Table 1.
Experimental design.
Fig 1.
Relative abundance of the gut bacterial microbiota at genus level in non-infected and Vairimorpha ceranae-infected honey bees under different diet conditions.
The following treatments were applied: sugar syrup (C and CN), HiveAliveTM (HA and HAN), and 1.5% GanoBee (GB-3 and GBN-3). Honey bees of the treatment groups CN, HAN and GBN-3 were infected with V. ceranae. Samples for analysis were collected on days 0, 3, 6, 9 and 12 post-infection (pi). Genera with an abundance of less than 0.5% were grouped under ‘Other’. * Species identification by comparing the V3 - V4 regions of the 16S rRNA gene with reference sequences from GenBank database.
Fig 2.
Heatmap showing the relative proportions (%) of major genera identified in the gut bacterial microbiota of non-infected and Vairimorpha ceranae-infected honey bees under different diet conditions.
Honey bees were treated with sugar syrup (C and CN), HiveAliveTM (HA and HAN), and 1.5% GanoBee (GB-3 and GBN-3). Honey bees of the treatment groups CN, HAN, and GBN-3 were infected with V. ceranae on the 7th day post-emergence. Samples for analysis were taken on days 0, 3, 6, 9 and 12 post-infection (pi). * Species identification by comparing the V3 - V4 regions of the 16S rRNA gene with reference sequences from GenBank database.
Fig 3.
Alpha diversity (Shannon and Simpson indices) of the gut bacterial microbiota in non-infected and Vairimorpha ceranae-infected honey bees under different diet conditions.
Three diet conditions were applied starting from the emergence of honey bees: sugar syrup (C and CN), HiveAliveTM (HA and HAN), and 1.5% GanoBee (GB-3 and GBN-3). The treatment groups CN, HAN, and GBN-3 were infected with V. ceranae on the 7th day post-emergence. Shannon and Simpson diversity indices in a) non-infected and b) V. ceranae-infected honey bees on each sampling day. c) Box plots represent the mean diversity index value for each treatment group (n = 4-5).
Fig 4.
Non-metric Multidimensional Scaling (NMDS) plots illustrate beta diversity of the gut bacterial composition among honey bee treatment groups.
Honey bees were fed with sugar syrup (C and CN), HiveAliveTM (HA and HAN), and 1.5% GanoBee (GB-3 and GBN-3). The treatment groups CN, HAN, and GBN-3 were infected with Vairimorpha ceranae seven days after emergence. NMDS analysis was based on a) Bray-Curtis dissimilarity and b) Jaccard’s coefficient for binary data. Statistical differences were assessed with Permutational Multivariate Analysis of Variance (PERMANOVA). The ellipses show 95% confidence intervals per treatment group.
Fig 5.
Effects of applied diets and Vairimorpha ceranae infection on the relative immune gene expression in honey bees.
Graphs show relative gene expression (2−ΔΔCt) of abaecin (a-b), hymenoptaecin (c-d) and vitellogenin (e-f) (non-infected n = 3 and infected n = 5−7). Honey bees were sampled for analysis on days 0, 3, 6, 9 and 12 post-infection (pi). Three different diets were applied from the beginning of emergence: sugar syrup (C and CN), HiveAliveTM (HA and HAN) and 1.5% GanoBee (GB-3 and GBN-3). The treatment groups CN, HAN, and GBN-3 were infected with V. ceranae on the 7th day post-emergence. Different letters indicate statistically significant differences between treatment groups.
Fig 6.
Effects of different diets and Vairimorpha ceranae infection on the relative immune gene expression in honey bees within the same treatment group.
Graphs show relative gene expression (2−ΔΔCt) of abaecin (a-b) hymenoptaecin (c-d) vitellogenin (e-f) in honey bees (non-infected: n = 3 and infected: n = 5−7). Honey bees were sampled for analysis on days 0, 3, 6, 9 and 12 post-infection (pi). Three different diets were applied from the beginning of emergence: sugar syrup (C and CN), HiveAliveTM (HA and HAN) and 1.5% GanoBee (GB-3and GBN-3). The treatment groups CN, HAN and GBN-3 were infected with V. ceranae on the 7th day after emergence. Different letters indicate statistically significant differences between treatment groups.