Imidacloprid seed coating poses a risk of acute toxicity to small farmland birds: A weight-of-evidence analysis using data from the grayish baywing Agelaioides badius

• Autores: Poliserpi, Maria Belen; Cristos, Diego Sebastian; Brodeur, Celine Marie
• Año de publicación: 2020
• Idioma: inglés
• Tipo de recurso: artículo
• Fuente: Science of The Total Environment : 142957 (Available online 14 October 2020)
• Materia: Imidacloprid; Toxicidad; Pájaros; Agricultura; Contaminación; Evaluación de Riesgos; Toxicity; Birds; Agriculture; Contamination; Risk Assessment; Agelaioides badius
• Institución: Instituto Nacional de Tecnología Agropecuaria

The aim of this study was to estimate the risk posed by imidacloprid (IMI) seed coating to passerine birds of the Pampa Region of Argentina using data specifically generated with the grayish baywing (Agelaioides badius). Median lethal dose (LD50) of the IMI-based formulation tested was 57.11 mg IMI/kg body weight (bw), with intoxication signs starting from 20.6 mg IMI/kg bw. The feed intake rate (FIR) was estimated experimentally as 4.895 g/day per bird, representing 12.43% of bw. It was calculated that the ingestion of 7–10% of the FIR as treated seeds would be enough to achieve the LD50 for sorghum, corn, sunflower, and alfalfa, whereas consumption of 31 and 54% of FIR was necessary for oat and wheat, respectively. Based on spill data values available in the literature, it was calculated that, for most crops, a baywing would have to forage an area of field corresponding to less than 60 m2 to obtain the number of seeds required to reach the LD50. It was also shown that this number of seeds is coherent with the amount of seeds ingested in a bout. In a pilot study, all grayish baywings fed with millet seeds treated with 3 g IMI/kg died within three to five days of exposure. In Tier I risk assessment, the trigger value was achieved for all crops except soybean and a weight-of-evidence risk assessment was performed. All lines of evidence examined are consistent with the view that grayish baywings, and probably other small farmland birds, are exposed to a risk of acute toxicity and mortality under both worst-case and mixed-ration exposure scenarios. The possible impacts on bird species calls for an urgent reconsideration of IMI seed coating practices currently approved in the Pampa Region of Argentina and the various parts of the world where this practice is still in use.
Instituto de Recursos Biológicos
Fil: Poliserpi, María Belén. Instituto Nacional de Tecnología Agropecuaria (INTA). Instituto de Recursos Biológicos; Argentina.
Fil: Cristos, Diego. Instituto Nacional de Tecnología Agropecuaria (INTA). Instituto de Tecnología de Alimentos; Argentina.
Fil: Brodeur, Celine Marie Julie. Instituto Nacional de Tecnología Agropecuaria (INTA). Instituto de Recursos Biológicos; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina.