Toxic Effects Of Three Succinate Dehydrogenase Inhibitor Fungicides On Zebrafish

The importance of pesticides for social development is obvious.In recent years,fungicides,especially novel succinate dehydrogenase inhibitor?SDHI?fungicides,have developed rapidly.After long-term use,residues of fungicides may migrate into the water environment.It is necessary to study the potential risks of fungicides to aquatic organisms.SDHI fungicides are potentially toxic to fish.However,information on the toxic effects and mechanisms of benzovindiflupyr,isopyrazam and sedaxane to aquatic organisms is still limited.Against this background,present work use the embryo and adult zebrafish as model organisms to carry out the aquatic biological toxicity experiments of the SDHI fungicides-benzovindiflupyr,isopyrazam and sedaxane.This work aims to explore the toxic effects and mechanisms of these three SDHI fungicides on zebrafish.1.Through a 96-hour acute test,it was revealed that these three fungicides caused morphological changes,hatching failure and mortality in zebrafish embryos.The 96 h-EC₅₀ values of benzovindiflupyr,isopyrazam and sedaxane against embryonic hatching inhibition were 0.039,0.21 and 3.41 mg/L,respectively.Besides,the 96 h-LC₅₀ values of benzovindiflupyr,isopyrazam and sedaxane to embryos were0.041,0.24 and 3.69 mg/L,respectively.2.Through a series of acute developmental toxicity tests,it was revealed that benzotrifenazole,pyrazolamide and fluoxazole affect various aspects of zebrafish embryo development.???They interfered with the expression of the embryo development-related genes bmp2b,gh1,ghra and igf1,resulting in a shorter body length of the larvae.???They affected the larval ATP,NO,NOS,CaN,AChE and EPI,as well as the embryonic spontaneous movement and the larval free movement.???They interfered with the expression of cardiac development-related genes cyp26a1and myh7,and disrupted heart rate.???They interfered with the expression of apoptosis-related genes apaf1,baxa,bbc3,bcl2a,casp3a,caspb and tp53,and induced apoptosis.???They interfered with the antioxidant biomarkers,CAT,GST,POD,SOD and GSH,and caused an increase in the larval MDA and ROS.???They inhibited larval SDH activity.???They interfered with the contents of T4 and T3 of larvae.???They interfered with the expression of the larval innate immune-related genes ccl34a.4,cxcl18b,ifnphi1,il6,il6r,loxa,nos2a and tnfa.3.The acute toxicity of these three fungicides to adult fish was investigated by an adult zebrafish 96-hour acute test.Besides,the effects of acute exposure on oxidative stress in adult fish were investigated by measuring oxidative stress-related indicators after exposure to adult zebrafish for 7 days.???Acute exposure has impacted on the morphology and movement of adult fish.The 96-hour median lethal concentration values for adult zebrafish of benzovindiflupyr,isopyrazam and sedaxane were 0.065,0.33 and 2.60 mg/L,respectively.???The 7-day adult zebrafish experiments show interfered with the antioxidant markers,CAT,GST,POD,SOD and GSH,and an increase in MDA.4.The chronic effects of these three fungicides on females were explored by chronic exposure to adult female zebrafish for 30 days.The 30 days exposure of benzovindiflupyr,isopyrazam and sedaxane caused effects on the oxidative stress,endocrine,nervous system,energy metabolism and intestinal tissue morphology of adult female zebrafish.???They inhibited the activity of the antioxidant markers,CAT,GST,POD,SOD and GSH,and caused an increase in MDA.???They leaded to an increase in the T4 content and a decrease in the T3 content.???They inhibited the T content and E2 content.???They induced the NO,NOS,CaN and EPI,and inhibited the CaN and AChE activity.???They inhibited the SDH activity.???They caused damage to the intestinal villi.In summary,the SDHI fungicides benzovindiflupyr,isopyrazam and sedaxane showed toxicity to both embryo and adult zebrafish.In this paper,their toxicity mainly manifests as acute lethality,developmental inhibition,cause oxidative stress,neurotoxicity,endocrine disruption and intestinal injury.Therefore,the potential toxicity of SDHI fungicides to aquatic organisms may be manifested by a variety of effects.More studies should be performed for expanding knowledges of potential impact of these fungicides on aquatic environment.