LmSPARC is essential for oviposition by maintaining oviduct muscle structure and mechanical property in Locusta...

The reproductive success of insects depends on the coordinated function of oviposition-associated muscles. However, the molecular regulators of these muscles, particularly extracellular matrix (ECM) components, remain poorly understood. In this study, we identified a gene encoding the ECM glycoprotein SPARC through transcriptomic analysis of key oviposition muscles in Locusta migratoria. Tissue-specific expression analysis showed that LmSPARC was highly expressed in these oviposition-associated muscles of adult females. RNA interference-mediated knockdown of LmSPARC in fifth-instar nymphs resulted in complete oviposition failure in adults, characterized by retained mature oocytes and marked abdominal distension. Although abdominal extension and ovipositor digging behaviors were unaffected, the mechanical strength (maximum breaking force) of the lateral oviduct was severely reduced following LmSPARC knockdown. Histological analysis further revealed significant thinning and disorganization of the circular muscle layer of oviduct. Collectively, our findings demonstrate that LmSPARC is essential for maintaining the structural integrity and tensile properties of oviduct muscles, thereby ensuring successful egg expulsion. This study reveals a novel, muscle-related role of SPARC in insect reproduction and provides a potential target for RNAi-based locust management strategies.