High prevalence of the neonicotinoid clothianidin in liver and plasma samples collected from gamebirds during autumn sowing.

Since neonicotinoid insecticides were introduced to the agricultural market, evidence of the negative impacts of these systemic compounds on non-target species has accumulated. Birds are one of the largest groups of species to inhabit farmland, but the extent of neonicotinoid exposure in avian communities is poorly understood and very little is known about how any exposure may affect wild birds. Here, free-living gamebirds were used as a model group to measure the extent of avian exposure to the neonicotinoid clothianidin via seed treatment. During a typical sowing period of winter cereals treated with clothianidin, blood and liver samples were collected simultaneously from individual hunted gamebird carcasses, both pre- (n = 18) and post-sowing (n = 57) and were analysed for clothianidin via LC/MS-MS. Body weight, fat score and faecal parasite load were also quantified in the birds to ascertain whether any of these health parameters were associated with clothianidin exposure under field conditions. Clothianidin was detected in 6% of individuals sampled pre-sowing and 89% of individuals sampled post-sowing. The frequency of clothianidin detection in plasma samples and the concentration of clothianidin in liver and plasma samples decreased significantly between the first week and 2-4 weeks post-sowing. Faecal parasite load was positively associated with concentrations of clothianidin in the liver (but not plasma) of partridge species, but there was no association between clothianidin concentration and fat score or body weight, for either sample type. This study provides clear evidence that treated seed is a source of pesticide exposure for gamebirds following autumn sowing. These findings have implications for gamebirds worldwide where seed treatments are in use, and will aid the design of any future avian biomonitoring studies for agrochemical compounds.