Multiresponsive Zein Nanospheres for Avermectin B₂ Delivery: Enhancing Root-Knot Nematode Control and Safety to Nontarget Organisms

Root-knot nematodes are globally prevalent plant-parasitic pests, distinguished by their widespread distribution, extensive host range, and challenging control measures. Avermectin B₂, one of the few effective nematicides available, faces limitations in efficacy and poses environmental concerns due to its eco-unfriendly composition and poor utilization in traditional emulsifiable concentrate (EC) formulations. In this study, we developed core-shell structured Ave B₂-BS@Zein@SC nanospheres, incorporating zein as the carrier, sodium caseinate as the stabilizer, and butyl stearate as the temperature "switch". These nanospheres demonstrated multiresponsive characteristics to temperature, pH, and enzymatic conditions, facilitating rapid pesticide release under elevated temperatures, mildly acidic or alkaline conditions, and in the presence of protease. These controlled-release properties effectively responded to both environmental factors during nematode outbreaks and the intestinal conditions of the nematodes, enhancing pesticide targeting and utilization efficiency. The engineered nanospheres improved the mobility and stability of avermectin B₂ in soil, enabling more comprehensive control of nematodes across broader and deeper soil layers. Additionally, the penetration capability of Ave B₂-BS@Zein@SC into plant roots effectively eliminated nematodes that had already invaded the root system, thereby strengthening crop protection. Crucially, Ave B₂-BS@Zein@SC demonstrated enhanced safety for nontarget organisms. This environmentally conscious, and multiresponsive pesticide nanodelivery system presents a promising strategy for sustainable subterranean pest management.