Repellency, Anorexia and Aversion by Neonicotinoid-Treated Seeds and Cotyledons on Captive Eared Doves

Farmland birds can be exposed to neonicotinoids through the ingestion of treated unburied seeds and cotyledons. The aim of this study was to evaluate repellency, anorexia, and conditioned aversion of sorghum and soybean seeds, and soybean cotyledons treated with imidacloprid, clothianidin or thiamethoxam on eared doves ( Zenaida auriculata ). Doves were fed with test food (control vs. neonicotinoid-treated sorghum, soybean or soybean cotyledons) and maintenance food for 3-5 days to study the repellency and anorexia caused by neonicotinoid-treated food, followed by a 7-day period on maintenance food to study the persistence of the anorexic effect after neonicotinoid exposure. Right after, the same doves were exposed to test food during a second period of 3-5 days to study the potential reinforcement of repellency and anorexia, and the development of conditioned aversion against the treated food. Finally, doves were fed with the test food, but without the neonicotinoid, to test the capacity of the pesticide to induce conditioned food aversion against untreated food in subsequent encounters. Intoxication signs, differences of body weight and other adverse effects were determined. With sorghum, the three neonicotinoids produced a marked repellent effect, decreasing the consumption of treated seeds by >97% compared to control birds. However, this repellency was not enough to prevent the death of 3/8 and 1/8 of the doves exposed to imidacloprid and clothianidin, respectively. Imidacloprid-treated soybeans caused a significant repellent effect, but this was not observed for the cotyledons. Anorexia was clearly observed with neonicotinoid-treated sorghum. The birds did not avoid the untreated test food after exposure to the treated ones, suggesting the importance of the color, odor or taste to cause the repellence and the conditioned aversion. In conclusion, seed avoidance caused by neonicotinoids was strong, but it failed to prevent intoxication and death on eared doves exposed to treated sorghum.