Neonicotinoid hazard assessment for birds that consume grains

ADDY-ORDUNA, LAURA M.; BRODEUR, JULIE CÉLINE; RAFAEL MATEO

Congreso; 13th biennial Meeting of Setac Latin America; 2019

Several studies have raised the possibility that neonicotinoid seed treatments could impact birds directly. In order to provide more information about the hazard and risk of neonicotinoids for birds, the acute toxicities of imidacloprid, clothianidin and thiametoxam formulations were determined on eared doves (Zenaida auriculata). Insecticides were administered by gavage to adult doves according to a standardized sequential procedure to determine median lethal doses (LD50). Formulated imidacloprid (LD50= 59 mg active ingredient, a.i./kg body weight, b.w.) was 70 times more toxic than formulated clothianidin (LD50 = 4248 mg i.a./kg b.w.) and thiametoxam (LD50 = 4366 mg a.i./kg b.w.). All deaths due to imidacloprid occurred during the first 8 hours after dosing. In contrast, thiamethoxam and clothianidin produced deaths up to almost 3 and 4 days after dosing, respectively. The main characteristic of neonicotinoid poisoning was a progressive loss of vitality and movement ("blackout"). All birds significantly reduced their food consumption during the first days post gavage, which caused body weight loss. In addition, it was calculated that a dove of average body weight of (127g) would ingest the imidacloprid LD50 by consuming 1.7 g of treated sorghum seeds, much less than the amount of sorghum that a dove is able to consume per day. The results indicate that imidacloprid can be directly dangerous when consumed through treated seeds that reach lethal doses, or indirectly by affecting vitality and movement and, thus, reducing the response of escape to possible predators. For this reason, our current studies are focused on evaluating the avoidance behavior of birds to grains treated with these neonicotinoids, and on the response to potential predators under subclinical exposures.