Comparative Sublethal Toxicity of Three Neonicotinoids in Red-Winged Blackbirds

Area of Science:

• Environmental Toxicology
• Avian Ecology
• Pesticide Impact Studies

Background:

• Seed-eating birds in agricultural areas face neonicotinoid exposure via treated seeds.
• Sublethal neonicotinoid exposure in birds is known to reduce body mass and fat stores, but the mechanism remains unclear.

Purpose of the Study:

• To investigate the mechanism by which neonicotinoids reduce body mass in birds, hypothesizing appetite suppression over increased energy expenditure.
• To assess the effects of acute exposure to imidacloprid, thiamethoxam, and clothianidin on red-winged blackbirds.

Main Methods:

• Red-winged blackbirds were orally dosed with imidacloprid, thiamethoxam, or clothianidin at realistic concentrations.
• Birds were also subjected to moderate or high food restriction for comparison.
• Body mass, food consumption, and biochemical markers of energetic state were monitored over 3 days.

Main Results:

• Imidacloprid exposure led to neurotoxic symptoms, reduced food intake, and persistent body mass loss, mirroring effects of food restriction.
• Clothianidin and thiamethoxam altered food consumption and biochemical markers but without overt neurotoxicity.
• Appetite suppression was identified as the primary driver of body mass reduction in imidacloprid-exposed birds.

Conclusions:

• Acute neonicotinoid exposure significantly impacts appetite, body mass, and energetic status in seed-eating songbirds.
• Neonicotinoids may pose a threat to the survival of avian populations through behavioral and physiological disruption.
• Understanding these mechanisms is crucial for assessing the ecological risks of neonicotinoid pesticides.