Functional characterization of PxCBR1-L reveals its essential role in multi-stress tolerance in a cosmopolitan pest.

Climate change and intensive pesticide use impose combined stress on agricultural pests. To investigate the genetic basis of stress resilience in Plutella xylostella, we focused on PxCBR1-L, a carbonyl reductase gene highly expressed in detoxification tissues and upregulated under heat and insecticide exposure. Using clustered regularly interspaced short palindromic repeats (CRISPR) / CRISPR-associated nuclease 9, we generated PxCBR1-L knockout lines. Mutants exhibited impaired development, reduced survival, shortened lifespan, and decreased fecundity. Biochemically, knockout strains showed elevated reactive oxygen species and reduced superoxide dismutase, catalase, Carboxylesterase, glutathione S-transferase, and P450 activities, indicating compromised antioxidant and detoxification functions. Heat-stressed mutants showed lower critical thermal maximum, reduced survival, and increased insecticide sensitivity. Moreover, mutants exhibited significantly higher supercooling and freezing points, and elevated water loss and mortality under desiccation stress, suggesting reduced cold and drought tolerance. These findings reveal that PxCBR1-L is essential for maintaining systemic physiological homeostasis under multiple environmental stresses, and its disruption leads to broad vulnerability. This work identifies PxCBR1-L as a potential target for integrated pest management in a changing climate.