LAUSR

We used domestic chickens (Gallus gallus domesticus) as a model for granivorous birds to identify methods to detect recent imidacloprid (IMI) exposure in wild birds. We conducted dosing experiments of 1%, 5%, 10%, and 20% of a reported LD50 for domestic chickens using repeated daily exposures over 7 d, at dosages equating to 1.04, 5.2, 10.4, and 20.8 mg/kg/d. We examined parent compound and metabolites in serial collections of feces and blood during exposures and for 15 d after exposures. We also collected liver, kidney, brain, muscle, and spleen at the experiment end. Mean concentrations of parent compound 15 d post-exposure were highest in the feces and brain, then liver, muscle, spleen, and kidney, but mean concentrations of metabolites 5-OH-IMI and IMI-olefin were highest in feces, then liver, spleen, muscle, kidney, then brain. Imidacloprid was rapidly cleared from blood, with only one individual in any dose group having detectable concentrations after 48 h. In contrast, fecal pellets had the highest frequency of IMI detection after 15 d. Concentrations of metabolites were higher than parent compound at all sampling times examined, but provided no information about time since exposure. Feces may provide a reliable non-lethal method for detection of recent IMI exposure in wild birds. Additional work is needed to disentangle exposure dose concentration and time since exposure in field-collected samples. This article is protected by copyright. All rights reserved.