Sustained-Release Abm@TPP/CMCS Nanopesticide for Enhanced Efficacy Against Cydia pomonella and Reduced Non-Target Toxicity

Abamectin is a widely used insecticide for controlling various pests, including the codling moth (Cydia pomonella). However, with the increasing emphasis on green agriculture, its potential risks to beneficial insects such as honeybees have attracted growing concern. To tackle these challenges, we established a novel nanopesticide delivery system. Specifically, a nanopesticide (Abm@TPP/CMCS) based on carboxymethyl chitosan (CMCS) cross-linked with sodium tripolyphosphate (TPP) was constructed to improve insecticidal efficacy while lowering environmental risks. The prepared nanoparticles presented a spherical and monodisperse morphology with an average size of 85.12 nm (at 0.3 mg/mL) and an encapsulation efficiency of 23.1%. Laboratory bioassays indicated that the nanopesticide exhibited significantly higher toxicity against C. pomonella (LC50 = 0.371 μg/mL) than technical-grade abamectin (LC50 = 0.580 μg/mL), with a corresponding toxicity ratio of 1.563. Its excellent control effect was further confirmed in field trials, with a control efficacy of 85.71% at 10 days after application, which was markedly higher than that of conventional formulations. Notably, nanoencapsulation significantly reduced environmental toxicity: the LC50 value for Apis cerana increased from 0.312 μg/mL (highly toxic) for technical abamectin to 4.162 μg/mL (moderately toxic), and from 684.28 μg/mL to 1484.30 μg/mL for Eisenia fetida. In addition, the nanopesticide showed favorable biosafety toward wheat, maize, and beans, and even promoted root growth in maize. In summary, Abm@TPP/CMCS enhances insecticidal activity against C. pomonella, reduces toxicity to non-target organisms, and enables controlled release, which provides a promising strategy for eco-friendly pest management.