DOI: 10.5061/dryad.wm37pvmj7
title: Ecological impacts of pesticide seed treatments on arthropod communities in a grain crop rotation

description: 1. While many studies have investigated non-target impacts of
 neonicotinoid seed treatments (NSTs), they usually take place within a
 single crop and focus on specific pest or beneficial arthropod taxa. 2. We
 compared the impacts of three seed treatments to an untreated control:
 imidacloprid + fungicide products, thiamethoxam + fungicide products, and
 fungicide products alone in a three-year crop rotation of full-season
 soybean, winter wheat, double-cropped soybean and maize. Specifically, we
 quantified neonicotinoid residues in the soil and in weedy winter annual
 flower buds and examined treatment impacts on soil and foliar arthropod
 communities as well as on plant growth and yield. 3. Unquantifiably low
 amounts of insecticide were found in winter annual flowers of one species
 in one site year, which did not correspond with our treatments. Although
 low levels of insecticide residues were present in the soil, residues were
 not persistent. Residues were highest in the final year of the study,
 suggesting some accumulation. 4. We observed variable impacts of NSTs on
 the arthropod community; principle response curve and redundancy analyses
 exhibited occasional treatment effects, with treatments impacting the
 abundance of various taxa, including predators and parasitoids. Overall,
 foliar taxa were impacted more than soil taxa, and the fungicides
 occasionally effected communities and individual taxa. 5. Pest pressure
 was low throughout the study, and although pest numbers were reduced by
 the insecticides, corresponding increases in yield were not observed. 6.
 Synthesis and applications. Pesticide seed treatments can impact arthropod
 taxa, including important natural enemies even when environmental
 persistence and active ingredient concentrations are low. The foliar
 community in winter wheat showed that in some cases, these impacts can
 last for several months after planting. Given the low pest pressure and
 lack of yield improvement in full-season and double-cropped soybean,
 winter wheat, and maize, we did not observe benefits that could justify
 the risks associated with neonicotinoid seed treatment (NST) use. Our
 results suggest that NSTs are not warranted in Maryland grain production,
 outside of specific instances of high pest pressure.
description: This data was collected as part of a three-year field study
 conducted in full-season soybean (2015), winter wheat (2015-2016),
 double-cropped soybean (2016) and maize (2017). We collected arthropod
 data through pitfall traps, litter extraction, sticky cards, sweep netting
 (only in soybean) and visual scouting, and agronomic data consisting of
 stand density, plant height, yield, NDVI (only in wheat) and tiller
 density (only in wheat). Detailed descriptions of how each type of data
 was collected and processed are included within the metadata tabs of
 individual data files. 
description: All information needed to use this dataset is included within the
 metadata tabs of individuals files. Raw arthropod data for pitfall traps,
 litter extraction, sticky cards and sweep net samples was collected using
 a system of plot numbers and numeric taxon codes, both of which are
 detailed within the individual data files. The raw arthropod data was
 formatted for analysis using SAS 9.4 (SAS Institute Inc., Cary, NC, USA).
 The code used to format the data is included in a separate file titled
 'SAS Code for Formatting Raw Arthropod Data' along with detailed
 notes on how to use it for the different data sets. The formatted data
 sets are also included as separate files.