油菜花农药害死小蜜蜂

Chronic exposure to neonicotinoid insecticides has been linked to reduced survival of pollinating insects at both the individual and colony level, but so far only experimentally. Analyses of large-scale datasets to investigate the real-world links between the use of neonicotinoids and pollinator mortality are lacking. Moreover, the impacts of neonicotinoid seed coatings in reducing subsequent applications of foliar insecticide sprays and increasing crop yield are not known, despite the supposed benefits of this practice driving widespread use. Here, we combine large-scale pesticide usage and yield observations from oilseed rape with those detailing honey bee colony losses over an 11 year period and reveal a correlation between honey bee colony losses and national-scale imidacloprid (a neonicotinoid) usage patterns across England and Wales. We also provide the first evidence that farmers who use neonicotinoid seed coatings reduce the number of subsequent applications of foliar insecticide sprays and may derive an economic return. Our results inform the societal discussion on the pollinator costs and farming benefits of prophylactic neonicotinoid usage on a mass flowering crop.

Among bee species, the western honey bee (Apis mellifera) is preferred in monitoring studies performed in the agricultural landscape, while bee matrices, pollen, and honey are mostly a subject of these studies due to their unique composition. A justified question about the relevance of other bee matrices, like larvae, foragers, beebread, and/or wax, has been raised. The ability of different bee matrices (wax, pollen grains, bee bread, foragers, larvae, nectar, and honey) to absorb pesticide residues is subjected in this study. All samples were collected during a crop flowering season (oilseed rape) on intensively managed agricultural land in Slovakia and Germany. The observed high variability in residue levels, profile, and number of detections among studied matrices from Germany, west, and east Slovakia gave us an assumption of the use of different agricultural practices between these two countries. Fungicides clearly dominated across all samples in all sampling regions. The increased pesticide profile positively correlated with the oilseed rape pollen grains in pollen pellets and/or bee bread. Bee wax, pollen, and bee bread showed a high number of detected active substances and total residue concentrations among matrices, indicating their high ability to absorb pesticide residues in the surrounding hive environment.

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Nature-based agriculture that reduces dependency on chemical inputs requires using ecological principles for sustainable agro-ecosystems, aiming to balance ecology, economics and social justice. There is growing evidence that pollinator-dependent crops with high insect, particularly bee, pollination service can give higher yields. However, the interacting effects between insect pollination and agricultural inputs on crop yields and farm economics remain to be established to reconcile food production with biodiversity conservation. We quantified individual and combined effects of pesticides, insect pollination and soil quality on oilseed rape (Brassica napus L.) yield and gross margin, using a total of 294 farmers' fields surveyed between 2013 and 2016. We show that yield and gross margins are greater (15–40%) in fields with higher pollinator abundance than in fields with reduced pollinator abundance. This effect is, however, strongly reduced by pesticide use. Greater yields may be achieved by either increasing agrochemicals or increasing bee abundance, but crop economic returns were only increased by the latter, because pesticides did not increase yields while their costs reduced gross margins.

Agricultural pesticides are key contributors to pollinator decline worldwide. However, methods for quantifying impacts associated with pollinator exposure to pesticides are currently missing in comparative risk screening, chemical substitution and prioritization, and life cycle impact assessment methods. To address this gap, we developed a method for quantifying pesticide field exposure and ecotoxicity effects of honey bees as most economically important pollinator species worldwide. We defined bee intake and dermal contact fractions representing respectively oral and dermal exposure per unit mass applied, and tested our model on two pesticides applied to oilseed rape. Our results show that exposure varies between types of forager bees, with highest dermal contact fraction of 59 ppm in nectar foragers for lambda-cyhalothrin (insecticide), and highest oral intake fractions of 32 and 190 ppm in nectar foragers for boscalid (fungicide) and lambda-cyhalothrin, respectively. Hive oral exposure is up to 115 times higher than forager oral exposure. Combining exposure with effect estimates yields impacts, which are three orders of magnitude higher for the insecticide. Overall, nectar foragers are the most affected forager type for both pesticides, dominated by oral exposure. Our framework constitutes an important step toward integrating pollinator impacts in chemical substitution and life cycle impact assessment, and should be expanded to cover all relevant pesticide-crop combinations.

