Density of Neonicotinoid-Treated Seeds Available to Birds After Sowing Corn, Sorghum and Soybeans

ADDY ORDUNA, LAURA; DARDANELLI, SEBASTIÁN; MATEO SORIA, RAFAEL

Evento Virtual

Congreso; SETAC Latin America 14th Biennial Meeting; 2021

Society of Environmental Toxicology and Chemistry (SETAC)

Field investigations in Europe and North America have contributed to predicting the risk of poisoning by ingestion of neonicotinoid-treated seeds for birds. In South America, research on the subject is incipient. In order to complete and improve these risk assessments, field data from the region are necessary. In this sense, the objective of this work was to quantify the density of treated seeds that remain in the soil available for birds after sowing corn, sorghum, and soybeans in commercial fields located in the Argentine Espinal ecoregion. Forty-three fields (16 corn, 9 sorghum and 18 soybean) distributed in two departments of the province of Entre Ríos were evaluated through transects with equidistant points. A metal ring (0.25 m2) was placed at each point and theunburied seeds were counted. In addition, more than 30 variables related to characteristics and conditions of the field, of the crop, and of the technical aspects of sowing were surveyed. The richness and abundance of birds were estimated in 25 of the 43 fields by a 250 m transect at theheadlands and inside the field. Unburied seed samples were collected in each field to determine chemical residues. The number of seeds/m² in the headlands was significantly higher than that of the field interior. The number of seeds weighted by surface ranged between 0.022 and 2.321seeds/m² in corn, between 0.007 and 2.142 seeds/m² in sorghum, between 0.559 and 2.629 seeds/m² in the first soybeans, and between 0.079 and 5.426 seeds / m² in the second soybeans, the difference between crops being significant. Most of the surveyed variables were associated with the crop variable (corn, sorghum, first soybeans, second soybeans). The richness of seed-eating birds was higher in the headlands than in the field interior. The abundance of seed-eating birds differed between crops, being higher in corn. Neither abundance nor richness showed a clear linear relationship with the density of exposed seeds in the soil. All corn and sorghum seeds contained at least one neonicotinoid. In contrast, residues of a neonicotinoid were found only in one of the 18 soybean samples. Therefore, although soybeans were the crop with the highest density of unburied seeds, the proportion of seeds treated with neonicotinoids was much lower than in the other twocrops.