Evaluation of the expression stability of reference genes in Apis mellifera under pyrethroid treatment

Honeybees (Apis mellifera L.), which unquestionably play an economically important role in pollination and agricultural production, are at risk of decline. To study changes in gene expression in insects upon exposure to pesticides or other external stimuli, appropriate reference genes are required for data normalization. Since there is no such gene that is absolutely invariable under all experimental conditions, the aim of this study was to identify the most stable targets suitable for subsequent normalization in quantitative experiments based on real-time polymerase chain reaction in honeybee research. Here, we evaluated the expression of fifteen candidate housekeeping genes from three breeding lines of honeybees treated with pyrethroids to identify the most stable genes. The tested insects were exposed to deltamethrin or lambda-cyhalothrin, and then, changes in the accumulation of selected transcripts were assessed, followed by statistical analyses. We concluded that AmRPL32, AmACT and AmRPL13a were the commonly recorded most stable genes in honeybees treated with the selected pyrethroids.