Identification of reference genes for normalization of gene expression in Liposcelis entomophila (Psocoptera: Liposcelididae)

Abstract Liposcelis entomophila is a nuisance pest that seriously threatens the safety of stored grains owing in part of pesticide resistance. To facilitate better control of L. entomophila, future studies need to focus on gene function characterization. This requires the identification of suitable reference genes (RGs) for reverse-transcription quantitative PCR (RT-qPCR), which is crucial for the normalization of target gene expression. Here, we evaluated the expression stability of 12 candidate RGs in L. entomophila across six experimental conditions (developmental stage, population, body part, phosphine fumigation, hypoxia induction, and temperature treatment). Under developmental conditions, ACTB, HSP70, and RPL23 were the most stable RGs. Among the different populations and body parts, RPL23, EF1a, and ACTB were the most stable RGs. Comparison of gene expression among adults under different environmental conditions revealed that at least seven RGs were fit for normalizing gene expression data. Among them, RPL23, EF1a, and ACTB showed the best fit as RGs in RT-qPCR analysis. After validation, our results demonstrated that EF1a and ACTB, as well as their combination, were the ideal RGs for L. entomophila across various experimental conditions. This study provides a comprehensive RG selection suggestion for gene expression studies of L. entomophila and will facilitate future functional genomic research on the development and tolerance of environmental factors in psocids.