In agricultural landscapes, solitary bees occur in a large diversity of species and are important for crop and wildflower pollination. They are distinguished from honey bees and bumble bees by their solitary lifestyle as well as different nesting strategies, phenologies, and floral preferences. Their ecological traits and presence in agricultural landscapes imply potential exposure to pesticides and suggest a need to conduct ecological risk assessments for solitary bees. However, assessing risks to the large diversity of managed and wild bees across landscapes and regions poses a formidable challenge. Population models provide tools to estimate potential population‐level effects of pesticide exposures, can support field study design and interpretation, and can be applied to expand study data to untested conditions. We present a population model for solitary bees, SolBeePopecotox, developed for use in the context of ecological risk assessments. The trait‐based model extends a previous version with the explicit representation of exposures to pesticides from relevant routes. Effects are implemented in the model using a simplified toxicokinetic–toxicodynamic model, BeeGUTS (GUTS = generalized unified threshold model for survival), adapted specifically for bees. We evaluated the model with data from semifield studies conducted with the red mason bee, Osmia bicornis, in which bees were foraging in tunnels over control and insecticide‐treated oilseed rape fields. We extended the simulations to capture hypothetical semifield studies with two soil‐nesting species, Nomia melanderi and Eucera pruinosa, which are difficult to test in empirical studies. The model provides a versatile tool for higher‐tier risk assessments, for instance, to estimate effects of potential exposures, expanding available study data to untested species, environmental conditions, or exposure scenarios. Environ Toxicol Chem 2024;43:2645–2661. © 2024 SETAC

In an agricultural environment, where crops are treated with pesticides, bees are likely to be exposed to a range of chemical compounds in a variety of ways. The extent to which different bee species are affected by these chemicals, depends to a large extent on the concentrations and type of exposure. We quantified the presence of selected pesticide compounds in the pollen of two different entomophilous crops; oilseed rape (Brassica napus) and broad bean (Vicia faba). Sampling was performed in 12 sites in Ireland and our results were compared with the pollen loads of honey bees and bumble bees actively foraging on those crops in those same sites. Detections were compound specific, and the timing of pesticide application in relation to sampling likely influenced the final residue contamination levels. Most detections originated from compounds that were not recently applied on the fields, and samples from B. napus fields were more contaminated compared to those from V. faba fields. Crop pollen was contaminated only with fungicides, honey bee pollen loads contained mainly fungicides, while more insecticides were detected in bumble bee pollen loads. The highest number of compounds and most detections were observed in bumble bee pollen loads, where notably, all five neonicotinoids assessed (acetamiprid, clothianidin, imidacloprid, thiacloprid, and thiamethoxam) were detected despite the no recent application of these compounds on the fields where samples were collected. The concentrations of neonicotinoid insecticides were positively correlated with the number of wild plant species present in the bumble bee-collected pollen samples, but this relationship could not be verified for honey bees. The compounds azoxystrobin, boscalid and thiamethoxam formed the most common pesticide combination in pollen. Our results raise concerns about potential long-term bee exposure to multiple residues and question whether honey bees are suitable surrogates for pesticide risk assessments for all bee species.

