Studies On The Toxicity Of Different Formulations Tebuconazole To Two Aquatic Organisms

Tebuconazole is a triazole systemic fungicide with high activity,wide spectrum of sterilization and long-lasting effect.It is one of the most commonly used and widely used fungicides in agricultural production.Tebuconazole has been registered for the control of rice diseases,and may enter water bodies such as rivers and lakes during use,which has an impact on the water environment.Tebuconazole is available in a variety of registered dosage forms.The toxic effects of a single tebuconazole formulation on one or several aquatic organisms have been reported,and the differences in toxicity of different tebuconazole formulations to different aquatic organisms are still lacking in a comprehensive and systematic comparison.In this study,Daphnia magna and Brachydanio rerio were used as model organisms.The four common preparations of tebuconazole and the acute and chronic toxicity of the technical material to D.magna and B.rerio were compared.Preliminary analyzes of the causes of differences in toxicity of different formulations tebuconazole to aquatic organisms,and theoretical guidance was provided for selecting suitable dosage forms in the field to reduce the side effects of pesticides.The main results are the following:1.The acute toxicity of technical material?TC?and four preparations of tebuconazole to Daphnia magna were determined by static method.The results showed that,the 48h median effective dose(EC₅₀)of 95%tebuconazole TC,50%tebuconazole SC,250g/L tebuconazole EW and 80%Tebuconazole WP,85%tebuconazole WG for D.magna were8.20,2.442,2.12,5.87 and 2.689 mg a.i./L,respectively.According to“Experimental Guideline for Environmental Safety Evaluation of Chemical Pesticides”,the toxicities of four tebuconazole preparations to acute toxicity of D.magna were medium toxicity.So the toxicities of different formulations of tebuconazole to D.magna were different.TC had the lowest toxicity in the test.And among four preparations,WP has the lowest toxicity.2.The chronic toxicity of tebuconazole and four tebuconazole preparations to D.magna were determined by semi-static method.The results showed that,as the concentration increased,tebuconazole and its four formulations significantly reduced the average number and number of calves per fetus.The LOEC values of the tebuconazole suspending agent,tebuconazole aqueous emulsion and tebuconazole water-dispersible granules on the reproductive index of large cockroaches were 2.5×10^-2,1.25×10^-22 and2.5×10^-22 mg a.i./L.Compared with the tebuconazole TC,and the LOEC value of the wettable powder and the original drug was 0.05 mg a.i./L,and the toxicity difference was not obvious.Compared with the chronic toxicity of large cockroaches,tebuconazole WP has the largest LOEC value for large cockroaches,and its chronic toxicity to large cockroaches was the lowest compared with the other three formulations.3.The acute toxicity of tebuconazole and four tebuconazole preparations to Zebrafish embryo were determined by semi-static method.The results showed that,the 96h median lethal dose(LC₅₀)of 95%tebuconazole TC,50%tebuconazole SC,250g/L tebuconazole EW,80%Tebuconazole WP and 85%tebuconazole WG for Zebrafish embryo were 3.116,2.439,2.094,2.90 and 2.464 mg a.i./L,respectively.The acute toxicity of tebuconazole to Zebrafish embryo increased with the prolongation of the test time.The toxicity of the different formulations tebuconazole was not significant,and the toxicity of the EW was relatively high.4.The acute toxicity of tebuconazole and four tebuconazole preparations to D.rerio was determined by semi-static method.The results showed that,the 96h median lethal dose(LC₅₀)of 95%tebuconazole TC,50%tebuconazole SC,250g/L tebuconazole EW,80%Tebuconazole WP and 85%tebuconazole WG for D.rerio were 7.779,5.965,4.974,6.754and 6.64 mg a.i./L,respectively.The acute toxicity of tebuconazole to D.rerio increased with the prolongation of the test time,but the acute toxicity increased slowly within 96hours.Among them,the LC₅₀0 of 80%tebuconazole WP were reached the peak value after72 hours.According to“Experimental Guideline for Environmental Safety Evaluation of Chemical Pesticides”,the toxicities of four tebuconazole preparations to acute toxicity of D.rerio was medium toxicity,and the securities of different formulations of tebuconazole to acute toxicity of D.rerio was different.WP had the lowest toxicity and EW has the highest toxicity.