The function of nuclear receptors in the adult of the red flour beetle (Tribolium castaneum)

Nuclear receptors (NRs) function as key control points in diverse signaling and metabolic pathways. NRs are switched on and off by small molecule ligands with properties similar to insecticides. Therefore, NRs are attractive targets for developing new insecticides. Nineteen canonical and two Knirps family NRs were identified in the genome of Tribolium castaneum. Current studies were conducted to determine the function of NRs in female reproduction during the adult stage of T.castaneum. RNAi analysis showed that seven NRs including E75, DHR3, EcR, USP, SVP, FTZ-F1 and DHR4 are required for vitellogenesis and oogenesis. Knocking-down the expression of these seven NRs affected egg production by reducing the expression level of vitellogenin mRNA as well as affecting the oocyte development. Additional eight NRs including DHR96, DHR51, DHR 38, DHR39, E78, Tailess, Dsf and Knirps are required for successful embryogenesis. These studies show that at least 15 of the 21 NRs identified play key roles in female reproduction. These studies are supported by the USDA-NRI.