Recently, Professor Hanhong Xu and the team of Zhang Zhixiang from the College of Plant Protection at South China Agricultural University have made new advances in the research of green precision pesticides, supported by the National Key R&D Program and the Key R&D Program of Guangdong Province. The relevant research results were published in the Journal of Chemical Engineering and the Journal of Cleaner Production.
The study constructed a nano-drug delivery system targeting tender leaves of crops and harmful organisms using a nano-carrier loaded with pyridaben based on iron-based metal-organic framework materials, effectively enhancing the transport of pyridaben within maize plants. Solutions of iron-based metal-organic framework materials containing surfactants exhibited excellent wetting, deposition, and adhesion properties on maize leaves. Compared to traditional pesticide formulations, the spray application of iron-based metal-organic framework materials showed higher initial deposition rates, longer half-lives on tender and old leaves, and significantly reduced pesticide drift into the environment.
The research emphasizes the necessity of co-application of metal-organic framework nanomaterials with surfactants in field applications. Additionally, this nano-drug delivery system significantly improved the survival rate of natural enemies of fall armyworms—larvae of ladybird beetles—and reduced the impact of pyridaben on the growth and intestinal damage of ladybird beetles. These results highlight the advantages of metal-organic framework delivery systems in enhancing pesticide efficacy, persistence, and safety in multiple dimensions, and provide data on the field application and environmental risks of nano-delivery systems.
The research team also successfully prepared chitosan-based nanoparticles using a chemical cross-linking method to encapsulate pyriproxyfen (PYR), constructing chitosan-based pyriproxyfen nanoparticles. It was found that chitosan-based pyriproxyfen nanoparticles caused sedimentation of microalgae and significantly reduced PYR concentration in water bodies. Laser confocal microscopy and scanning electron microscopy were able to observe the aggregation of nanoparticles on the surface of microalgae, leading to the aggregation of microalgae.
Based on the experiment of adsorbing chitosan-based pyriproxyfen nanoparticles by microalgae and jointly settling to reduce PYR concentration in the culture medium, pond water (rich in microorganisms) was selected as the test water system to detect the content of PYR in the pond water covering after treatment with chitosan-based pyriproxyfen nanoparticles mediated by microorganisms, and to detect the acute toxicity of chitosan-based pyriproxyfen nanoparticles to zebrafish. The results showed that compared to the PYR.S treatment group, the chitosan-based pyriproxyfen nanoparticles treatment group significantly reduced the PYR concentration in the pond water covering, significantly improved the safety of chitosan-based pyriproxyfen nanoparticles to zebrafish, and compared to the PYR.SC group, the impact of chitosan-based pyriproxyfen nanoparticles on the gill tissue of zebrafish was smaller.
The study demonstrated that through the interaction of chitosan-based nanoparticles with microorganisms, chitosan-based pyriproxyfen nanoparticles and microorganisms jointly settle, transferring chitosan-based pyriproxyfen nanoparticles from the covering water to the bottom water, resulting in a reduction of PYR content in the covering water, thus ensuring the safety of non-target aquatic organisms such as fish in the covering water. This research provides new insights into the safety of chitosan-based nano-pesticides for non-target organisms in aquatic environments mediated by aquatic microorganisms.
Related paper information: https://doi.org/10.1016/j.cej.2024.151193
