Sublethal Doses of Imidacloprid Negatively Impact Health Biomarkers of Eared Doves (Zenaida auriculata)

Imidacloprid (IMI) is a widely used neonicotinoid insecticide that presents potential risks to non-target avian species. This study investigated the sublethal effects of IMI on the health of the eared dove (Zenaida auriculata), a common granivorous bird in South America. The objective was to characterize the impacts of subchronic oral exposure to IMI on behavioral, physiological, hematological, and biochemical parameters. Eighteen adult male doves (n = 18) were randomly assigned to three groups: a control group receiving water orally, and two treatment groups receiving IMI dissolved in water at doses equivalent to 1/15th (low dose, LD, 3.93 mg/kg b.m.) and 1/5th (high dose, HD, 11.8 mg/kg b.m.) of the oral LD₅₀, administered daily by gavage for 21 days. Health biomarkers measured included water intake, body mass, somatic indices, hematological profiles, and plasma biochemical parameters. Results indicated a significant decrease in body mass in the HD group of doves exposed to IMI. In this group, only an increase in the heterophil/lymphocyte ratio was observed among the hematological parameters. Biochemical parameters showed decreased lactate dehydrogenase (LDH) and increased serum butyrylcholinesterase (BuChE) activities. These findings suggest that IMI, even at sublethal doses, can trigger physiological stress responses, generate metabolic alterations, and exert neurotoxic effects in eared doves. Exposure levels in this study were below those allowed for IMI-treated seeds in Argentina, underscoring the environmental risks to wild birds. Application of sensitive health biomarkers underscores the need for further ecotoxicological research and regulatory measures to mitigate the environmental impact of neonicotinoids on birds.