Multi-directional selective toxicity effects on farmland ecosystems: A novel design of green substitutes for neonicotinoid insecticides

摘要

Environmental enrichment abilities and chronic sub-lethal effects on non-target organisms caused by neonicotinoid insecticides (neonics) have been challenging issues for environmental pollution. In other words, the renewal of insecticides, especially the research of green substitutes, is one of the best ways to protect the environment and non-target organisms. In this research, a complete design and screening system for green substitutes of neonics was established through the contour map, homology modeling, molecular docking, and molecular dynamics. Contour maps were constructed to obtain the substituted sites and groups, and the results revealed that introducing large, negative/positive or hydrophobic groups can reduce the enrichment abilities of neonics. Using Compound 18 as a template, 58 derivatives with lower enrichment abilities were designed (decreased by 0.55%-57.42%). Then, human health risks were assessed based on multimedia exposure model of pollutants, and the HI values of five derivatives were found to be 1 and the RI values were 1 x 10(-6), indicating that the non-carcinogenic risks of the neonics derivatives were completely acceptable, and the carcinogenic risks were negligible. Furthermore, the multi-selective toxicity of five derivatives in farmland ecosystems was studied using homology modeling and molecular docking, and Derivative-1, Derivative-3, Derivative-10, and Derivative-56 showed multi-selective toxicity on farmland ecosystems. Specifically, the toxicity effects on pests and grubs were enhanced (increased by 1.44%-12.58%), whereas the chronic sublethal effects on bees and earthworms were reduced (decreased by 0.29%-27.18%). Finally, the damage to soybean leaves caused by four derivatives was analyzed by molecular dynamics, and the solvent accessible surface area of the above four derivatives was found to be smaller than that of Compound 18, indicating that the derivatives decomposed more easily in soybean crops, thus reducing the damage to the soybean's leaf surface. This study provides a significance reference in designing green substitutes for neonics to protect the envi-ronment and ecosystem. (C) 2020 Elsevier Ltd. All rights reserved.