Validation of endogenous reference genes for insecticide-induced and developmental expression profiling of Liposcelis bostsrychophila (Psocoptera: Liposcelididae)

Four housekeeping genes named Lb beta-Actin1, Lb beta-Actin2, Lb alpha-Tubulin, and LbGapdh were cloned from Liposcelis bostrychophila using the combined techniques of reverse transcriptase-PCR (RT-PCR) with rapid amplification of cDNA ends (RACE). The GenBank accession numbers were FJ196622, FJ447483, FJ595242, and FJ595241, respectively. The full-length cDNA of Lb beta-Actin1 was a 1,772 bp sequence with an open reading frame (ORF) encoded 376 amino acids, while Lb beta-Actin2 was 1,350 bp in length containing an ORF encoded 376 amino acids. Furthermore, the 1,565 bp cDNA of Lb alpha-Tubulin had an ORF of 1,350 bp encoding 450 amino acids. And LbGapdh possessed an ORF of 333 amino acids. Sequences analysis and phylogenetic trees generated from the nucleotide sequences of their coding regions revealed a relationship that was closer to other insects than to mammals. The four genes together with 18S rRNA were quantified for transcription stability in L. bostrychophila, and the geNorm software ranked from the most to least were Lb beta-Actin1 > LbGapdh > Lb alpha-Tubulin > Lb beta-Actin2 > Lb18S rRNA for deltamethrin induction, while ranked Lb beta-Actin1 > Lb alpha-Tubulin > Lb beta-Actin2 > LbGapdh > Lb18S rRNA for the different developmental stages.