Neonicotinoid residues in nectar and pollen from crop plants have been implicated as one of the potential factors causing the declines of honey bee populations. Median residues of thiamethoxam in pollen collected from honey bees after foraging on flowering seed treated maize were found to be between 1 and 7 µg/kg, median residues of the metabolite CGA322704 (clothianidin) in the pollen were between 1 and 4 µg/kg. In oilseed rape, median residues of thiamethoxam found in pollen collected from bees were between <1 and 3.5 µg/kg and in nectar from foraging bees were between 0.65 and 2.4 µg/kg. Median residues of CGA322704 in pollen and nectar in the oilseed rape trials were all below the limit of quantification (1 µg/kg). Residues in the hive were even lower in both the maize and oilseed rape trials, being at or below the level of detection of 1 µg/kg for bee bread in the hive and at or below the level of detection of 0.5 µg/kg for hive nectar, honey and royal jelly samples. The long-term risk to honey bee colonies in the field was also investigated, including the sensitive overwintering stage, from four years consecutive single treatment crop exposures to flowering maize and oilseed rape grown from thiamethoxam treated seeds at rates recommended for insect control. Throughout the study, mortality, foraging behavior, colony strength, colony weight, brood development and food storage levels were similar between treatment and control colonies. Detailed examination of brood development throughout the year demonstrated that colonies exposed to the treated crop were able to successfully overwinter and had a similar health status to the control colonies in the following spring. We conclude that these data demonstrate there is a low risk to honey bees from systemic residues in nectar and pollen following the use of thiamethoxam as a seed treatment on oilseed rape and maize.

Forage availability has been suggested as one driver of the observed decline in honeybees. However, little is known about the effects of its spatiotemporal variation on colony success. We present a modelling framework for assessing honeybee colony viability in cropping systems. Based on two real farmland structures, we developed a landscape generator to design cropping systems varying in crop species identity, diversity, and relative abundance. The landscape scenarios generated were evaluated using the existing honeybee colony model BEEHAVE, which links foraging to in-hive dynamics. We thereby explored how different cropping systems determine spatiotemporal forage availability and, in turn, honeybee colony viability (e.g., time to extinction, TTE) and resilience (indicated by, e.g. brood mortality). To assess overall colony viability, we developed metrics, PH and PP, which quantified how much nectar and pollen provided by a cropping system per year was converted into a colony’s adult worker population. Both crop species identity and diversity determined the temporal continuity in nectar and pollen supply and thus colony viability. Overall farmland structure and relative crop abundance were less important, but details mattered. For monocultures and for four-crop species systems composed of cereals, oilseed rape, maize and sunflower, PH and PP were below the viability threshold. Such cropping systems showed frequent, badly timed, and prolonged forage gaps leading to detrimental cascading effects on life stages and in-hive work force, which critically reduced colony resilience. Four-crop systems composed of rye-grass-dandelion pasture, trefoil-grass pasture, sunflower and phacelia ensured continuous nectar and pollen supply resulting in TTE > 5 years, and PH (269.5 kg) and PP (108 kg) being above viability thresholds for five years. Overall, trefoil-grass pasture, oilseed rape, buckwheat and phacelia improved the temporal continuity in forage supply and colony’s viability. Our results are hypothetical as they are obtained from simplified landscape settings, but they nevertheless match empirical observations, in particular the viability threshold. Our framework can be used to assess the effects of cropping systems on honeybee viability and to develop land-use strategies that help maintain pollination services by avoiding prolonged and badly timed forage gaps.

Risk assessment of plant protection products (PPPs) will be conducted before authorization for their possible effects on non-target organisms, including honey bees. Tank mixtures are often common practice by farmers, and mostly their effects on honey bees are not routinely assessed. To enable a realistic assessment of laboratory-reported effects of a combination of the insecticide thiacloprid and fungicide prochloraz on honey bees, a large-scale field study with spray application in winter oilseed rape was conducted in four regions in Germany. Several parameters were investigated, including mortality, flight activity, and colony development. Residue analysis of various materials (e.g., dead bees, nectar, and pollen) was conducted to assess exposure level. We observed several intoxication symptoms 2 h after application, including a high number of moribund bees and dead bees on the first day after application (DAA +1) compared to the control. Adverse effects were observed on the number of open brood cells, with a significant reduction of approximately 22% compared to control over the experimental period. High residue concentrations were detected on flowers and dead bees on the day of application, which decreased rapidly within six days. The residue concentrations detected were higher in bee-collected materials than in materials stored in the hive. In conclusion, exposure to a combination containing thiacloprid-prochloraz poses a high risk to honey bees. Thus, the application of such a mixture on flowering crops is restricted in Germany.

