<i>Nilaparvata lugens</i> (Hemiptera: Delphacidae) feeding alters carbohydrate-redox homeostasis of rice plants grown under elevated CO2

The rising atmospheric carbon dioxide (CO2) concentration due to global climate change may affect both plants and herbivorous insects. In this study, we explored the interactions between the feeding behavior of Nilaparvata lugens (Stål, 1854) (Hemiptera: Delphacidae) and rice plant responses-specifically photosynthesis, non-structural carbohydrates (NSCs), and oxidative stress under elevated CO2 (eCO2) conditions. The results showed that without N. lugens infestation, eCO2 enhanced rice plants' photosynthesis parameters and promoted NSCs accumulation and metabolism, while suppressing oxidative stress parameters compared to ambient CO2 (aCO2). However, under N. lugens infestation, eCO2-grown rice plants' photosynthesis parameters and NSCs levels declined, while oxidative stress parameters increased, ultimately surpassing those in aCO2-grown rice plants by 24 h. Electrical penetration graph (EPG) analysis revealed that N. lugens increased feeding activity on rice plants under eCO2 within the first 0 to 24 h, but reduced feeding between 24 and 36 h. Mantel test further verified that the feeding behavior of N. lugens was closely related to photosynthesis, NSCs and oxidative stress of rice plants under eCO2. This study demonstrates that eCO2 dynamically alters the interactions between rice plants and N. lugens by simultaneously modulating plant resource allocation and oxidative stress responses, thereby driving time-dependent shifts in the feeding behavior of N. lugens. These findings provide novel insights into how climate change may reshape trophic interactions in agroecosystems through physiological feedback mechanisms.