Co-delivery of neonicotinoid and synergist by a nanocarrier enabling bidirectional systemic translocation for...

Neonicotinoid insecticides are globally used, but their effectiveness is increasingly challenged by both rising insecticide resistance and growing environmental risks. IPPA08 is a neonicotinoid-specific synergist to enhance neonicotinoid efficacy and manage insecticide resistance. In this study, we developed a novel nanopesticide, DMSNs-NIT-PEI-IPPA08, based on dendritic mesoporous silica nanoparticles (DMSNs) to co-deliver nitenpyram (NIT) and IPPA08 to control two sap-feeding pests Nilaparvata lugens and Schizaphis graminum. The formulation enables bidirectional translocation within plants, effective delivery to pest feeding sites, and augmenting synergistic toxicity. Three nanoformulations with NIT:IPPA08 ratios of 7.94:1, 2.66:1 and 1.21:1 were prepared, among which the 1.21:1 ratio showed the lowest LC₅₀. DMSNs-NIT-PEI-IPPA08 exhibited higher insecticidal activity against both pests compared to NIT alone and a NIT-IPPA08 mixture with the same ratio. A key finding was the lateral transport of nanoparticles to leaf sheaths, which would potentially contributed to plant physical defense against insects. The results provide a novel strategy for the dosage reduction and efficacy enhancement of neonicotinoids using multi-component nanopesticides.