A simplified landscape-based approach for including agronomical and ecological characteristic in pesticide risk assessments for terrestrial vertebrates

Pesticides have played a crucial role in enhancing food production, although their intensive application poses significant threats to ecosystems and may cause harmful effects on non-target organisms, which are often inadequately addressed by current risk assessment methods. This study introduces a novel approach by combining data from regulatory reports with a meta-analysis to derive dose-response curves for population-relevant parameters. These curves are then integrated into a simplified population dynamics model to estimate the potential population-level effects of combined pesticide exposure on terrestrial vertebrates in Mediterranean agricultural landscapes, with a focus on vineyards in Beaujolais, France, a semi-continental region with Mediterranean influence. The model has been applied as a proof of concept to the pesticides folpet and pirimicarb, estimating the population declines linked to the expected effects on reproductive and survival rates. Folpet was found to have a more severe impact on mammal populations, while pirimicarb primarily affected birds. Additionally, the timing of pesticide application was crucial, with early-season applications of pirimicarb resulting in higher declines compared to late-season treatments. Moreover, the combined use of both pesticides resulted in effects that were not captured by single-pesticide assessments. The study highlights the benefits of landscape assessments for integrating the impacts of pesticide application schedules in real farming conditions, and offers opportunities for assessing risk mitigation approaches. Although the model is simplified and subject to certain limitations, the findings confirm the possibility for assessing the combined effects of successive applications using the information available from regulatory pesticide risk assessments. This study calls for continued research to better understand and mitigate the environmental risks associated with pesticide use.