HSP70 expression of Folsomia candida in the temperature treatment normalized with four different sets of reference genes. HSP70 expression between different pools of F. candida exposed to different temperatures, normalized with four different sets of reference genes (ACTb: only beta-actin; the best set selected by geNorm (SDHA &ETIF); the best set selected by Normfinder (ETIF, SDHA, EF1a &UBC) and all available reference genes). One-way ANOVA analysis with Bonferroni post-hoc test revealed significant differences (P < 0.05) between 0, 10 and 20°C and between 10, 20 and 30°C in all normalization sets. Significant differences between 0 and 30°C were only detected when normalized with the optimum sets of reference genes selected by either geNorm or Normfinder. The letters above the bars indicate significant differences where different letters between bars represent a significant difference within 1 normalization set.