Selection and Validation of Reference Genes for Quantitative Real-Time PCR Analysis in Cockroach Parasitoid Tetrastichus hagenowii (Ratzeburg)

Abstract

Parasitoid wasps play a crucial role in the efficient control of pests, a substantial menace to human health and well-being. Tetrastichus hagenowii (Ratzeburg) stands out as the most effective egg parasitoid wasp for controlling American cockroaches, but accurate and stable reference genes for quantitative real-time polymerase chain reaction of T. hagenowii genes are still lacking. In this study, we assessed seven candidate nuclear genes, including α-tubulin (α-TUB), elongation factor-1-alpha (EF-1α), β-actin (Actin), ribosomal protein 49 (RP49), glyceraldehyde-3-phosphate dehydrogenase (GAPDH), nicotinamide adenine dinucleotide (NADH), and elongation factor 2 (EF2) of T. hagenowii. By analyzing expression stability with four algorithms (Delta Ct, geNorm, NormFinder, and BestKeeper), as well as comprehensive ranking with RefFinder, we identified α-TUB as the most stable reference gene for the larval, pupal, female adult, and male adult stages. Subsequently, we estimated the transcript levels of vitellogenin (Vg) and cuticle protein (CP) after normalization with α-TUB across various developmental stages. Significantly higher expression levels of CP and Vg were observed in pupae and female adults, respectively, consistent with previous findings in other insects. This study offers a reliable reference gene for normalizing transcription levels of T. hagenowii genes.