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Histopathology of zebra finches (Taeniopygia guttata) orally exposed to clothianidin (ver. 2.0, October 2019)

November 4, 2019

This dataset reports select histopathological changes in liver, kidney, gonad, spleen, brain, heart, skeletal muscle, lung, or adrenal gland of zebra finches exposed to 15mg/kg, 18mg/kg, 30mg/kg, 60mg/kg, 75mg/kg, 125mg/kg, or 250mg/kg clothianidin (CTD) (with controls) by gavage, in water, or on millet seed either as a single dose or for 7 days. The goal of the project is to develop a subacute neonicotinoid toxicity model using zebra finches as a model passerine. We have completed two acute toxicity trials using CTD insecticide. Based on these studies, we estimate the no observable effect level (NOAEL) and the lowest observable effect level (LOAEL) for CTD in zebra finches to be 15 and 30 mg/kg body weight, respectively, and the concentration producing a toxic effect in 50% of treated birds (EC50) to be approximately 150mg/kg. We next exposed birds for 7 days to CTD in drinking water at nominal doses of 40, 20, 4, and 0mg/kg (cumulative 240, 140, 28, and 0mg/kg CTD). Clinical signs of toxicity were not observed in any bird. Lastly, birds were gavaged daily for 7 days with 18mg/kg body weight CTD dissolved in acetone and mixed with vegetable oil. Clinical signs of toxicity were observed beginning after the fourth exposure day and were similar to signs observed in acute (125 mg/kg) CTD dosing. In order to further refine our model, we re-tested CTD treatment via drinking water (at a higher dose of 60mg/kg), exposed birds to 7 days of CTD coated millet seed (15mg/kg, 30mg/kg and 60mg/kg), and extend the follow-up time following an acute exposure to 21 days. Tissues were scanned on at least 10x objective and lesions potentially associated with neonicotinoid exposure were scored on a severity scale of 0-3 (0: absent; 1: mild; 2: moderate; 3: severe). Despite clinical signs of toxicity, there were no consistent microscopic lesions of exposure at the dose levels examined. First release: April 10, 2018 Revised: October 31, 2019 (ver. 2.0)