Honeybee immune genes showing significant differences (P≤0.05) of their transcription level, as affected by different mite infestation densities.

The gene expression values, as Reads Per Kilobase of exon model per Million mapped reads (RPKM) [84], scored on bees from low infested and highly infested colonies are reported. The “fold change” represents the ratio between the average gene expression value of highly infested colonies and that of low infested ones; values smaller than one indicate a significant transcriptional down-regulation, while those higher than 1 indicate up-regulation. An asterisk marks genes whose differential expression was confirmed by Quantitative Real-Time RT-PCR (Figures S2 and S3). A significant down-regulation of several immune genes was observed in bees from highly infested colonies; the most marked effect was recorded for dorsal-1A, a member of the NF-κB gene family.