A Leaf-Adhesive, pH-Responsive Emamectin Benzoate Nanopesticide for Enhanced Efficacy and Reduced Toxicity

A precise and low-toxicity pesticide delivery system is essential to enhancing pesticide efficacy and sustainability. Herein, a facile strategy is developed to construct leaf-adhesive and pH-responsive emamectin benzoate nanopesticides (EB NPs), in which Ca2+ cross-links copolymer surfactant/nonionic surfactant/sodium alginate in coacervates. The uniform nanosize of EB NPs enables them to penetrate the microstructure of plant leaves, thereby improving their deposition and antiwashing ability. Moreover, the pH-responsive EB NPs facilitate precise release of encapsulated emamectin benzoate (EB) in the alkaline midgut (pH 9–10) of Plutella xylostella larvae by displacing Ca2+ in the alginate nanoskeleton, along with the nanostructure disintegration. Notably, the acute toxicity of EB NPs to zebrafish is reduced to less than one-seventh that of commercial EB microemulsion formulation. This nanopesticide approach shows excellent potential to improve the pesticide efficacy and safety.