We present a method for calculating the Acute Insecticide Toxicity Loading (AITL) on US agricultural lands and surrounding areas and an assessment of the changes in AITL from 1992 through 2014. The AITL method accounts for the total mass of insecticides used in the US, acute toxicity to insects using honey bee contact and oral LD50 as reference values for arthropod toxicity, and the environmental persistence of the pesticides. This screening analysis shows that the types of synthetic insecticides applied to agricultural lands have fundamentally shifted over the last two decades from predominantly organophosphorus and N-methyl carbamate pesticides to a mix dominated by neonicotinoids and pyrethroids. The neonicotinoids are generally applied to US agricultural land at lower application rates per acre; however, they are considerably more toxic to insects and generally persist longer in the environment. We found a 48- and 4-fold increase in AITL from 1992 to 2014 for oral and contact toxicity, respectively. Neonicotinoids are primarily responsible for this increase, representing between 61 to nearly 99 percent of the total toxicity loading in 2014. The crops most responsible for the increase in AITL are corn and soybeans, with particularly large increases in relative soybean contributions to AITL between 2010 and 2014. Oral exposures are of potentially greater concern because of the relatively higher toxicity (low LD50s) and greater likelihood of exposure from residues in pollen, nectar, guttation water, and other environmental media. Using AITL to assess oral toxicity by class of pesticide, the neonicotinoids accounted for nearly 92 percent of total AITL from 1992 to 2014. Chlorpyrifos, the fifth most widely used insecticide during this time contributed just 1.4 percent of total AITL based on oral LD50s. Although we use some simplifying assumptions, our screening analysis demonstrates an increase in pesticide toxicity loading over the past 26 years, which potentially t On the other hand, lipophilic chemicals would tend to accumulate more in the lipid components of pollen and bee bread [ 13 ]. Table 1 Top ten most acutely toxic insecticides to honey bees by the oral route. The honey bee ( Apis mellifera ) is generally considered to be relatively sensitive to pesticides when compared to other bee species [ 23 ] and has historically been used as an indicator for ecotoxicological testing. However, there has also been some concern that the honey bee is not a good indicator for other bees or other beneficial insects because of species differences in autecology and sensitivity [ 24 ]. Information is being developed on the toxicity of insecticides to pollinators other than honey bees, notably bumble bees ( In order to register (license) a pesticide product in the US, applicants for registration must satisfy several criteria specified in the Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA) including but not limited to the product’s toxicity in a variety of biological systems, its fate and impact on the environment, and for certain pesticide products, proof of its performance (efficacy) [ 26 ]. Acute lethality (LD 50 ) testing in honey bees is required under FIFRA, however, field tests are only required on a rarely invoked case-by-case basis. In contrast, neonicotinoid residues from seed treatments may be found in the soil for months or even years after planting [ 12 , 28 ]. For example, neonicotinoid insecticides applied on coated seeds [ 18 ], mature citrus trees [ 29 ], or as soil drenches [ 12 ] on annual crops have been found to be effective at killing insects more than 50 days from treatment or planting of treated seeds. For perennial crops such as trees and vines, insecticidal efficacy can last for months up to a few years under certain conditions [ 30 ]. This is a simplifying assumption, which may or may not overestimate actual insecticide doses received by honey bees and other beneficial insects from seed treatments, depending on the specific circumstances. Based on a “residue per unit dose” estimation, it appears that seeding results in higher contamination of insects than an equivalent spray application but, due to the lower per hectare (or acre) rates of application for seed treatments, a comparable level of contamination in non-target arthropods can be expected [ 41 ]. We found that three neonicotinoid insecticide active ingredients (imidacloprid, thiamethoxam, and clothianidin) combine to contribute 91.8 percent of the total AITL O of all insecticides in the US. As noted earlier, chlorpyrifos, which is the fifth most widely used insecticide active ingredient, contributed only 1.4 percent of the total AITL O in the US from 1992–2014. Limitations of the AITL method Pesticide use by pounds (kilograms) applied or acres treated does not provide a comprehensive estimate of toxicity loading to an ecosystem. Therefore, the LD 50 dataset on honey bees is the only insect toxicity data available for a large number of pesticides registered for use in the US, which allowed us to compare historical trends for all relevant insecticide classes. Lethality is at the extreme end of the toxicity spectrum and using mortality as the endpoint for the AITL analysis or for risk assessment is a blunt instrument for evaluating the impact of pesticides on the ecosystem. Although current-use pesticides are applied at lower application rates per acre, they are more toxic to insects and persist in the environment for up to several weeks or longer, thus creating a persistent toxicity load in plants, soils, and surface waters that is substantially higher than that experienced by insects 20 or more years ago. The neonicotinoid insecticides, in particular imidacloprid, clothianidin, and thiamethoxam, are primarily responsible for this increased toxicity loading, accounting for 61percent (via contact toxicity) to 99 percent (via oral toxicity) of the total toxicity loading of all insecticides in 2014.

