Research Of Toxic Effects Of Bifenthrin And Fenvalerate On Corbicula Fluminea

Pyrethroid insecticides are a new generation of high-efficiency broad-spectrum insecticides,which are widely used because of their good insecticidal effect and low toxicity.Although pyrethroid insecticides degrade relatively quickly,due to their large usage and high frequency,there is a large amount of residue in the water environment.In addition,pyrethroid insecticides are targeted pesticides,which have low toxicity to humans and mammals,but have greater toxicity to aquatic organisms.At present,the toxicity of pyrethroid insecticides to fish has been reported,but there are few reports on its toxicity and toxicological effects on benthic organisms.Therefore,Corbicula fluminea,an indigenous benthos in China,was used as the experimental organism in this study.Corbicula fluminea were exposed to bifenthrin and fenvalerate in the high-concentration group(25 ?g/L),medium-concentration group(5 ?g/L)and low-concentration group(1 ?g/L)for 15 days.After 15 d of exposure,the toxic effects of BF and FEN on clams were comprehensively evaluated by multiple indicators such as transcriptome,enzyme activity,apoptotic experiments,comet experiments,histopathology,and siphoning and burrowing behaviorus.With a view to providing a reference basis for monitoring pesticide residues in the water environment.The main results were as follows:1.The exposure of these two pyrethroids caused significant changes in the related genes and pathways of clam immunity,metabolism,and apoptosis.2.In the high-concentration group(25?g/L),the GST and CAT activity,ROS and MDA content increased significantly.This indicates that bifenthrin and fenvalerate exposure activated the clam's antioxidant defense system,but caused oxidative damage.In addition,bifenthrin and fenvalerate exposure significantly reduced the activity of ACh E In the high-concentration group,indicating that these two pyrethroids are neurotoxic.3.The activity of Caspase-8 and Caspase-9 in the bifenthrin and fenvalerate treatment groups in the high-concentration group(25?g/L)increased significantly,and the activity of Caspase-3 was significantly increased in the 25?g/L bifenthrin treatment group.This indicates that bifenthrin and fenvalerate induce apoptosis in the digestive gland cells of clams by activating Caspase-mediated apoptosis.The comet experiment found that the length of Olive tail length increased significantly in the 25?g/L bifenthrin and fenvalerate treatment group,indicating that bifenthrin and fenvalerate were genotoxic.4.The vacuolation of digestive gland tissue was observed in all the treatment groups of bifenthrin and fenvalerate and the degradation of digestive tract in the of 5?g/L and 25?g/L bifenthrin treatment groups,indicating that bifenthrin and fenvalerate had chronic toxicity.5.In the 25 ?g/L BF and FEN treatment groups,the siphoning behaviour was inhibited,indicating that bifenthrin and fenvalerate had behavioural toxicity.To sum up,our results show that exposure to BF,FEN exposure can cause changes in detoxification,antioxidant metabolism,apoptosis,neural pathways,and then lead to changes in the activity of antioxidant biomarkers,histopathological characteristics,cell apoptosis and DNA damage,leading to changes in behaviour.In this study,the toxic effects of pyrethroids on Corbicula fluminea were evaluated comprehensively,which provided a basis for further study on the toxic mechanism of pyrethroids on bivalves.