AbstractThe juvenile hormone (JH) plays a vital role in the regulation of a number of physiological processes, including development, reproduction, and ovarian maturation. Isopentenyl pyrophosphate isomerase (IPPI) is a key enzyme in the biosynthetic pathway of JH. In this study, we identified an isopentenyl pyrophosphate isomerase protein fromBemisia tabaciand named itBtabIPPI. The open reading frame (ORF) ofBtabIPPIis 768 bp and encodes a protein of 255 amino acids that contains a conserved domain of the Nudix family. The temporal and spatial expression profiles showed thatBtabIPPIwas highly expressed in the female adults.RNA interference (RNAi)-mediated silencing ofBtabIPPIreduced JH titers and the relative expression of vitellogenin receptor (VgR) and JH signaling pathway genes, resulting in a dramatic reduction in fecundity and hatchability. These results indicate that theBtabIPPIgene plays an important role in the female fecundity ofB. tabaci. This study will broaden our understanding of the function of IPPI in regulating insect reproduction and provide a theoretical basis for targeting IPPI for pest control in the future.