AbstractWith the exponential number of published data on neonicotinoids and fipronil during the last decade, an updated review of literature has been conducted in three parts. The present part focuses on gaps of knowledge that have been addressed after publication of the Worldwide Integrated Assessment (WIA) on systemic insecticides in 2015. More specifically, new data on the mode of action and metabolism of neonicotinoids and fipronil, and their toxicity to invertebrates and vertebrates, were obtained. We included the newly detected synergistic effects and/or interactions of these systemic insecticides with other insecticides, fungicides, herbicides, adjuvants, honeybee viruses, and parasites of honeybees. New studies have also investigated the contamination of all environmental compartments (air and dust, soil, water, sediments, and plants) as well as bees and apicultural products, food and beverages, and the exposure of invertebrates and vertebrates to such contaminants. Finally, we review new publications on remediation of neonicotinoids and fipronil, especially in water systems. Conclusions of the previous WIA in 2015 are reinforced; neonicotinoids and fipronil represent a major threat worldwide for biodiversity, ecosystems, and all the services the latter provide.

Neonicotinoids are a popular and widely-used class of insecticides whose heavy usage rates and purported negative impacts on bees and other beneficial insects has led to questions about their mobility and accumulation in the environment. Neonicotinoid compounds are currently registered for over 140 different crop uses in the United States, with commercial growers continuing to rely heavily on neonicotinoid insecticides for the control of key insect pests through a combination of in-ground and foliar applications. In 2008, the Wisconsin Department of Agriculture, Trade and Consumer Protection ( ✉ * E-mail: groves@entomology.wisc.edu 3 10 2018 13 10 e0201753 e0201753 19 10 2018 © 2018 Bradford et al This is an open access article distributed under the terms of the Creative Commons Attribution License , which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Abstract Neonicotinoids are a popular and widely-used class of insecticides whose heavy usage rates and purported negative impacts on bees and other beneficial insects has led to questions about their mobility and accumulation in the environment. Over 6.7 million pounds of neonicotinoid insecticides are now applied annually on 140 different crops in the United States, with the three most popular compounds, imidacloprid (IMD), clothianidin (CLO), and thiamethoxam (TMX) making up over 90% of agricultural usage nationally [ 7 , 8 ]. Most neonicotinoids are registered for application as seed treatments, foliar sprays, and in-furrow soil drenches, with seed treatments and soil applications constituting 60% of agricultural neonicotinoid usage [ 7 ]. The risk that these long field persistence times will translate into off-site movement of neonicotinoid compounds is further increased by the high water solubility of the major neonicotinoid compounds: IMD = 610 mg/L; CLO = 340 mg/L; and TMX = 4100 mg/L [ 4 ]. Indeed, laboratory and field studies have demonstrated a high risk of leaching associated with soil and seed applications of neonicotinoid insecticides [ 2 , 10 – 12 ]. Emerging concern about neonicotinoid contamination has motivated the development of ecosystem- and regional-scale water quality surveys [ 5 , 13 – 17 ]. Recent surveys in the US Midwest have also indicated that neonicotinoid contaminants can be found year-round in 10 different tributaries of the Great Lakes spanning six states [ 15 ]. Neonicotinoid detections in surface water systems at these concentrations are cause for alarm as aquatic invertebrates are key members of many freshwater ecosystems and some species are extremely sensitive to neonicotinoid insecticides, with acute toxicity endpoints reported down to 1 μg/L and chronic toxicity endpoints reported down to 0.1 μg/L [ 6 ]. In that paper Morrissey et al . suggest an ecological threshold for neonicotinoids be established at 0.2 μg/L long-term acute and 0.035 μg/L long-term chronic exposure limits. Similar aquatic invertebrate benchmarks of 0.385 μg/L acute exposure and 0.01 μg/L chronic exposure have been established by the US Environmental Protection Agency (EPA) as part of their registration review of IMD [ 29 ]. In 2008, DATCP added tests for select neonicotinoids (initially only TMX, later IMD, CLO, and others) as a part of this groundwater monitoring effort in response to significant public concern among rural communities about the rapidly expanding use of this new class of insecticides and their potential for accumulation in groundwater resources [ 30 , 31 ]. These surveys revealed concentrations of one or more neonicotinoid compounds in dozens of test wells, with most detections occurring in the Central Sands and Lower Wisconsin River Valley (LWRV) agroecosystems. Positive detections are illustrated by grey circles, with a larger diameter reflecting higher average total neonicotinoid detection at that particular location (range 0.01–3.93 μg/L). Wells tested but returning no positive detections over the surveillance interval are indicated as dots. Counties with at least one positive detection are shaded in grey. Chart ( B ) shows all positive detections for thiamethoxam, imidacloprid, and clothianidin over time, as well as the analytical limit of detection, which was initially 0.20 μg/L and later 0.05 μg/L. We hope that identifying specific explanatory factors contributing to higher levels of groundwater contamination can help build a more complete picture of the processes and risk factors associated with the use of neonicotinoid insecticides in an agricultural context. We detected TMX in high-capacity irrigation wells at concentrations (<0.05–1.67 μg/L; Table 3 ) similar to, if slightly lower, than those reported in the same region by the Wisconsin DATCP over the same time period (<0.05–3.89 μg/L; Table 2 ). While most previous neonicotinoid surveys have focused on surface water contamination or direct field-edge runoff, we reported All of the watersheds where well samples were collected for this study have high fractions of agricultural land use (28–50%; USDA NASS Cropland Data Layer, https://nassgeodata.gmu.edu/ ), reducing groundwater recharge routes that do not pass through a cultivated field surface, leaching agricultural contaminants into groundwater and subsequently into adjacent surface waters. Aquatic invertebrates living in these streams are highly sensitive to neonicotinoid insecticides and form a critical link in aquatic food chains [ 6 , 45 ]. We found significant variations in TMX detections between farms (generally separated by 5–20 km), and that even adjacent wells separated by less than 1 km could vary in detected TMX concentrations by over one order of magnitude ( Figs 2 and 3 ), suggesting neonicotinoid applications at individual fields may be responsible for elevated detections at nearby wells, rather than a more uniform detection profile indicative of a higher degree of groundwater mixing and dilution.

www.epa.gov. Retrieved 23 June 2023. "Conclusion on the peer review of the pesticide risk assessment for bees for the active substance clothianidin". EFSA Neonicotinoids (sometimes shortened to neonics ) are a class of neuro-active insecticides chemically similar to nicotine, developed by scientists at Shell and Bayer in the 1980s. Nicotine itself was used for centuries as an insecticide, until it was banned in the early 21st century. Neonicotinoids are among the widest-used insecticides in crop protection. They are also widely employed for veterina The US EPA operates a 15-year registration review cycle for all pesticides. The EPA granted a conditional registration to clothianidin in 2003. The EPA issues conditional registrations when a pesticide meets the standard for registration, but there are outstanding data requirements. Thiamethoxam is approved for use as an antimicrobial pesticide wood preservative and as a pesticide; it was first approved in 1999. Imidacloprid was registered in 1994. As all neonicotinoids were registered after 1984 they were not subject to reregistration, but because of environmental concerns, especially concerning bees, the EPA opened dockets to evaluate them. The registration review docket for imidacloprid opened in December 2008, and the docket for nithiazine opened in March 2009. To best take advantage of new research as it becomes available, the EPA moved ahead the docket openings for the remaining neonicotinoids on the registration review schedule (acetamiprid, clothianidin, dinotefuran, thiacloprid, and thiamethoxam) to FY 2012. The EPA said that it expected to complete the review for the neonicotinoids in 2018. In March 2012, the Center for Food Safety, Pesticide Action Network, Beyond Pesticides and a group of beekeepers filed an Emergency Petition with the EPA asking the agency to suspend the use of clothianidin. The agency denied the petition. In March 2013, the US EPA was sued by the same group, with the Sierra… In 2018 the EU banned the three main neonicotinoids (clothianidin, imidacloprid and thiamethoxam) for all outdoor uses. Several US states have restricted neonicotinoids out of concern for pollinators and bees. == History == The precursor to nithiazine was first synthesized by Henry Feuer, a chemist at Purdue University, in 1970. Shell researchers found in screening that this precursor showed insecticide potential and refined it to develop nithiazine. In 1984 nithiazine's mode of action was found to be as a postsynaptic acetylcholine receptor agonist, the same as nicotine. The EPA issues conditional registrations when a pesticide meets the standard for registration, but there are outstanding data requirements. Thiamethoxam is approved for use as an antimicrobial pesticide wood preservative