Acute and chronic effects of thifluzamide on Daphnia magna

Abstract

Thifluzamide is a thiazole carboxanilide fungicide used to control a wide range of basidiomycete diseases on maize, potatoes,rice, and other crops. Although this fungicide is found in aquatic environments, there is no information about its acute and chronictoxicity on aquatic invertebrates. In the present study, to investigate acute and chronic toxicity of thifluzamide, daphnids were exposedto 1.25, 1.5, 2, and 2.5 mg/L thifluzamide for 48 h and 21 days, respectively. The expression of four oxidative stress-related genes(CAT, GCLC, GST, and GPX) and life-history parameters such as days to the first brood, days to the first egg production, and moltingfrequency were measured. The results showed that exposure to thifluzamide for 48 h significantly induced the expression of oxidativestress-related genes in D. magna. A dose-dependent relationship was obtained for mRNA levels of CAT and GST. In the 21-day chronictoxicity test, a concentration-dependent decrease was observed for the number of neonates per Daphnia, the number of broods perfemale, and molting frequency. Additionally, the first brood day and the first egg production day were significantly (P < 0.05) delayed ina dose-dependent manner. The results of this study indicate that the harmful effects of thifluzamide on aquatic invertebrates cannot beignored and further investigation is needed.