Even though farmers use precise methods for sowing row crop seeds, small numbers may remain available on the soil surface. Thus, bird species foraging in agricultural fields could be exposed to unincorporated seeds treated with a pesticide. EPA’s T-REX model for birds potentially consuming treated speeds does not account for seeds incorporated at planting, or for untreated waste grains present on untilled fields. Therefore, we developed the higher tier Seed Pesticide Avian Risk Assessment Model (SeedPARAM) for birds potentially exposed to treated seeds. The probabilistic model has an hourly time step and estimates acute and chronic risk to each of 20 birds per species on each of 1000 fields. Currently, the model includes eight bird species that forage for seeds in corn and soybean fields. Three routes of exposure are included in the model: consumption of seeds on the soil surface, consumption of below ground seeds obtained by uprooting young shoots, and consumption of young shoots. For each simulated bird, values are randomly selected for the major input variables (e.g., metabolic rate, proportion diet from treated fields) to estimate exposure. The simulation is repeated for 20 birds on each treated field. The model then moves to the next field. Fields differ with regard to pesticide dissipation rate, attractiveness to foraging birds, and waste grain availability. The number of waste grains on the soil surface affects the probability that a bird will consume a treated seed. The outer loop continues for 1000 fields. The model can either estimate probabilities of exceeding acute and chronic benchmarks or generate risk curves that define the relationship between cumulative probability and magnitude of effect. In this presentation, we illustrate SeedPARAM with a case study and discuss possible refinements for future versions of the model (e.g., considering foraging range, body size limitations for consuming large seeds).

Probabilistic model for assessing risk to bird species potentially exposed to seed treatment pesticides

256th National Meeting (2018)

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.