Over the past years, increasing attention has been drawn to the adverse effects of agricultural pesticide use on pollinators, with honeybees being especially vulnerable. The aim of this study was to evaluate the levels of residues detectable and/or quantifiable of neonicotinoid pesticides and other pesticides in biological materials (bees, bee brood, etc.) and beehive products (honey, pollen, etc.) applied as seed dressings in rapeseed and sunflower plants in two growing seasons (2020–2021) in fields located in three agro-climatic regions in Romania. The study involved the comparative sampling of hive products (honey, pollen, adult bees, and brood) from experimental and control apiaries, followed by pesticide residue analysis in an accredited laboratory (Primoris) using validated chromatographic techniques (LC-MS/MS and GC-MS). Toxicological analyses of 96 samples, including bees, bee brood, honey, and pollen, confirmed the presence of residues in 46 samples, including 10 bee samples, 10 bee brood samples, 18 honey samples, and 8 pollen bread samples. The mean pesticide residue concentrations detected in hive products were 0.032 mg/kg in honey, 0.061 mg/kg in pollen, 0.167 mg/kg in bees, and 0.371 mg/kg in bee brood. The results highlight the exposure of honeybee colonies to multiple sources of pesticide residue contamination, under conditions where legal recommendations for the controlled application of agricultural treatments are not followed. The study provides relevant evidence for strengthening the risk assessment framework and underscores the need for adopting stricter monitoring and regulatory measures to ensure the protection of honeybee colony health.

Honeybees are major pollinators of agricultural crops and many other plants in natural ecosystems alike. In recent years, managed honeybee colonies have decreased rapidly. The application of pesticides is hypothesized to be an important route leading to colony loss. Herein, a quick, easy, cheap, effective, rugged, and safe (QuEChERS) method was used to determine eight highly detectable pesticides (carbendazim, prochloraz, pyrimethanil, fenpropathrin, chlorpyrifos, imidacloprid, thiamethoxam, and acetamiprid) in rape flowers. A field experiment was conducted at the recommended dose to evaluate the contact exposure risk posed to honeybees for 0–14 days after treatment. The initial residue deposits of neonicotinoids and fungicides among these compounds were 0.4–1.3 mg/kg and 11.7–32.3 mg/kg, respectively, and 6.4 mg/kg for fenpropathrin and 4.2 mg/kg for chlorpyrifos. The risk was quantified using the flower hazard quotient (FHQ) value. According to the data, we considered imidacloprid, thiamethoxam, chlorpyrifos, fenpropathrin, and prochloraz to pose an unacceptable risk to honeybees after spraying in fields, while fungicides (carbendazim and pyrimethanil) and acetamiprid posed moderate or acceptable risks to honeybees. Therefore, acetamiprid can be used instead of imidacloprid and thiamethoxam to protect rape from some insects in agriculture, and the application of prochloraz should be reduced.

Environmental pollution worldwide is systemic in nature and is associated with the use of pesticides from various groups as plant protection products. Agricultural pesticides accidentally affect beneficial, non-target insects, particularly the honeybee (Apis mellifera L.), which leads to mass poisoning and contamination of beekeeping products with toxic compounds. The aim of the research was to determine the accumulation of pesticides from different groups in soil, plants, dead bees, and beekeeping products in apiaries in various regions of Ukraine during the mass deaths of bee colonies in 2021–2022. Pesticide content in biological samples was determined using liquid mass spectrometry (UPLC-MS/MS) and gas mass spectrometry (GC-MS/MS). The main pesticides that contaminate the soil, plants, and beekeeping products, causing the death of bee colonies, are insecticides and fungicides in various combinations. In isolated cases, bee colony deaths were registered from a single insecticide. More often, two or more pesticides were found in the soil, plants, dead bees, and beekeeping products. The total list of detected pesticides in soils, grain, plant biomass, bees, brood, bee bread, and honey included 23 compounds. The maximum number of pesticides forming a cocktail in biological samples included 5 substances. Most frequently, pesticide combinations that contaminated the soil and plants and caused bee deaths included insecticides from the pyrethroid group: lambda-cyhalothrin and cypermethrin, and from the neonicotinoid group: clothianidin and imidacloprid, as well as fungicides from the triazole group: tebuconazole, cyproconazole, and strobilurins: azoxystrobin in various concentrations. The cause of bee poisoning was the contamination of the inflorescences of non-target crops, such as maple and meadow grasses, as well as wind-pollinated and self-pollinated crops, including wheat, peas, soybeans, and potatoes, located within the flight radius of bees. Among entomophilous plants, rapeseed and sunflower were the main crops, the pesticide treatment of which contributed to soil contamination, plant biomass, and bee poisoning during honey collection. It was found that the concentration of certain pesticides in dead bees reached, and in some cases exceeded, the acute oral toxic dose LD50 by tens of times. The results of the research could form the basis for determining the cumulative toxicity of combinations of different pesticides for beneficial insects and for developing biological plant protection products.

