality of data was assessed by use of the Kolmogorov–Smirnov test and homogeneity of variance was determined with Levene’s test. The results were expressed as the number of varroa per 100 bees or the presence or absence of varroa mites, as well as viral presence/absence in each apiary per season. Chi-square tests were used to test for differences in proportions (varroa mite presence/absence; viral prevalence/absence in winter versus summer). The association between viral presence (yes/no) and varroa infestation (number of varroa per 100 bees) were compared using Student’s t-tests with Welch’s correction for unequal variances and Bonferroni correction for multiple testing (12 tests, representing the occurrence of a virus in the winter or the summer). An adjusted alpha level of 0.05 was used for all statistical tests to define significance.