Functional analysis of vitellogenin and juvenile hormone-mediated regulation in a Psocoptera insect Liposcelis entomophila (Enderlein)

The psocid Liposcelis entomophila has developed strong pesticide resistance and is outbroken frequently, thus seriously threatening food security. Understanding the function of vitellogenin (Vg) and the hormone regulation in L. entomophila will help in obtaining comprehensive knowledge about its reproductive processes and developing new pest management strategies via reproduction disruption. The full-length cDNA of Vg in L. entomophila (LeVg) contains a 5799-bp open reading frame encoding a 1932 amino acid protein. LeVg belongs to the large lipid transfer protein (LLTP) superfamily and has conserved domains and feature motifs of insect Vgs. LeVg is primarily expressed in the fat body of female adults. Notably, feeding on in vitro synthesized dsLeVg significantly suppressed LeVg transcription level. This resulted in inadequately developed ovarioles and reduced fecundity and egg hatchability, suggesting a critical role for vitellogenin in L. entomophila reproduction. Moreover, transcription levels of LeVg and its receptor LeVgR increased in virgin female adults after topical treatment with of 23 ng JH III/insect. This study provides preliminary results about the vitellogenesis of Psocoptera insects and demonstrates that Vg could serve as a promising target for RNAi-based population management of psocids.