Temporal expression profiles of PxEcRs (A) and PxUSP (B), respectively, in the last larval instar. Insects were collected at a 6 h interval from the beginning of the 4th larval instar. The mRNA levels were examined by qRT-PCR and normalized to the ribosomal protein rpL32 of P. xylostella (reference gene). Mean ± S.E. represents three independent replications.