Browsing by Subject "Neonicotinoids"

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    Data Supporting Neonicotinoid Insecticides in Surface Water, Groundwater, and Wastewater across Land Use Gradients and Potential Effects
    (2020-07-23) Berens, Matthew J; Capel, Paul D; Arnold, William A; arnol032@umn.edu; Arnold, William A; University of Minnesota Department of Civil, Environmental, and Geo- Engineering
    Neonicotinoid insecticides are known to cause adverse effects on non-target organisms, but more information about their occurrence in surface and groundwater is needed across a range of land use. In this study, water samples from across the state of Minnesota, U.S., were analyzed to determine the variability in spatiotemporal neonicotinoid concentrations and their relations to land use, hydrogeologic condition, and to assess potential effects on aquatic life. Sixty-five sites, representing rivers and streams, lakes, groundwater, and treated wastewater were monitored, via collection of 157 water samples. Results showed that total neonicotinoid concentrations were the highest in agricultural watersheds (median = 12 ng/L) followed by urban (2.9 ng/L) and undeveloped watersheds (1.9 ng/L). Clothianidin was most frequently detected in agricultural areas, and imidacloprid was most frequently detected in urban waters. The seasonal trend of neonicotinoid concentrations in rivers, streams, and lakes showed that their highest concentrations coincided with spring planting and elevated streamflow conditions. Consistently low neonicotinoid concentrations were found in shallow groundwater in agricultural regions. Treated municipal wastewater had the highest overall concentrations, however, neonicotinoid loads from rivers and streams (median = 4100 mg/d) were greater than in treated wastewater 700 mg/d). No concentrations exceeded aquatic-life benchmarks, but increasing use and sublethal effects create potential risks, such as toxicity and disrupted development of aquatic insects, to natural and engineered waters. This the first study of its size to document the occurrence of neonicotinoid insecticides in Minnesota and is critical to better understanding the drivers of widescale environmental contamination by neonicotinoids where urban, agricultural, and undeveloped lands are present.
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    Evaluation of Neurobehavioral Abnormalities and Immunotoxicity after Oral Imidacloprid Exposure in Domestic Chickens (Gallus gallus domesticus)
    (2019-05) Franzen-Klein, Dana
    Neonicotinoid pesticides may have negative effects on non-target species at environmentally plausible exposure doses. The objective of the present study was to quantify neurobehavioral abnormalities and immunotoxicity due to oral imidacloprid exposure in birds. Domestic white leghorn chickens (Gallus gallus domesticus; n=120) were exposed to imidacloprid by gavage once daily for 7 consecutive days at 0, 0.03, 0.34, 3.42, 10.25, and 15.50 mg/kg. The severity and duration of neurobehavioral abnormalities were recorded, and immune function was assessed with 7 standard functional assays. Immunotoxicity was not detected. Temporary neurobehavioral abnormalities were observed in a dose-dependent manner, including generalized whole-body muscle tremors, ataxia, and depressed mentation ranging from mild depression to a complete lack of response to external stimulation. The effect dose value for the presence of any neurobehavioral abnormalities in 50% of the test group (ED50) was 4.63 mg/kg/day. The ED50 for an adjusted score that included both the severity and duration of neurobehavioral abnormalities was 11.27 mg/kg/day. The no observed adverse effect level (NOAEL) and lowest observed effect level (LOEL) were 3.42 mg/kg/day, and the lowest observed adverse effect level (LOAEL) was 10.25 mg/kg/day. While immunotoxicity was not demonstrated in the present study, it cannot be ruled out. The observed neurobehavioral abnormalities were severe at the higher doses and may impair survival of free-living gallinaceous birds.
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    Neonicotinoid Hydrolysis and Photolysis: Rates and Residual Toxicity
    (2018-05) Todey, Stephen
    Neonicotinoid insecticides are currently the most widely used class of insecticides worldwide, accounting for 25% of total insecticide use. They are registered in 120 countries for use on more than 140 crops. Concern has grown, however, over their widespread detection in global surface waters, soil, finished drinking water, and wastewater, and for their potential role in colony collapse disorder in honey bees. This work set out to examine hydrolysis and photolysis reaction rates of neonicotinoids, as well as to identify reaction products and determine the toxicity of the reaction products on mosquitoes. Hydrolysis rates were tested between pH 4 and pH 10. Reaction rates were pseudo-first order and highly pH dependent. Calculated half-lives ranged from >1000 days to 10 days. Divalent metal ions (Cu2+, Ni2+, Zn2+) and minerals (kaolinite, goethite, TiO2) were found to have little to no effect on neonicotinoid hydrolysis. Experiments from pH 4 to pH 10 revealed a non-elementary rate law for neonicotinoid degradation, with the hydroxide concentration being raised to a power of 0.55 ± 0.09. Nitenpyram, imidacloprid, thiamethoxam, and clothianidin were found to undergo direct photolysis, with quantum yields of 0.025 ± 0.001, 0.0119 ± 0.0001, 0.0167 ± 0.0002, and 0.0133 ± 0.0001, respectively. Acetamiprid degraded very slowly via direct photolysis, but was found to undergo indirect photolysis due to reaction with OH∙ with a bimolecular rate constant of 1.7 ± 0.2×109 M-1 s-1. Reaction products were identified for all reactions, with the urea derivative as the most commonly detected product. Toxicity experiments on mosquitoes indicate no residual toxicity from hydrolysis or photolysis products, which may be expected given the removal of the pharmacophore during reactions. While abiotic reaction products were found to be non-toxic, results from experimental work indicates long environmental half-lives for the tested neonicotinoids, which may help to explain their observed persistence in environmental matrices.