Bifunctional CMCS bioswitch: A stimuli-responsive platform neutralizing lambda-cyhalothrin resistance and mitigating ecological risk

Developing multifunctional pesticide delivery systems represents a crucial strategy to address challenges in conventional pesticide applications, including low active ingredient utilization, resistance development, and environmental risk accumulation. This study developed a pH/enzyme dual-responsive nano-delivery system based on carboxymethyl chitosan (LCT@CMCS-g-PCL) for smart targeted delivery and controlled release of lambda-cyhalothrin (LCT). The system's environmental stability, foliar affinity, and stimuli-responsive release behavior were systematically characterized. LCT@CMCS-g-PCL nanoparticles exhibited an average size of 312.5 nm with 23.69 % drug loading and excellent storage stability. Notably, the system showed over 2-fold enhanced resistance to enzymatic degradation and extended photodegradation half-life of LCT from 37.5 h to 187.9 h. Compared with commercial microemulsion (LCT ME), the system showed 17.06 % improvement in foliar deposition efficiency. In vitro release studies confirmed environmental responsiveness, with stable deposition under acidic conditions, triggered release in the alkaline microenvironment, coupled with enzyme activity modulation to delay resistance. Bioassays demonstrated superior pest control efficacy against Plutella xylostella larvae compared to conventional formulations, with the LC 50 value reduced by 39.7 %. Biosafety evaluations confirmed the relative safety for human cells and adult zebrafish, with minimal disturbance to aquatic microbial communities. This study provides an effective strategy for precision pest control, resistance management and environmental risk management in agriculture.