Enantioselective Environmental Behavior Of Dinotefuran Enantiomers And Their Ecological Toxicology Effects

Neonicotinoid insecticides have become the largest sales pesticides in the world.Dinotefuran is the latest generation of neonicotinoid chiral insecticide with broad application prospect.However,there is few researches focus on the environmental safety of dinotefuran from the enantiomer level.In this project,the selective degradation behavior,the selective ecological effects on soil microorganisms,the selective toxic effects on soil typical non-target organism-earthworm of dinotefuran enantiomers in soil were studied.The main purpose of the present study was to provide a theoretical reference for the environmental safety of dinotefuran in the soil ecosystem.The main results were as follows:(1)During the whole exposure period,Rac-dinotefuran,R-dinotefuran and S-dinotefuran degraded slowly in the unsterilized soil with the half-life of 70.7,61.3 and 74.5 d,respectively.With the increase of exposure time,there were selective degradation behavior among Rac-dinotefuran,R-dinotefuran and S-dinotefuran in the unsterilized soil.However,Rac-dinotefuran,R-dinotefuran and S-dinotefuran almost didn’t degrade in the sterilized soil during the whole exposure period.(2)The community abundance changed significantly after exposure to R-dinotefuran and S-dinotefuran.Moreover,the number of unique genes in S-dinotefuran treatment was significantly higher than those in the R-dinotefuran treatment.The function annotation of unique genes indicated that S-dinotefuran had significant influences on the metabolism of biomacromolecules in microorganisms,such as proteins,carbohydrates and lipids,especially the proteins and carbohydrates.This result indicated that there were selective ecological effects between R-dinotefuran and S-dinotefuran in the unsterilized soil.(3)The acute toxicity of Rac-dinotefuran,R-dinotefuran and S-dinotefuran on the soil typical non-target organism-earthworm was S-dinotefuran>Rac-dinotefuran>R-dinotefuran.In the subacute toxicity test,Rac-dinotefuran,R-dinotefuran and S-dinotefuran had significant inhibitory effect on the growth and reproduction of earthworms at 1.0 mg/kg after 42 d exposure.Moreover,Rac-dinotefuran,R-dinotefuran and S-dinotefuran induced the excessive production of ROS in earthworm cells,resulting in the oxidative damage in biomacromolecules and significant changes in the expression of functional genes.The transcriptome sequencing results showed that the number of differentially expressed genes in S-dinotefuran treatment was significantly higher than those in the R-dinotefuran treatment.Moreover,S-dinotefuran had stronger interactions to the biomacromolecules,such as proteins,enzymes and nucleic acids and a stronger influence on the function of endoplasmic reticulum(ER),finally resulting in significant toxic effects on earthworms.