Targeting the Type 1 Tyramine Receptor LsTAR1 Inhibits Reproduction, Feeding and Survival in the Small Brown Planthopper Laodelphax striatellus

<i>Laodelphax striatellus</i> is one of the most destructive rice pests. However, the functions of TARs in rice pests remain largely unknown. Here, we cloned <i>LsTAR1</i> from <i>L. striatellus</i>. LsTAR1 shares considerable sequence identity with its orthologous receptors, and clusters closely with its corresponding receptor groups. <i>LsTAR1</i> was most highly expressed in the egg stage and brain of <i>L. striatellus</i>. Knockdown of <i>LsTAR1</i> by RNA interference (RNAi) prolonged the preoviposition and oviposition period, and reduced the fecundity. Furthermore, <i>LsTAR1</i> knockdown significantly decreased the mRNA levels of <i>vitellogenin</i> (<i>LsVg</i>) in the fat body and ovary, and increased the transcript levels of <i>Vg receptor</i> (<i>LsVgR</i>) in the ovary, as well as altered the expression levels of genes related to juvenile hormone (JH) and 20-hydroxyecdysone (20E) pathway. Additionally, <i>LsTAR1</i> knockdown markedly reduced the honeydew excretion of the adults and affected the expression of neuropeptide signaling genes involved in insect feeding. Notably, disruption of <i>LsTAR1</i> signaling via RNAi or an antagonist reduced the survival rates of <i>L. striatellus</i>. This study uncovers the crucial roles of <i>LsTAR1</i> in reproduction, feeding, and survival in <i>L. striatellus</i>, and highlights its potential as a promising target for developing novel pest management strategies.