Chronic toxicity of tetraconazole and penconazole to Daphnia magna: Insights of growth, reproduction and gene expression changes

Tetraconazole and penconazole are widely used fungicides belonging to the conazole family. Due to the increasing use of these fungicides, their concentrations in aquatic environments are increasing and imply a serious threat to aquatic organisms. However, no studies have investigated the effects of tetraconazole and penconazole on aquatic invertebrates. This study examined for the first time, changes in growth, reproduction, and survival rate as well as changes in the expression of genes related to detoxification (HR96, P-GP, CYP360A8, GST) and reproduction (CUT, CYP314, DMRT, VTG) in D. magna after exposed to different tetraconazole and penconazole concentrations for 21 days. The 48-h EC50 value was 12.35 μg/L for tetraconazole and 326.8 μg/L for penconazole. Chronic toxicity results showed that exposure to varying concentrations of tetraconazole and penconazole decreased body length, total offspring per female, molting frequency, heartbeat rate per minute, and survival rate, and increased day to the first brood in D. magna. The expression of genes related to detoxification and reproduction changed depending on the fungicide type and concentration. In general, transcription of genes related to detoxification was more affected by fungicides. The results revealed that tetraconazole and penconazole caused toxicity in D. magna by inhibiting growth and reproduction and affecting detoxification pathways similarly.