Functional Characterization of Nuclear Receptor MuFTZ-F1 in the Bean Flower Thrips, Megalurothrips usitatus

The development of novel control strategies for the major cowpea pest Megalurothrips usitatus requires a deeper understanding of its critical molecular regulators. The nuclear receptor Fushi-tarazu factor 1 (FTZ-F1) is a conserved master regulator of insect development and reproduction, yet its function in M. usitatus remains uncharacterized. In this study, we investigated the expression and functional role of MuFTZ-F1 in this pest. RT-qPCR analysis revealed ubiquitous MuFTZ-F1 expression across all developmental stages and in major adult tissues. RNA interference (RNAi)-mediated knockdown of MuFTZ-F1 in the 2nd instar nymphs caused severe developmental defects, including impaired eclosion and significantly increased mortality. Mechanistically, silencing led to a significant reduction in the molting hormone ecdysone, accounting for the observed molting arrest. Furthermore, MuFTZ-F1 knockdown significantly decreased dopamine titers in both nymphs and female adults, suggesting its involvement in regulating this key biogenic amine beyond developmental processes. Our results provide the first functional evidence that MuFTZ-F1 is indispensable for nymphal development and survival in M. usitatus, mediated through the regulation of ecdysone. The profound lethal effect of MuFTZ-F1 silencing underscores its promise as a target for RNAi-based pest management strategies against this economically important pest.