Effects of two strobilurins (azoxystrobin and picoxystrobin) on embryonic development and enzyme activities in juveniles and adult fish livers of zebrafish (Danio rerio)

Azoxystrobin and picoxystrobin are two primary strobilurin fungicides used worldwide. This study was conducted to test their effects on embryonic development and the activity of several Enzyme in the zebrafish (Danio rerio). After fish eggs were separately exposed to azoxystrobin and picoxystrobin from 24 to 144 h post fertilization (hpf), the mortality, hatching, and teratogenetic rates were measured. Additionally, effects of azoxystrobin and picoxystrobin on activities of three important antioxidant Enzymes [catalase (CAT), superoxide dismutase (SOD) and peroxidase (POD)] and two primary detoxification Enzymes [Carboxylesterase (CarE) and Glutathione S-transferase (GST)] and malondialdehyde (MDA) content in zebrafish larvae (96 h) and livers of adult zebrafish of both sexes were also assessed for potential toxicity mechanisms. Based on the embryonic development test results, the mortality, hatching, and teratogenetic rates of eggs treated with azoxystrobin and picoxystrobin all showed significant dose- and time-dependent effects, and the 144-h LC₅₀ values of azoxystrobin and picoxystrobin were 1174.9 and 213.8 μg L^-1, respectively. In the larval zebrafish (96 h) test, activities of CAT, POD, CarE, and GST and MDA content in azoxystrobin and picoxystrobin-treated zebrafish larvae increased significantly with concentrations of the pesticides compared with those in the control. We further revealed that azoxystrobin and picoxystrobin exposure both caused significant oxidative stress in adult fish livers and the changes differed between the sexes. Our results indicated that picoxystrobin led to higher embryonic development toxicity and oxidative stress than azoxystrobin in zebrafish and the male zebrafish liver had stronger ability to detoxify than that of the females.