Carrier-Free Codelivery of an Insecticidal Nanosystem Based on Thiamethoxam and Lambda-Cyhalothrin for Sustainable Pest Management

Pesticide delivery of a single active ingredient often faces challenges such as a high risk of pest resistance, limited efficacy, and environmental risks, while pesticide codelivery provides insights for delaying pest resistance, improving effective utilization, and realizing synergistic effects. Carrier-free self-assembled nanotechnology is considered a promising strategy for the development of pesticide nanoformulation due to simple preparation processes, high drug loading rates, and avoidance of potential environmental risks associated with nanocarriers. Herein, codelivery insecticidal nanoparticles (T − L NPs) based on thiamethoxam (THA) and lambda-cyhalothrin (LCN) were fabricated utilizing a coassembly strategy without applying any additives for the sake of efficient utilization and environmental safety. The fabrication process optimized by a single-factor experiment and Box−Behnken design was facile and green friendly. The resulting coassembled nanoparticles exhibited excellent surface morphology, high ζ potential, low surface tension, superior maximum retention, low contact angle, and sound UV stability, which improved their wettability and adhesiveness on plant leaves. The coassembly nanoparticles have pH-responsive release properties, and insecticidal activity experiments demonstrated that the T − L NPs had excellent synergistic biological activity against Aphis gossypii. Furthermore, the coassembly strategy reduced soil leaching and volatility, and mitigated toxicity to nontarget organisms, thereby significantly reducing environmental risk. This study would provide a promising strategy for improving efficient utilization and mitigating environmental impacts of insecticides.