Effects of Trehalase on the Gene Expression of the Reproductive Regulation Pathway Network and Triglyceride Metabolism in Nilaparvata lugens (Stål)

The high reproductive performance of <i>Nilaparvata lugens</i> (Stål) (Hemiptera: Delphacidae) is one of the key factors contributing to its serious damage. Studies have demonstrated that trehalose hydrolysis, catalyzed by trehalase (TRE), plays an important role in the reproductive regulation of <i>N. lugens</i>. However, it remains unclear how TRE regulates the reproduction of <i>N. lugens</i>. To address this question, the current study was designed to investigate the effects of TRE on the reproductive regulatory network of <i>N. lugens</i>. Specifically, RNA interference (RNAi) was conducted by injecting double-stranded RNA (dsRNA) targeting the TRE genes, and a trehalase inhibitor, validamycin, was used to suppress TRE activity. Subsequently, the relative expression levels of key genes involved in the reproductive regulatory pathway, as well as the triglyceride content in the fat body and ovary, were determined. The results indicated that both dsTREs and validamycin treatment decreased the relative expression of Vitellogenin (Vg) without affecting the expression of its receptor, <i>VgR</i>. However, their impact on the reproductive regulatory network differed: dsTREs injection did not affect the relative expression of <i>JHAMT</i> and <i>Met</i> in the juvenile hormone signaling pathway, but resulted in the upregulation of <i>USP</i> and <i>TOR</i>, and inhibition of <i>InR2</i> and <i>S6K</i>. In contrast, validamycin injection inhibited the expression of <i>Met</i>, <i>USP</i>, <i>EcR</i>, <i>InR1</i>, <i>TOR</i>, and <i>S6K</i>. Both dsTREs and validamycin inhibited the expression of <i>Fas</i>, but only validamycin decreased the ovarian triglyceride content. These findings suggest that the inhibition of <i>TRE</i> leads to alterations in reproductive regulatory signals, thereby reducing the reproductive capacity of <i>N. lugens</i>.