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Ecological impacts of pesticide seed treatments on arthropod communities in a grain crop rotation

Citation

Dubey, Aditi; Lewis, Margaret; Dively, Galen; Hamby, Kelly (2020), Ecological impacts of pesticide seed treatments on arthropod communities in a grain crop rotation, Dryad, Dataset, https://doi.org/10.5061/dryad.wm37pvmj7

Abstract

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.

Methods

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. 

Usage Notes

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.

Funding

U.S. Department of Agriculture National Institute of Food and Agriculture (Hatch/Multistate funds), Award: project no. MD-ENTM648 8887/project accession no. 1009567 and project no. MD-ENTO-9589/project accession no. 649 1012455

U.S. Department of Agriculture National Institute of Food and Agriculture (North East SARE program)

U.S. Department of Agriculture National Institute of Food and Agriculture (North East SARE program), Award: sub-award number 651 GNE16- 11B-29994

U.S. Department of Agriculture National Institute of Food and Agriculture (Crop Protection and Pest Management Program)

U.S. Department of Agriculture National Institute of Food and Agriculture (Crop Protection and Pest Management Program), Award: grant no. 2017-70006-27171/project accession no. 655 1013913

Maryland Grain Producers Utilization Board

Maryland Soybean Board