Antheraea pernyi silk fibroin fiber-reinforced biodegradable mulch film for controlled herbicide delivery and sustainable weed suppression

The prolonged use of plastic mulch films and chemical herbicides has led to persistent soil contamination and rising ecological risks. Meanwhile, existing biodegradable mulch films often suffer from incomplete degradation and potential microplastic formation, limiting their practical sustainability. In this study, a multifunctional biodegradable chitosan/silk fibroin (SF) composite film (CS) was developed by incorporating SF fiber powder derived from waste Antheraea pernyi cocoons generated from large-scale natural enemy mass production into a chitosan matrix. Structural characterization indicated that SF fibers were uniformly dispersed within the matrix, forming a reinforced network that significantly enhanced mechanical strength and light-shielding properties. This compact structure enabled a high loading capacity for pendimethalin (PL) (90.70%) and a controlled release behavior, only 63.26% of PL was released within 26 h, which was 34.52% lower than that of the PL-loaded chitosan film. In addition, leaching studies demonstrated that CS effectively retained PL, thereby reducing its migration and accumulation in soil while prolonging herbicidal activity. Pot experiments revealed that CS achieved 92.59% weed suppression, approaching complete weed control, using only one-quarter of the recommended commercial herbicide dosage, while simultaneously promoting crop growth. Ecotoxicological and biodegradation evaluations further confirmed that CS was readily biodegradable and exhibited no adverse effects on earthworms or Chlorella vulgaris, while potentially supporting soil ecological functions through enhanced earthworm growth. This study provides a sustainable valorization strategy for waste silkworm cocoons and offers a multifunctional biodegradable mulch film for efficient weed control with reduced herbicide input and improved environmental safety.