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The nitro-substituted neonicotinoid insecticides, which include imidacloprid, thiamethoxam and clothianidin, are widely used to control a range of important agricultural pests both by foliar applications and also as seed dressings and by soil application. Since they exhibit systemic properties, exposure of bees may occur as a result of residues present in the nectar and/or pollen of seed- or soil-treated crop plants and so they have been the subject of much debate about whether they cause adverse effects in pollinating insects under field conditions. Due to these perceived concerns, the use of the three neonicotinoids imidacloprid, clothianidin and thiamethoxam has been temporarily suspended in the European Union for seed treatment, soil application and foliar treatment in crops attractive to bees. Monitoring data from a number of countries are available to assess the presence of neonicotinoid residues in honey bee samples and possible impacts at the colony level and these are reviewed here together with a number of field studies which have looked at the impact of clothiandin on honey bees in relation to specific crop use and in particular with oilseed rape. Currently there is considerable uncertainty with regards to the regulatory testing requirements for field studies. Accordingly, a testing protocol was developed to address any acute and chronic risks from oilseed rape seeds containing a coating with 10 g clothianidin and 2 g beta-cyfluthrin per kg seeds (Elado®) for managed honey bee (Apis mellifera) colonies, commercially bred bumble bee (Bombus terrestris) colonies and red mason bees (Osmia bicornis) as a representative solitary bee species. This is described here together with a summary of the results obtained as an introduction to the study details given in the following papers in this issue.

Recently, there has been a widespread decline in honeybee (Apis mellifera) colonies globally, disrupting ecological balance and reducing the pollination capacity of many entomophilous plants. One of the primary causes of bee family deaths is the increasing use of pesticides, particularly insecticides, in agricultural practice. This study aimed to identify the causes of bee family mortality in various regions of Ukraine during 2021–2022 and to determine the breakdown potential of different pesticide groups in honey. Pesticide residues in biological samples were analyzed using liquid chromatography-mass spectrometry (UPLC-MS/MS) and gas chromatography-mass spectrometry (GC-MS/MS). In the bodies of dead bees, residues of various pesticides from different chemical groups, as well as their mixtures, were detected. In most cases, the cause of bee poisoning was mixtures of pyrethroids and neonicotinoids: thiamethoxam, clothianidin, and lambda-cyhalothrin; imidacloprid, lambda-cyhalothrin, and thiamethoxam; as well as clothianidin and lambda-cyhalothrin. The primary pesticides found in honey were neonicotinoids (58.8%), triazoles (29.6%), strobilurins (6.5%), and benzimidazoles (5.1%). Most pesticide levels did not exceed the maximum allowable levels in honey. The neonicotinoids detected in honey included thiacloprid, acetamiprid, imidacloprid, clothianidin, and thiamethoxam. The triazoles detected included tebuconazole, cyproconazole, flutriafol, and epoxiconazole; strobilurins included picoxystrobin, pyraclostrobin, and azoxystrobin; and benzimidazoles included carbendazim and thiophanate-methyl. Residues of neonicotinoids, triazoles, benzimidazoles, and strobilurins in honey did not undergo degradation over 12 months of storage at 4 °C. Storing honey at 20 °C after 12 months increased the degradation of thiacloprid by 21.2%, acetamiprid by 20.7%, and flutriafol by 36.3%. Between the 9th and 12th months at 20 °C, picoxystrobin concentration decreased by 24.5–38.0%, and carbendazim concentration decreased by 80.0% to a complete breakdown of residues in honey. The degradation of thiophanate-methyl in honey at 20 °C reached 28.0% by the 6th month, 46.0% by the 9th month, and 55.4% by the 12th month. This persistence of most pesticides in honey poses a significant risk of toxic effects on bee families as well as on human health.

