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Environ Pollut. 2018 Jan;232:183-190. doi: 10.1016/j.envpol.2017.09.032. Epub 2017 Sep 15.

Acute toxicity, bioconcentration, elimination and antioxidant effects of fluralaner in zebrafish, Danio rerio.

Author information

1
Education Ministry Key Laboratory of Integrated Management of Crop Diseases and Pests, College of Plant Protection, Nanjing Agricultural University, Nanjing, 210095, China.
2
Environmental Chemistry and Toxicology Laboratory, Department of Environmental Science, Policy, and Management, University of California, Berkeley, CA, 94720-3112, United States.
3
Tea Research Institute, Chinese Academy of Agriculture Sciences, Hangzhou, 310008, China.
4
Jiangsu Centre for Research and Development of Medicinal Plants, Institute of Botany, Jiangsu Province and Chinese Academy of Sciences, Nanjing, 210095, China.
5
Education Ministry Key Laboratory of Integrated Management of Crop Diseases and Pests, College of Plant Protection, Nanjing Agricultural University, Nanjing, 210095, China. Electronic address: zcq@njau.edu.cn.

Abstract

Fluralaner is a novel isoxazoline insecticide which shows high insecticidal activity against parasitic, sanitary and agricultural pests, but there is little information about the effect of fluralaner on non-target organisms. This study reports the acute toxicity, bioconcentration, elimination and antioxidant response of fluralaner in zebrafish. All LC50 values of fluralaner to zebrafish were higher than 10 mg L-1 at 24, 48, 72 and 96 h. To study the bioconcentration and elimination, the zebrafish were exposed to sub-lethal concentrations of fluralaner (2.00 and 0.20 mg L-1) for 15 d and then held 6 d in clean water. The results showed medium BCF of fluralaner with values of 12.06 (48 h) and 21.34 (144 h) after exposure to 2.00 and 0.20 mg L-1 fluralaner, respectively. In the elimination process, a concentration of only 0.113 mg kg-1 was found in zebrafish on the 6th day after removal to clean water. After exposure in 2.00 mg L-1 fluralaner, the enzyme activities of SOD, CAT, and GST, GSH-PX, CarE and content of MDA were measured. Only CAT and CarE activities were significantly regulated and the others stayed at a stable level compared to the control group. Meanwhile, transcriptional expression of CYP1C2, CYP1D1, CYP11A were significantly down-regulated at 12 h exposed to 2.00 mg L-1 of fluralaner. Except CYP1D1, others CYPs were up-regulated at different time during exposure periods. Fluralaner and its formulated product (BRAVECTO®) are of low toxicity to zebrafish and are rapidly concentrated in zebrafish and eliminated after exposure in clean water. Antioxidant defense and metabolic systems were involved in the fluralaner-induced toxicity. Among them, the activities of CAT and CarE, and most mRNA expression level of CYPs showed fast response to the sub-lethal concentration of fluralaner, which could be used as a biomarker relevant to the toxicity.

KEYWORDS:

Acute toxicity; Antioxidant response; Bioconcentration; Cytochrome P450; Fluralaner; Zebrafish

PMID:
28923341
DOI:
10.1016/j.envpol.2017.09.032
[Indexed for MEDLINE]

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