Systemic Stereoselectivity Study of Etoxazole: Stereoselective Bioactivity, Acute Toxicity, and Environmental Behavior in Fruits and Soils

This is the first systemic assessment of the stereoselectivity of etoxazole enantiomers. Etoxazole’s stereoselective bioactivity was assessed against target organisms (Tetranychus urticae eggs and Tetranychus cinnabarinus eggs), and its acute toxicity was assessed toward nontarget aquatic organisms (Daphnia magna and Danio rerio). Additionally, stereoselective elimination was investigated in three species of fruits (grape and strawberry grown in a greenhouse and apple grown in an open field) and in field soil. The ovicidal activity of (+)-(S)-etoxazole against Tetranychus urticae and Tetranychus cinnabarinus eggs was about 16 and 24 times higher, respectively, than that of (−)-(R)-etoxazole. Inconsistent order of etoxazole isomer toxicity was found toward different aquatic organisms: (+)-(S)-etoxazole showed nearly 8.7 times higher acute toxicity than (−)-(R)-etoxazole toward Daphnia magna, whereas (−)-(R)-etoxazole was ∼4.5 times more toxic to Danio rerio than (+)-(S)-etoxazole. Stereoselective degradation of etoxazole enantiomers showed significant variation in various fruits and field soil. The (+)-(S)-etoxazole was preferentially dissipated in grape and strawberry fruits grown under greenhouse condition, whereas (−)-(R)-etoxazole degraded faster than its antipode in apple fruits and soils under open-field condition. Overall, the stereoselectivity of etoxazole enantiomers should be fully considered in comprehensive environmental health risk in future work.