Conduction of AgNPs with different surface charges in pine trees and their prevention and control of pine wood nematode disease

Pine wood nematode disease is caused by pine wood nematodes and is difficult to prevent and control because the nematodes are located inside the trees. In this study, three types of silver nanoparticles (AgNPs) with different surface charges were prepared using Cetyl trimethyl ammonium chloride (CTAC), Polyvinyl pyrrolidone (PVP), and Acacia senegal (GA), and the ion and element concentrations in tree sap were measured after the introduction of AgNPs. Additionally, the effects of the introduction of AgNPs by foliar and soil applications and by trunk injection on the delivery of the AgNPs in the trees were compared. It was found that the LC 50 values of AgNP-GA, AgNP-PVP, and AgNP-CTAC against pine wood nematodes were 0.59, 1.15, and 1.25 mg∙L − 1 , respectively. Our toxicity mechanism studies showed that AgNP can inhibit the activity of acetylcholinesterase and catalase in pine wood nematodes, which is the main origin of the inhibition of pine wood nematode activity by AgNPs. The ion concentration of the sap has a significant impact on the delivery of AgNPs within the tree, with negatively charged AgNP-GA displaying better delivery within pine trees. In addition to conduits and sieve tubes, resin channels and intercellular spaces are likely to be the key sites for AgNP delivery. It was found that trunk injection facilitates the delivery of AgNPs within trees. This study provides an effective strategy for the prevention and control of pine wilt disease, tree trunk pests, and other diseases.