Ecotoxicological effects of the pyrethroid insecticide tefluthrin to the earthworm Eisenia fetida: A chiral view

Abstract

Tefluthrin was the first pyrethroid developed for soil treatment. There was no report about the toxicity to terrestrial invertebrates at the enantiomer level. The main objective of the present study was to investigate the enantiomer-specific acute toxicity to the earthworm Eisenia fetida and potential mechanism via multilevel response. The filter paper contact and the artificial soil method were used to detect the acute toxicity of tefluthrin enantiomers to earthworms. Histopathological examination (H&E), biochemical criterion, and comet assay were used to identify the effects and potential mechanism of toxicity. The order of acute toxicity was Z-cis-(1S,3S)-(−)-tefluthrin < Rac-tefluthrin < Z-cis-(1R,3R)-(+)-tefluthrin. H&E stained images showed that intestinal cells were suffered seriously damaged after exposed to Rac-tefluthrin, and the Z-cis-(1R,3R)-(+)-isomer. Tefluthrin and enantiomers also enantioselectively disturbed reactive oxygen species (ROS) level and enzymatic activity. Additionally, Z-cis-(1R,3R)-(+)-tefluthrin significantly increased the olive tail moment (OTM) and Trail DNA% compared with the control and other treatment groups at the concentration of 0.1 mg/kg was observed. It can be concluded that intestinal damage, body weight changes, DNA damage caused by oxidative stress that might be the primary mechanisms of tefluthrin toxicity to earthworms. The results indicated the rational use of chiral compounds in agriculture to avoid damage to the soil ecosystem.