Abstract

The German cockroach,Blattella germanica, and the American cockroach,Periplaneta americanaare the most common and synanthropic household pests of interest to public health. While they have increasingly served as model systems in hemimetabolous insects for studying many biological issues, there is still a lack of stable reference gene evaluation for reliable quantitative real-time PCR (qPCR) outputs and functional genomics. Here, we evaluated the expression variation of common insect reference genes, including the historically usedactin, across various tissues and developmental stages, and also under experimental treatment conditions in these two species by using three individual algorithms (geNorm, BestKeeper, and NormFinder) and a comprehensive program (RefFinder).RPL32inB. germanicaandEF1α inP. americanashowed the overall lowest variation among all examined samples. Based on the stability rankings by RefFinder, the optimal but varied reference genes under specific conditions were selected for qPCR normalization. In addition, the combination ofRPL32andEF1α was recommended for all the tested tissues and stages inB. germanica, whereas the combination of multiple reference genes was unfavorable inP. americana. This study provides a condition-specific resource of reference gene selection for accurate gene expression profiling and facilitating functional genomics in these two important cockroaches.Keywords:cockroaches;reference genes;qPCR normalization;gene expression;functional genomics