# Transcription Factor CcFoxO Mediated the Transition from Summer Form to Winter Form in Cacopsylla chinensis

## TL;DR

This study explores how the transcription factor CcFoxO helps the insect Cacopsylla chinensis transition from summer to winter form under cold stress.

## Contribution

The study identifies CcFoxO as a key regulator of seasonal polyphenism in Cacopsylla chinensis, linking it to energy storage and morphological changes.

## Key findings

- CcFoxO is responsive to low temperatures and regulated by CcTRPM.
- CcFoxO influences energy storage by accumulating triglycerides and glycogen.
- Knockdown of CcFoxO leads to high mortality and failed seasonal transition.

## Abstract

Amid global climate change featuring erratic temperature fluctuations, insects adapt via seasonal polyphenism, essential for population sustainability and reproductive success. Cacopsylla chinensis, influenced by environment variations, displays a distinct summer form and winter form distinguished by significant morphological variations. Previous studies have highlighted the role of temperature receptor CcTPRM in orchestrating the transition in response to 10 °C temperature. Nevertheless, the contribution of the transcription factor FoxO in this process has remained ambiguous. Here, we aimed to explore the correlation between C. chinensis FoxO (CcFoxO) and cold stress responses, while identifying potential energetic substances for monitoring physiological shifts during this transition from summer to winter form under cold stress by using RNAi. Initially, CcFoxO emerges as responsive to low temperatures (10 °C) and is regulated by CcTRPM. Subsequent investigations reveal that CcFoxO facilitates the accumulation of triglycerides and glycogen, thereby influencing the transition from summer form to winter form by affecting cuticle pigment content, cuticle chitin levels, and cuticle thickness. Thus, the knockdown of CcFoxO led to high mortality and failed transition. Overall, our findings demonstrate that CcFoxO governs seasonal polyphenism by regulating energy storage. These insights not only enhance our comprehension of FoxO functionality but also offer avenues for environmentally friendly management strategies for C. chinensis.