# Adaptive Strategies of Cyrtorhinus lividipennis (Hemiptera: Miridae) to Short-Term High Temperature Stress: Insights from Physiological and Transcriptomic Responses

## TL;DR

This study explores how a beneficial rice pest predator survives short-term extreme heat by analyzing its physiological and genetic responses.

## Contribution

The study reveals novel physiological and transcriptomic mechanisms of heat tolerance in Cyrtorhinus lividipennis.

## Key findings

- Heat exposure increases protective sugars and lipids while altering energy metabolism in C. lividipennis.
- Transcriptomic analysis shows upregulation of heat shock proteins and metabolic pathways under high temperature stress.
- The study identifies key genes and metabolic strategies that help the insect survive extreme heat.

## Abstract

As climate change intensifies, it is becoming increasingly critical to understand how insect natural enemies of crop pests tolerate rising temperatures. Here, we focus on the green mirid bug, a beneficial predator of the major rice pest, the brown planthopper, and examine how it copes with short-term extreme heat. Our experiments show that heat exposure induces the accumulation of protective sugars and lipids and alters energy metabolism by shifting metabolic pathways toward stress defense and energy supply, thereby improving survival. We further find that high temperature induces the expression of several stress-responsive genes, including those that help safeguard cellular structures from damage. Together, these results elucidate the mechanisms underlying short-term extreme heat tolerance in this natural enemy and provide a mechanistic basis for future studies to develop and evaluate field-release strategies in rice systems.

Cyrtorhinus lividipennis, a key natural enemy of the brown planthopper, Nilaparvata lugens, has been observed to tolerate short-term high-temperature exposure; however, the physiological and molecular mechanisms underlying this heat tolerance remain unclear, which may hinder its effective conservation and utilization. Here, we combined physiological and biochemical assays with transcriptome sequencing to elucidate the physiological and molecular mechanisms of heat tolerance in C. lividipennis following 1 h exposure to three temperatures: 26 °C (control), 33 °C (moderate heat stress), and 40 °C (severe heat stress). At 40 °C, sorbitol, trehalose, lipid, and glycogen contents increased significantly, whereas glycerol levels declined. Transcriptomic profiling revealed temperature-dependent DEGs enriched in starch and sucrose metabolism, galactose metabolism, glycerolipid metabolism, oxidative phosphorylation, and protein folding, sorting, and degradation, with pronounced temperature-dependent upregulation of heat shock protein (HSP) gene families. Together, these results demonstrate that C. lividipennis coordinates its heat stress response through soluble polyol accumulation, which is known to act as a compatible osmolytes that help stabilize proteins and membranes and mitigate thermal damage, energy metabolic reprogramming, and HSP-mediated proteostasis, thereby providing a theoretical basis for its conservation and utilization in sustainable paddy agroecosystems.