and as a pesticide; it was first approved in 1999. Imidacloprid was registered in 1994. As all neonicotinoids were registered after 1984 they were not subject to reregistration, but because of environmental concerns, especially concerning bees, the EPA opened dockets to evaluate them. The registration review docket for imidacloprid opened in December 2008, and the docket for nithiazine opened in March 2009. In March 2013, the US EPA was sued by the same group, with the Sierra Club and the Center for Environmental Health joining, which accused the agency of performing inadequate toxicity evaluations and allowing insecticide In 2014, under the Obama administration, a blanket ban was issued against the use of neonicotinoids on National Wildlife Refuges in response to concerns about off-target effects of the pesticide, and a lawsuit from environmental groups. In 2018, the Trump administration reversed this decision, stating that decisions on neonicotinoid usage on farms in wildlife refuges will be made on a case-by-case basis. In May 2019, the Environmental Protection Agency revoked approval for a dozen pesticides containing clothianidin and thiamethoxam as part of a legal settlement. === European Union === The first neonic was approved in the EU in 2005. In 2008, Germany revoked the registration of clothianidin for use on seed corn after an incident that resulted in the death of millions of nearby honey bees. An investigation revealed that it was caused by a combination of factors: failure to use a polymer seed coating known as a "sticker"; weather conditions that resulted in late planting when nearby rapeseed crops were in bloom; a particular type of air-driven equipment used to sow the seeds which apparently blew clothianidin-laden dust off the seeds and into the air as the seeds were ejected from the machine into the ground; dry and windy conditions at the time of planting that blew the dust into the nearby canola fields where honey bees were foraging. In Germany, clothianidin use was also restricted in 2008 for a short period on rapeseed. The law restricted the use of imidacloprid, clothianidin, and thiamethoxam for seed treatment, soil application (granules), and foliar treatment in crops attractive to bees. Temporary suspensions had previously been enacted in France, Germany, and Italy. In Switzerland, where neonicotinoids were never used in alpine areas, neonics were banned because of accidental poisonings of bee populations and the relatively low safety margin for other beneficial insects. In March 2017, The Guardian printed an article that claimed that they had obtained information that indicated that the European Commission wanted a complete ban and cited "high acute risks to bees". A vote on the ban was expected in 2017 but delayed until early 2018 to assess the scientific findings. On 27 April 2018, member states of the European Union agreed upon a total ban on neonicotinoid insecticide use, except within closed greenhouses, to be imposed from the end of 2018. The ban applies to the three main neonicotinoid active compounds: clothianidin, imidacloprid and thiamethoxam. Use of the three compounds had been partially restricted in 2013.

Reduction in pollinator abundance (predominantly honeybees) stemming from environmental and chemical stressors notably neonicotinoid pesticides poses serious threats to biodiversity and agricultural productivity. This study presents a scalable machine learning framework to foresee honey yield and assess the impact of neonicotinoid exposure. Drawing upon a curated dataset, of 825 records encompassing 16 agro-environmental and chemical parameters including colony counts, yield metrics, and pesticide residue concentrations. Subsequently, we assessed 13 classification models, marked improvement was evident, as ensemble models consistently outperformed individual learners. Notably, our proposed voting classifier (AgriBuzzEnsemble), which synergistically fuses Support Vector Machine (SVM) and Gaussian Naive Bayes (GNB), surpassed all baseline models, showcasing robust accuracy of 98%, a Matthews Correlation Coefficient (MCC) of 0.9751, a specificity of 0.9917, and an ROC AUC of 0.9985. Data preparation encompassed missing value imputation, outlier detection, feature scaling, and SMOTE based class balancing. For subsequent analysis, we employed Z-score filtering to detect and remove outliers, followed by a log1p transformation to mitigate skewness adhering to standard and well established preprocessing standards. Correlation analysis and statistical tests comprising McNemar's Test, ANOVA, and Tukey's HSD validated model reliability and confirmed the negative association between neonicotinoid burden and honey yield. Our proposed framework AgriBuzzEnsemble facilitates precision focused beekeeping by identifying yield risk zones and can be generalized to other regions facing pollinator stress, offering a robust and interpretable solution for sustainable agricultural planning.