# Temporal Dynamics of Bacterial Communities in Ectropis grisescens Following Cryogenic Mortality

## TL;DR

This study tracks how bacteria in a tea-leaf pest change after the insect is killed by freezing, revealing patterns that could help develop new pest control methods.

## Contribution

The first ecological profile of postmortem microbial succession in a lepidopteran pest, Ectropis grisescens.

## Key findings

- Microbial diversity declined over time, while richness initially increased before decreasing.
- Wolbachia, the dominant endosymbiont, gradually disappeared after host death, whereas Enterobacter remained abundant.
- Non-dominant genera like Lysinibacillus and Sporosarcina temporarily increased in abundance before returning to baseline.

## Abstract

Ectropis grisescens is a major leaf-feeding pest in Chinese tea plantations, causing severe yield and quality losses. Current control methods, including chemical and biological agents, face challenges such as environmental risks and resistance. Bacteria play crucial roles in insect physiology and offer potential targets for sustainable pest management, yet their postmortem dynamics in E. grisescens remain poorly understood. This study used 16S rRNA sequencing to analyze postmortem bacterial community changes in E. grisescens cadavers at 0, 7, and 21 days after cryogenic mortality. We found that microbial diversity declined over time, while richness initially increased before decreasing. Wolbachia, the dominant endosymbiont, gradually disappeared after host death, whereas Enterobacter persisted as a major constituent. Non-dominant taxa such as Lysinibacillus and Sporosarcina temporarily increased by day 7 before returning to baseline levels. This research provides the first ecological profile of postmortem microbial succession in a lepidopteran pest, offering insights for developing novel pest control strategies.

Ectropis grisescens (Lepidoptera: Geometridae) is a destructive pest in tea plantations, leading to significant economic losses through defoliation. Existing control strategies, including chemical insecticides and biological agents, are often limited by environmental concerns, resistance, and variable efficacy. Recent evidence suggests that bacteria influence insect physiology and could be leveraged for pest management, but the postmortem microbial ecology of E. grisescens remains uncharacterized. In this study, we employed 16S rRNA sequencing to investigate temporal changes in the bacterial communities of E. grisescens cadavers at 0, 7, and 21 days following cryogenic mortality. Our results indicate a time-dependent decline in microbial diversity, while species richness initially increased before subsequent reduction. The dominant endosymbiont Wolbachia gradually diminished after host death, whereas Enterobacter remained abundant. Notably, non-dominant genera including Lysinibacillus and Sporosarcina exhibited a transient increase in abundance at day 7 before reverting to control levels by day 21. This study presents the first comprehensive analysis of postmortem microbial succession in a lepidopteran system, highlighting dynamic shifts in bacterial composition and offering potential avenues for microbiome-based pest management strategies.