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Abstract Cultivation of the mass‐flowering crop oilseed rape (OSR), Brassica napus, can provide insects with super‐abundant nectar and pollen while in bloom. Several authors have suggested breeding cultivars to produce more abundant nectar and pollen to help mitigate insect decline. However, in Britain most, 95%, OSR blooms in spring (March–May), which has been suggested to be a period of nectar surplus and reduced exploitative competition. Therefore, a large proportion of floral resources produced by OSR during this period may be uncollected. Although there has been extensive work examining OSR nectar and pollen production, no study, to our knowledge, has measured this in relation to the demand by the flower‐visiting insects. Here we quantified the percentage of nectar produced by spring blooming OSR which was uncollected in four OSR fields per year over 2 years. This was achieved by measuring the nectar in both insect accessible and inaccessible (i.e. mesh‐covered) flowers. We also quantified uncollected pollen in flowers at the beginning and the end of anthesis using a haemocytometer. Most of the nectar (69%) and a fifth of pollen (19%) was uncollected in spring blooming OSR. Based on the estimates of nectar production and observed number of insects, nectar supply per insect was estimated at 2204 μL nectar insect−1 h−1, which exceeds potential collection rates by flower‐visiting insects. Given the majority of B. napus is spring blooming, breeding cultivars of OSR which produce more nectar, while not being detrimental to flower‐visiting insects, may be of little conservation benefit.

BACKGROUND Pollen beetles are key pests in oilseed rape (OSR) production. These beetles use visual and olfactory cues to locate their host plants at specific phenological stages, hence trap cropping may represent an alternative pest control strategy. In this study, a trap crop strategy for spring OSR has been developed. To elaborate such a trap cropping system, a pest control measure that eradicates the attracted beetles in the trap crop before they migrate further into the main crop has been included in the final trap cropping strategy. RESULTS Testing yellow-flowering turnip rape and one yellow- and two cream-coloured-flowering OSR cultivars as potential crops in different trap cropping strategies, we found that pollen beetles clearly preferred turnip rape over the cream-coloured and yellow OSR cultivars, and preferred the yellow OSR cultivar over the two cream-coloured cultivars. This behaviour was related to the plant growth stage and the associated volatile and colour signals of the tested cultivars. Using turnip rape as a trap crop and testing kairomone- or insecticide-assisted trap cropping as the pest control strategy was as effective as compared with whole fields treated with a standard pesticide. CONCLUSION Combining a turnip rape cultivar as trap crop with kairomone traps placed in the trap crop as killing agent can enable a renunciation of pesticides in spring OSR production. This article is protected by copyright. All rights reserved.

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This paper presents studies performed for the monitoring of imidacloprid, clothianidin and thiamethoxam residues applied as seed treatment in rapeseed (Brassica napus ssp. oleifera), maize (Zea mays) and sunflower crops (Helianthus annuus). The experiments were located in representative areas of the mentioned crops. Residue levels were determined in plant samples at different phenological development stages, including flowers, as well as in bees and hive products (pollen, honeycomb, honey) by liquid chromatography/tandem mass spectroscopy (LC-MS/MS). The analyses were performed in ISO 17025-accredited laboratories, referring to the limit of quantification (LOQ), characteristic of the method used to determine the residues. In 2019, the percentage of samples that contained residues of the three substances, applied to the seed, was 16.39%, representing 20 samples out of the total of 122 analyzed samples. In 2020, 10 samples contained neonicotinoid residues above the LOQ, including 5 soil samples and 5 plant samples, representing 6.17% of the total samples. In 2021, from 149 samples with neonicotinoid applied as seed treatment, residues were identified in 12 soil samples and 11 plant samples, representing 15.43% of the total number of samples. In 2022, only 12 soil samples and 1 pasture sample contained residues above the LOQ. The results show that the highest percentage of samples with residues above the LOQ was recorded by the soil samples, while the flower and bee samples had the lowest percentages of samples with residues above the LOQ; no residues of the three neonicotinoid substances were identified in the honey samples.

