# Immune and Metabolic Responses in Ectropis grisescens Infected by Metarhizium anisopliae: Insights from Transcriptome and Metabolome Analyses

## TL;DR

This study explores how tea geometrid moths respond to a natural fungus that kills them, revealing immune and metabolic changes that could help develop better eco-friendly pest control methods.

## Contribution

The study provides novel molecular insights into the immune and metabolic responses of Ectropis grisescens to Metarhizium anisopliae infection.

## Key findings

- 2409 differentially expressed genes were identified in infected tea geometrids, with 119 significantly enriched in immune-related processes.
- 1860 differentially accumulated metabolites were detected, with 236 significantly enriched in 82 KEGG pathways.
- Immunity-related and detoxifying enzyme-related genes were activated in response to the fungal infection.

## Abstract

The tea geometrid (Ectropis grisescens) is one of the most destructive defoliators in Chinese tea plantations, resulting in significant economic losses. The overuse of insecticides might lead to a series of food safety problems and environmental issues. Biocides, such as Metarhizium anisopliae, are one of the most environmentally friendly alternatives, which have been widely used in agricultural pest control. We isolated and identified a highly virulent strain of M. anisopliae against tea geometrid, while its insecticidal molecular mechanism remains unclear. Here, we combined transcriptome and metabolome analysis, analyzing the changes of immunity-related genes and metabolites in E. grisescens that were infected by M. anisopliae, which provide molecular insights into the insect–pathogen interaction.

The tea geometrid (Ectropis grisescens) is a significant pest in Chinese tea plantations. Although Metarhizium anisopliae serves as an environmentally friendly biocontrol agent against E. grisescens, the molecular mechanisms underlying the insect’s immune response remain unclear. This study investigates changes in immunity-related genes and metabolites in E. grisescens larvae infected with a virulent strain of M. anisopliae through transcriptome sequencing and metabolome analysis. We identified 2409 differentially expressed genes (DEGs) at 48 h post-infection, with 1611 genes up-regulated. GO analysis revealed that 119 DEGs were significantly enriched in immune-related processes. Additionally, 1860 differentially accumulated metabolites (DAMs) were detected, including 652 up-regulated and 1208 down-regulated metabolites, with 236 significantly enriched in 82 KEGG pathways. These findings indicate the activation of immunity-related and detoxifying enzyme-related genes, providing new insights into the physiological and biochemical responses of insects to biopesticides and potential targets for controlling tea geometrid.