Eco engineering of nano-enabled plant protection strategies for sustainable agriculture – ORGANIC

How to sustainably feed 10 billion people by 2050? Agriculture relies on pesticides to control diseases, insect pests and weeds. Brazil ranks 3rd on the use of pesticides and France is in 6th place (United Nations Food and Agriculture Organization). The use of fertilizers contributes to pollute rivers, groundwater, promotes eutrophication and air pollution. Pesticides cause 355,000 death yearly in the world, by overexposure/misuse, and affect non-target wildlife and biodiversity.
Because the nano dimension improves the properties of materials, nanotechnology can help to design smart nanopesticides that are potentially less harmful to the environment and non-target organisms. Through a transdisciplinary approach, combining varied and complementary expertise, the Franco-Brazilian team will develop the ecodesign of hybrid nanopesticides, based on organic-inorganic nanoparticles such as biopolymers and metal, prepared by chemical and biogenic routes. The differences in structure make it interesting to address these particles in the same project: biogenic HNPs are formed by a metal core surrounded by a corona of bio(macro)molecules, some with enzymatic activities, whereas synthetic hybrid nanopesticides are formed by an organic biopolymer core, grafted by metal nanoparticles.
Smart synthetic hybrid nanopesticides based on biocompatible and biodegradable biopolymers will be developed for the release of metallic ions or nanoparticles as pesticide in response to variations in stress conditions (such as pH or redox potential) induced by the plant. In these conditions it is expected that the hybrid nanopesticides release the active metallic form only near the root during its growth or in the apoplasm, in response to a pathogen attack.
In this way, this project will address the synthesis of new hybrid nanopesticides, focusing on biogenic and synthetic (green synthesis) routes. A safer-by-design approach, combining an evaluation of the efficacy with early impact analysis on non-target organisms, will allow selecting the best hybrid nanopesticides candidates. The toxicity of hybrid nanoparticles on human cells will be the first selection stage. The antifungal activity of hybrid nanoparticles will be evaluated in vitro on plant pathogenic fungi to determine the effective concentration ranges. Wheat will be chosen as a plant model, as this crop is relevant in both countries. Then, eco-compatibility will be analyzed on terrestrial non-targets such as plants and nematodes, soil and plant microbiota, and soil fertility. In addition, we will characterize the biotransformation of hybrid nanopesticides in plants, and nematodes by X-ray and hyperspectral imaging and laser ablation coupled with ICP-MS and their residues in soils by ICP-MS. The best hybrid nanopesticides candidates will be evaluated in planta in infection assays by pests (larvae) and by pathogens. Multivariate analysis will allow us to hierarchize the hybrid nanopesticides, based on a balance of environmental compatibility/efficacy/cost. To address the water compartment, which is a secondary non-target of pesticides, risk assessment will be performed on a selection of two hybrid nanopesticides, using aquatic mesocosms and chronic doses with leachates from soils planted and treated with these hybrid nanopesticides. We will also analyze the efficiency in in field or greenhouse assays from seeds to ear, in challenge conditions.
Taking advantage of the diversity of hybrid nanopesticides surface properties that will be generated in this proposal, this study will allow to better understand the interactions of nanoparticles with the terrestrial and aquatic environment and to identify structure-property-impact relationships of nanoparticles in the environment. This knowledge will serve as a guide for the ecodesign and regulation of nanopesticides, promoting economic, environmental and societal benefits in order to address the agriculture challenges and sustainability.