Effects of three diamides (chlorantraniliprole, cyantraniliprole and flubendiamide) on life history, embryonic development and oxidative stress biomarkers of Daphnia magna.

The diamides have become one of the most promising new classes of insecticides. In this study, we evaluated the toxicity of three diamides (chlorantraniliprole, cyantraniliprole and flubendiamide) to Daphnia magna. The acute toxicity test showed that the 48-h EC50 of chlorantraniliprole, cyantraniliprole and flubendiamide were 8.5, 23.9 and 63.5 μg/L, respectively. Biochemical measurements revealed a significant increase in reactive oxygen species (ROS) in D. magna after acute exposure to the three diamides. A significant decrease in activities of antioxidant enzymes superoxide dismutase (SOD) and glutathione peroxidase (GPx) was observed, which was consistent with the down-regulated transcription of antioxidant genes sod and gpx. Catalase (CAT) activity exhibited a significant increase while the related gene cat showed no obvious change in daphnids acutely exposed to the three diamides. The chronic test revealed that the three diamides could cause lethal and sub-lethal effects on daphnids within constricted range of concentrations at μg/L level. The 21-d EC50 of chlorantraniliprole, cyantraniliprole and flubendiamide for mobility were 5.0, 13.6 and 36.8 μg/L, respectively. The chronic LOEC of chlorantraniliprole, cyantraniliprole and flubendiamide based on survival, growth and reproduction of D. magna were 4.05, 10.24 and 19.36 μg/L, respectively. Moreover, these three diamides can induce severe developmental abnormalities in D. magna embryos including underdeveloped second antennae, curved tail spine and abnormal body region after acute exposure and the 48-h EC50 were 6.2, 14.1 and 30.8 μg/L for chlorantraniliprole, cyantraniliprole and flubendiamide respectively. Our findings indicate that even low levels of diamides can pose ecological risks to aquatic ecosystems.