2025 Midwest Fish & Wildlife Conference

AUTHORS: Thomas J. Benson, Illinois Natural History Survey, Prairie Research Institute, University of Illinois Urbana-Champaign; Tara A. Beveroth, Illinois Natural History Survey, Prairie Research Institute, University of Illinois Urbana-Champaign; Claire A. Johnson, Illinois Natural History Survey, Prairie Research Institute, University of Illinois Urbana-Champaign; Edward P. Price, Illinois Natural History Survey, Prairie Research Institute, University of Illinois Urbana-Champaign; Timothy A. Rye, Illinois Natural History Survey, Prairie Research Institute, University of Illinois Urbana-Champaign; Emily J. Lain, Illinois Natural History Survey, Prairie Research Institute, University of Illinois Urbana-Champaign; Brian M. Charles, Illinois Natural History Survey, Prairie Research Institute, University of Illinois Urbana-Champaign; and David N. Zaya, Illinois Natural History Survey, Prairie Research Institute, University of Illinois Urbana-Champaign

ABSTRACT: Starting in the second half of the 20th century, agricultural intensification increasingly involved the use of chemicals for pest control. The development of numerous synthetic pesticides, including herbicides, insecticides, and fungicides, led to widespread use and, in some cases, recognition of widespread non-target effects on organisms. Unfortunately, our understanding of the potential effects of these pesticides on non-target organisms generally lags behind their widespread adoption, as does our understanding of the extent to which these chemicals travel beyond the agricultural fields in which they’re applied and end up in natural areas. In 2023, we set out to examine the extent of plant damage consistent with non-target herbicide exposure as well as to quantify concentrations of pesticides from plant tissue and soil from natural areas throughout Illinois. We sampled >180 sites in Illinois 2 times during the growing season of 2023 and found at least moderate damage to plants at almost all sites, with >50% of sites having severe damage and oak species most frequently affected. We found pesticides in nearly all natural areas, with 40 different chemicals detected, primarily from plant tissues. Herbicides were found in the greatest concentrations, with Atrazine and 2,4-D most common, and Dicamba relatively rare. Later in the season, fungicides and insecticides were more commonly detected. The amount of row-crop agriculture in the surrounding kilometer predicted leaf-tissue concentrations of pesticides and severity of plant injury. The longer-term effects of this exposure and plant injury are unknown, as are the effects on insects and insectivorous birds. Given that oaks were the most frequently observed with plant damage, and the disproportionate importance of this group for caterpillars and the migrating and breeding birds that consume them, more work is needed to explore these implications.