Fig 1.
The effects of T. mercedesae infestation on flight ability of adult honey bee (n = 45).
A: flight distance; B: flight duration; C: mean flight velocity. CK: non-infested honey bees; T: T. mercedesae-infested honey bees. Horizontally, the width of each violin box represents the density of the data values. The white dots represent the median values of each group. The upper and lower edges of the black thick line represent the 3/4 digits and 1/4 digits of the data. The upper and lower ends of the thin line represent the maximum and minimum values of non-outliers of the data.
Fig 2.
The effect of T. mercedesae infestation on homing ability of adult honey bee.
Violin plot shows the homing time in control bees and T. mercedesae infested bees (n = 56–96). Horizontally, the width of each violin box represents the density of the data values. The white dots represent the median values of each group. The upper and lower edges of the black thick line represent the 3/4 digits and 1/4 digits of the data. The upper and lower ends of the thin line represent the maximum and minimum values of non-outliers of the data. CK: non-infested honey bees; T: T. mercedesae-infested honey bees.
Fig 3.
The effect of T. mercedesae infestation on olfactory associated functions of adult honeybee.
A. The effect of T. mercedesae infestation on sucrose responsiveness of adult honeybee. Infested and control bees were tested for PER to 30% (w/w) sucrose solutions at 0, 5, 10 and 15 days after emergence. PER rate (%) was significantly lower in infested bees at day 15 than that of control group. 0 day indicates newly emerged adult bees. B. PER responses of infested or non-infested honeybees during the conditioning phase (C1–C3). C. PER responses of infested or non-infested honeybees during the extinction phase (T1–T5). CK: non-infested honey bees; T: T. mercedesae-infested honey bees. Data are means of three independent experiments, and error bars represent ± standard error (SE). Significant differences to CK with P < 0.01 are indicated by asterisks according to chi-squared test.
Fig 4.
Schematic of RNA-seq experimental design.
The experimental design consisted of three groups displaying different sucrose responsiveness or learning ability.
Fig 5.
The differentially expressed genes (DEGs) between healthy bees and infested bees.
A. The Venn diagram of differentially expressed genes between bees with and without olfactory learning ability in both the T. mercedesae-treated group and the CK group. B. the number of DEGs in each comparison. Up-regulated and down-regulated means that these genes were higher or lower expressed in infested group compared to CK group. C. COG Function Classification of DEGs in comparision CKL/TL.
Fig 6.
The differentially expressed genes (DEGs) between bees with or without learning ability in CK group and T. mercedesae-treated group.
A&B, GO term enrichment analysis in CKSN/CKL and TSN/TL was performed. The first lap indicates top 20 GO term and the number of the genes corresponds to the outer lap. The second lap indicates the number of the genes in the genome background and Q values for enrichment of the DEGs for the specified biological process. The third lap indicates the ratio of the upregulated genes (deep purple) and downregulated genes (light purple). The fourth lap indicates the enrichment factor of each GO term. C. Heatmap of related transcripts identified in the comparison between bees with or without learning ability. D. Heatmap of chemosensory-related transcripts identified in the comparison between bees with or without learning ability. The colours indicate the log2-transformed expression values, which represent the expression level of a transcript identified in control group or infested group.
Fig 7.
Flagellum of the honey bee antenna observed with scanning electron microscopy (SEM).
A. SEM of antennal segments of scape for worker showing antenna and olfactory sensillum B. The number of sensilla placodea on 4, 7, 8 segments in the right antennae of infested and non-infested bees at 0, 5, 10 and 15 days. C. The size of sensilla placodea in the right antennae of infested and non-infested bees 0, 5, 10 and 15 days. For the actual measurement was performed in duplicate (i.e. two biological replicates, A and B) alongside controls.
Fig 8.
The effect of T. mercedesae infestation on mushroom body in the brain of adult honey bees.
A. Photomicrographs of sections of mushroom body of control worker bees and T. mercedesae infested bees stained with hematoxylin and eosin. The black circle was indicated mushroom body of individual honeybee. B. The thickness of mushroom bodies of control bees and T. mercedesae infested bees. Data are means of three biological replicates, and error bars represent ± standard error (SE) (n = 3). Significant differences to CK with P < 0.05 are indicated by an asterisk above the bars and were determined by one-way ANOVA followed by Tukey’s HSD.