# Characterization of Rice Volatile Secondary Metabolites and Their Role in Modulating the Behavior of the Brown Planthopper (Nilaparvata lugens Stål)

## TL;DR

This study identifies rice plant scents that attract or repel brown planthoppers, a major rice pest, suggesting new eco-friendly pest control methods.

## Contribution

The study identifies specific volatile compounds in rice that influence brown planthopper behavior, offering new pest management strategies.

## Key findings

- Fifteen volatile compounds were more abundant in susceptible rice plants and attracted brown planthoppers.
- One compound was enriched in resistant rice varieties and may act as a repellent.
- Electrophysiological and behavioral assays confirmed attraction or repulsion to specific volatiles.

## Abstract

The brown planthopper (BPH) is a major pest of rice, causing annual yield losses of over 500,000 tons in China. In the present study, we compared the volatile compounds released by rice varieties that are either susceptible or resistant to BPH. We identified 16 volatile compounds associated with susceptibility or resistance, of which 15 were present at higher levels in susceptible varieties. Further experiments confirmed that five of these compounds attract BPH to susceptible plants. These findings suggest that manipulating attractant or repellent scents, as well as breeding rice varieties with optimized volatile profiles, could be effective strategies for BPH management.

Rice volatiles play a crucial role in mediating resistance to the brown planthopper (Nilaparvata lugens Stål, Hemiptera: Delphacidae), a major pest of rice crops. In this study, we analyzed secondary metabolites from rice plants to identify compounds associated with insect behavior. A total of 31 volatile metabolites were detected, among which 16 differed significantly between 51 resistant or susceptible varieties. Fifteen volatiles were more abundant in susceptible plants, while one was enriched in resistant varieties. Electrophysiological (EAG) and Y-tube olfactometer assays revealed that both male and female adults exhibited positive chemotaxis toward five volatiles: Cyclohexanone, 2,2,6-trimethyl-; 3-Cyclohexen-1-one, 3,5,5-trimethyl-; (+)-Isomenthol; Benzoic acid, 2-hydroxy-, methyl ester; and 2-Methoxy-4-vinylphenol. In contrast, male adults were repelled by Benzaldehyde, 3-ethyl-, and 3-Buten-2-one, 4-(2,6,6-trimethyl-1-cyclohexen-1-yl)-. These results indicate that characteristic volatiles serve as functional cues for host selection and may act as phytochemical markers for assessing rice resistance. The findings provide new insights into plant–insect chemical interactions and suggest potential strategies for environmentally friendly pest management, including the use of attractant- or repellent-based approaches and breeding for optimized volatile profiles to control N. lugens.