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

## TL;DR

This study shows that targeting the LsTAR1 receptor in a rice pest disrupts reproduction, feeding, and survival, offering a new approach for pest control.

## Contribution

The study identifies LsTAR1 as a novel target for pest control by demonstrating its role in reproduction, feeding, and survival in Laodelphax striatellus.

## Key findings

- Knockdown of LsTAR1 reduced reproduction, feeding, and survival in Laodelphax striatellus.
- LsTAR1 knockdown altered gene expression related to reproduction and feeding pathways.
- Disruption of LsTAR1 signaling via RNAi or antagonists reduced pest survival rates.

## Abstract

In insects, the biogenic amine tyramine (TA) regulates various physiological and behavioral processes through tyramine receptors (TARs), which are G protein-coupled receptors (GPCRs). Insect TARs are classified into three groups: TAR1, TAR2, and TAR3, based on their structural, pharmacological, and biochemical properties. Among TARs, TAR1 has attracted much attention owing to its diverse functions and potential as a novel target. Here, we investigated the effects of targeting the type 1 tyramine receptor gene (LsTAR1) in the small brown planthopper Laodelphax striatellus, and found that knockdown of LsTAR1 inhibited the reproduction, feeding behavior, and survival of L. striatellus. These results deepen our understanding of the functions of insect TARs and provide the theoretical basis for the development of TARs as potential targets for insect pest control.

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