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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 threatens the health of honey bees and other pollinators and may contribute to declines in beneficial insect populations as well as insectivorous birds and other insect consumers.

In recent years there has been growing concern regarding the sudden and unexplained failure of honeybee (Apis mellifera) colonies. Several factors have been suggested, including pesticides. In an effort to regulate their impact, guidance published by the European Food Safety Authority (EFSA) has recommended that the magnitude of effects on exposed colonies should not exceed 7% reduction in colony size after 2 brood cycles. However, fears have been raised regarding the practicality of measuring such a loss in the field. It is also unclear how this protection goal relates to maintaining the ecosystem services provided by bees, which we argue should be a primary objective for regulators. Here, we evaluate what these protection goals mean in relation to ecosystems performance using a computational colony model that incorporates mechanisms to simulate both lethal and sublethal pesticide effects. To these simulations, we apply a testing regime similar to that commonly used in field trials to produce standard assessment metrics. By relating these measures to losses in forager activity, we aim to identify which could be used as effective indicators of reduced ecoservice and to quantify acceptable limits below which performance can be maintained. Our findings show that loss of colony size is the best indicator of reduced ecoservice. Metrics that focus on specific colony functions such as increased brood or forager mortality are ineffective indicators for all types of simulated pesticide effects. At the levels of colony loss recommended by EFSA, using our default parameterization, we predict a loss of ecosystems performance of 3% to 4%. However, based on an extensive sensitivity analysis, it is clear that this estimate is subject to substantial uncertainty with losses under alternative parameterizations of up to 14%. Nevertheless, our model provides a valuable framework for assessing protection goals, allowing regulators to test relevant impacts and quantify their magnitude. Integr Environ Assess Manag 2018;14:750–758. © 2018 Crown Copyright and SETAC

Abstract Honey bees, essential pollinators for a wide range of important crops, are currently at risk from exposure to neonicotinoid insecticides. In this study we assessed the impact of two most commonly used neonicotinoid insecticides namely imidacloprid and thiamethoxam on honey bee, Apis cerana through controlled feeding experiment at doses of 15 ng/bee, 30 ng/bee, 60 ng/bee and 120 ng/bee. Mortality was recorded at 4, 8, 18, 24 and 48 h after exposure to insecticides. At 24 h, imidacloprid and thiamethoxam @ 60 ng/bee caused 43.75 and 72.50 % mortality, respectively. After 18 h of exposure to 120 ng/bee of imidacloprid and thiamethoxam, mortality rates reached 82.5 % and 87.5 %, respectively. Significant, dose-dependent effects of imidacloprid and thiamethoxam on bee mortality were observed over time, with the highest concentrations (120 ng/bee and 60 ng/bee) producing the most pronounced effects. Furthermore, prolonged exposure to lower doses (15 ng/bee and 30 ng/bee) induced adverse effects such as trembling and impaired coordination in bees. Overall, the differences in toxicity between imidacloprid and thiamethoxam were largely non-significant across doses and exposure durations. Field studies on foraging activity suggested that imidacloprid can negatively impact honey bee foraging behavior. Three days after exposure to sucrose spiked with imidacloprid at 0.28 mg/kg, foraging activity dropped from 62.67 bees per 10 min before treatment to 6.76 bees per 10 min. These findings emphasize the importance of addressing the harmful effects of neonicotinoids on honey bees, which impact both their behavior and survival, particularly with prolonged exposure.

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