The Toxic Effects Of Omethoate On Misgurnus Anguillicadatus

Omethoate,also known as folimat,has very strong contact poisoning on crop pests and mites,is the world widely used broad-spectrum organophosphorus insecticide and acaricide,mainly used for prevention and control of pests such as aphids and net tsubaki which exist in crops like apple and grape.With the increasing awareness of the hazards of pesticide pollution,the research on pesticide pollution monitoring methods constantly goes deeper,loach as biomarker has been widely used in the monitoring of environmental pollution.This study used enzyme detection method and microscopic method,to investigate the acute toxicity effect,physiological toxicity effect,vitellogenin content,micronucleus effect of erythrocytes,and the toxic effects of the gill and liver tissue of Omethoate on loach.The use of Omethoate can provide theoretical support and scientific basis for the monitoring,evaluation and treatment of water pollution.The main results are as follows:1.The acute toxicity effect of Omethoate on loachUsing single factor acute toxicity to do hydrostatic test for 96 h,the results showed that the LC50 of Omethoate on loach 24,48,72,96 h,respectively 76.91,51.17,46.03,35.89 mg·L-1,the SC of Omethoate on loach is 6.8 mg·L-1,belonged to high toxic levels of water pollutants.2.The physiological toxicity effect of Omethoate on loachWith antioxidant enzymes(SOD,CAT)and transaminase(GPT,GOT)activity changes indicate physiological toxic effects.Omethoate on loach liver SOD and CAT activity basically showed a trend of first induction then inhibition,in low(2.51 mg·L-1)treatment group the SOD and CAT activity did not change significantly,high(3.97,6.31mg·L-1)treatment group when at 7 d,the activity of SOD and CAT were significantly elevated,showed that a high concentration Omethoate had more clear effect on loach liver antioxidant enzymes.Compared with the control group,2.51 mg·L-1 treatment group activity of CAT increased significantly at 48 h,while the SOD activity did not change;at 28 d,the activity of SOD of the 6.31 mg·L-1 treatment group was about 1/2 of the control group,but the activity of CAT was reduced to about 1/4 of the control group,indicated that the effect of CAT on Omethoate was more sensitive.In the same concentration group,the activity of GPT and GOT of the Loach Liver in 0-28 d showed a decreased trend after increasing,and in 7 d or 14 d activity reached maximum.Omethoate on the transaminase activity of loach liver showed a trend of first induction then inhibition;with the increase of Omethoate concentration,the activity effect of GPT and GOT of liver of Loach were significantly enhanced.That was,the greater the concentration of Omethoate,the loach liver transaminase activity changes more significantly.3.The influnce of the vitellogenin content of Omethoate on loachThe serum VTG of loach was very sensitive to the exposure of Omethoate.Compared with the control group,the VTG content of loach was significantly increased when the low(1.58 mg·L-1)treatment group in exposed for 7 d.And with the prolongation of treatment time,the content of VTG in loach was significantly higher;in the higher concentration treatment group(6.31 mg·L-1),the content of VTG in loach was significantly much higher which indicated that in a certain concentration range,Omethoate had a time and concentration effect relationship on the content of serum VTG of loach.4.The micronucleus effect of erythrocytes of Omethoate on loachThe micronucleus rate of erythrocyte in loach were significantly increased by exposure to Omethoate.At the same treatment time,the micronucleus rate of erythrocyte in the loach were also increased with the increasing of the mass concentration of Omethoate.This trend was more obvious when the concentration of Omethoate was higher,indicating that the there is a certain dose-effect relationship between Omethoate and micronucleus rate of erythrocyte.At the same treatment concentration,the micronucleus rate of erythrocyte in loach were also increased with the increasing of the time of Omethoate treatment.It indicated that Omethoate had genetic toxicity to loach,and the toxicity increased with the increasing of the concentration of Omethoate and the prolongation of the time.5.The toxic effects of the gill and liver tissue of Omethoate stress on loachObserved the liver and gill tissues of the infected loach,when they were in the 6.31 mg·L-1 Omethoate treatment group for 14 days,the liver cells of loach were enlarged and the cytoplasm was loose and the cell gap became larger.The gills of loach were curl and produced non-tissue cavity,the structure of gill remained intact.When exposed for 28 d,the gap of the liver cells of loach significantly increased,vacuolization occurred,the nucleus deformed and the liver severely damaged,and the injury continued to accumulate over time.Many gills were serious curl or broken,even would appear the phenomenon of necrotic and shedding.