Preliminary Study On The Toxic Effect Of Thiacloprid On Zebrafish

Neonicotinoids have become one of the most widely used insecticides because of their outstanding effects on the control of stinging insects,coleoptera pests and some micro-lepidoptera pests.Since the introduction of imidacloprid in 1991,neonicotinoid insecticides have rapidly grown into one of the major insecticides at home and abroad,accounting for 20% of the world's pesticide sales and 15% of China's total pesticide production.Released in the European Union in the risk assessment,many crops are due to imidacloprid,thiamethoxam,thiamethoxam amine in major new neonicotinoid medicament residue leading to its to bees with high risks,so as to protect the environment and limited the imidacloprid,thiamethoxam,thiamethoxam amine of pesticide products promote the use,as an important object of agricultural exports in our country,the European Union a ban on Chinese agricultural products,export trade caused a greater impact.As one of the safest products of neonicotinoid insecticides for bees,thiamethoxylline has become a substitute for imidacloprid,thiamethoxylin,thiamethoxamine,etc.,which has been widely promoted and used in China in recent years.As one of the safest products of neonicotinoid insecticides for bees,thiamethoxylline has become a substitute for imidacloprid,thiamethoxylin,thiamethoxamine,etc.,which has been widely promoted and used in China in recent years.Experimental studies have shown that 80% to 98.4% of the residues of thiacloprid remain in the environment when sprayed in the field.According to the international union of pure and applied chemistry(IUPAC)report,thiamethoxam moiety in soil has a half-life of15.5 d,but in thiamethoxam moiety in the aquatic environment can be stable,belongs to the difficult to degradation of pesticides,and new neonicotinoid potion strong leaching ability,easy to follow precipitation into the natural water cycle,environment pose a threat to aquatic organisms,for fish of non-target organisms,such as a potential threat.In order to further explore the toxic effect of thiacloprid on aquatic organisms and provide theoretical basis for the popularization and use of thiacloprid in agricultural production,this study conducted experiments on model biological zebrafish by semi-static method.The acute toxicity of 20 mg/L,24 mg/L,28.8 mg/L,34.56 mg/L,41.47 mg/L,49.77mg/L to zebrafish larvae and adults and 0.3 mg/L,1 mg/L,3 mg/L and 9 mg/L weredetermined after exposure for 24 h,48h,72 h and 96 hReactive oxygen species(ROS)content,superoxidase(SOD)activity,malondialdehyde(MDA)content,glutathione s-transferase(GST)activity and DNA damage of liver cells of adult zebrafish after mg/L exposure for 7d,14 d,21d and 28 d were used to evaluate the toxicity of thiamethyline to aquatic organisms.The results showed that the timidacloprid showed low toxicity to both larvae and adults of zebrafish,and had certain influence on the physiological indexes of toxicity determination in liver of adult zebrafish.The main research results included the following aspects:1.Thiamethoxam moiety for model zebrafish larvae and adult salmon in the acute toxicity test,zebrafish larvae and adult salmon treated with different concentrations of thiamethoxam Lin,the following symptoms: after treated with high concentration,zebrafish larvae of the heart to slow or even death,and as you progress through the test,exposed to thiamethoxam moiety of zebrafish larvae appeared to slow compared with control group,loss of voluntary movement ability and other characteristics;After the treatment of adult zebrafish with thiacloprid,the zebrafish in the high-concentration treatment group showed the toxic symptoms such as fish body imbalance and rollaway,sluggish activity,sunken bottom and blush color for 3h,and with the progress of the experiment,most of the poisoned fish showed the phenomenon of sluggish movement and lethargy.The poisoning symptoms of zebrafish in the low concentration group appeared later and were not obvious.The results showed that the lethal concentrations of timidacloprid to adult and larva of zebrafish at 96 h were as follows:adult(57.80 mg/L),larva(28.01 mg/L).2.Reactive oxygen species(ROS)content: the ROS content in zebrafish liver showed a rising trend when the timidacloprid was exposed for 7d,14 d,21d and 28 d,and the higher the timidacloprid concentration was,the higher the ROS content was.3.Malondialdehyde(MDA)content:At 7d,MDA content in the exposed treatment group increased significantly at high concentrations(3 mg/L,9 mg/L),while there was no significant difference between the low-concentration group and the control group.At 14 d,21d,and 28 d,MDA content in the exposed treatment group showed an increasing trend compared with that in the control group,and the higher the concentration of thiacloprid was,the higher the content of reactive oxygen species(ROS)was.4.Antioxidant enzyme activity: the effect of exposure treatment of superoxide dismutase(SOD)at different concentrations on SOD activity at 7d and 14 d was basically promoting.At21 d,the low concentration(0.3 mg/L,1 mg/L)group of thiacloprid exposure treatment showed a promoting effect on superoxide enzyme(SOD)activity.The high concentration group(3 mg/L,9 mg/L)showed inhibitory effect.The activity of superoxide enzyme(SOD)was inhibited by exposure to thiacloprid at each concentration for 28 days.The activity changes of peroxidase POD and catalase CAT were basically the same as those of SOD,both of which were firstly activated and then inhibited.However,POD was inhibited earlier under the same concentration treatment.5.Glutathione s-transferase(GST)activity:Compared with the control group,the activity of glutathione s-transferase(GST)in zebrafish liver was significantly inhibited at 7d,14 d,21d and 28 d.6,DNA damage of zebrafish liver: zebrafish liver cells treated with concentration to thiamethoxam moiety 7 d,14 d and 21 d and 28 d after the OTM values are increased with the concentration of thiamethoxam moiety processing and increased significantly,with significant difference between two group,four days of the test results are presented to thiamethoxam moiety obvious positive correlation between concentration and OTM value effect,so it can explain thiamethoxam moiety with zebrafish liver cells possess a dose-effect relationship between DNA damage degree.