Effects of the neonicotinoids acetamiprid and thiacloprid in their commercial formulations on soil fauna

Multiple signal-enhanced electrochemiluminescence aptamer sensors based on carboxylated ruthenium (II) complexes for acetamiprid detection

BACKGROUND

Rapid and sensitive detection for acetamiprid, a kind of widely used neonicotinoid insecticide, is very meaningful for the development of modern agriculture and the protection of human health. Highly stable electrochemiluminescence (ECL) materials are one of the key factors in ECL sensing technology. ECL materials prepared by porous materials (e.g., MOFs) coated with chromophores have been used for ECL sensing detection, but these materials have poor stability because the chromophores escape when they are in aqueous solution. Therefore, the development of highly stable ECL materials is of great significance to improve the sensitivity of ECL sensing technology.

RESULTS

In this work, by combining etched metal-organic frameworks (E-UIO-66-NH2) as carrier with Tris(4,4'-dicarboxylic acid-2,2'-bipyridine)Ru(II) chloride (Ru(dcbpy)32+) as signal probe via amide bonds, highly stable nanocomposites (E-UIO-66-NH2-Ru) with excellent ECL performance were firstly prepared. Then, using MoS2 loaded with AuNPs as substrate material and co-reactant promoter, a signal off-on-off ECL aptamer sensor was prepared for sensitive detection of acetamiprid. Due to the excellent catalytic activity of E-UIO-66-NH2-Ru and MoS2@Au towards K2S2O8, the ECL signals can be enhanced by multiple signal enhancement pathways, the prepared ECL aptamer sensor could achieve sensitive detection of acetamiprid in the linear range of 10-13 to10-7 mol L-1, with the limit of detection (LOD) of 2.78ⅹ10-15 mol L-1 (S/N = 3). After the evaluation of actual sample testing, this sensing platform was proven to be an effective method for the detection of acetamiprid in food and agricultural products.

SIGNIFICANCE AND NOVELTY

The E-UIO-66-NH2-Ru prepared by linking Ru(dcbpy)32+ to E-UIO-66-NH2 via amide bonding has very high stability. The synergistic catalytic effect of MoS2 and AuNPs enhanced the ECL signal. By exploring the sensing mechanism and evaluating the actual sample tests, the proposed signal "on-off" ECL sensing strategy was proved to be an effective and excellent ECL sensing method for sensitive and stable detection of acetamiprid.

Risk analysis for groundwater intakes based on the example of neonicotinoids

Neonicotinoids are a class of broad-spectrum insecticides that are dominant in the world market. They are widely distributed in the environment. Understanding the sources, distribution, and fate of these contaminants is critical to mitigating their effects and maintaining the health of aquatic ecosystems. Contamination of surface and groundwater by neonicotinoids has become a widespread problem worldwide, requiring comprehensive action to accurately determine the mechanisms behind the migration of these pesticides, their properties, and their adverse effects on the environment. A new approach to risk analysis for groundwater intake contamination with emerging contaminants was proposed. It was conducted on the example of four neonicotinoids (acetamiprid, clothianidin, thiamethoxam, and imidacloprid) in relation to groundwater accessed by a hypothetical groundwater intake, based on data obtained in laboratory tests using a dynamic method (column experiments). The results of the risk analysis conducted have shown that in this case study the use of acetamiprid and thiamethoxam for agricultural purposes poses an acceptable risk, and does not pose a risk to the quality of groundwater extracted from the intake for food purposes. Consequently, it does not pose a risk to the health and life of humans and other organisms depending on that water. The opposite situation is observed for clothianidin and imidacloprid, which pose a higher risk of groundwater contamination. For higher maximum concentration of neonicotinoids used in the risk analysis, the concentration of clothianidin and imidacloprid in the groundwater intake significantly (from several to several hundred thousand times) exceeds the maximum permissible levels for drinking water (<0.1 μg/L). This risk exists even if the insecticides containing these pesticides are used according to the information sheet provided by the manufacturer (lower maximum concentration), which results in exceeding the maximum permissible levels for drinking water from several to several hundred times.

Toxicity evaluation of neonicotinoids to earthworm (Eisenia fetida) behaviors by a novel locomotion tracking assay

Pesticides are substances used for controlling, preventing, and repelling pests in agriculture. Among them, neonicotinoids have become the fastest-growing class of insecticides because of their efficiency in targeting pests. They work by strongly binding to nicotinic acetylcholine receptors (nAChRs) in the central nervous system of insects, leading to receptor blockage, paralysis, and death. Despite their selectivity for insects, these substances may be hazardous to non-target creatures, including earthworms. Although earthworms may be invasive in some regions like north America, they contribute to the development of soil structure, water management, nutrient cycling, pollution remediation, and cultural services, positively impacting the environment, particularly in the soil ecosystem. Thus, this study aimed to develop a novel earthworm behavior assay since behavior is a sensitive marker for toxicity assay, and demonstrated its application in evaluating the toxicity of various neonicotinoids. Here, we exposed Eisenia fetida to 1 and 10 ppb of eight neonicotinoids (acetamiprid, clothianidin, dinotefuran, imidacloprid, nitenpyram pestanal, thiacloprid, thiametoxam, and sulfoxaflor) for 3 days to observe their behavior toxicities. Overall, all of the neonicotinoids decreased their locomotion, showed by a reduction of average speed by 24.94-68.63% and increment in freezing time movement ratio by 1.51-4.25 times, and altered their movement orientation and complexity, indicated by the decrement in the fractal dimension value by 24-70%. Moreover, some of the neonicotinoids, which were acetamiprid, dinotefuran, imidacloprid, nitenpyram, and sulfoxaflor, could even alter their exploratory behaviors, which was shown by the increment in the time spent in the center area value by 6.94-12.99 times. Furthermore, based on the PCA and heatmap clustering results, thiametoxam was found as the neonicotinoid that possessed the least pronounced behavior toxicity effects among the tested pesticides since these neonicotinoid-treated groups in both concentrations were grouped in the same major cluster with the control group. Finally, molecular docking was also conducted to examine neonicotinoids' possible binding mechanism to Acetylcholine Binding Protein (AChBP), which is responsible for neurotransmission. The molecular docking result confirmed that each of the neonicotinoids has a relatively high binding energy with AChBP, with the lowest binding energy was possessed by thiametoxam, which consistent with its relatively low behavior toxicities. Thus, these molecular docking results might hint at the possible mechanism behind the observed behavior alterations. To sum up, the present study demonstrated that all of the neonicotinoids altered the earthworm behaviors which might be due to their ability to bind with some specific neurotransmitters and the current findings give insights into the toxicities of neonicotinoids to the environment, especially animals in a soil ecosystem.

Toxicological approaches as tool to assess the effects of a mixture of photocatalytic degradation products originated from the unregulated neonicotinoid acetamiprid employing a terrestrial organism (Eisenia andrei)

Acetamiprid (ACT) has been detected in several water sources in Latin America. The presence of its degradation products in the environment is not negligible and transformation products (TPs) significantly contribute to environmental health risks. Although advanced oxidative processes are promising for the treatment of this neocotinoid, effects of these are still unknown. In this context, the effects of a mixture of photocatalytic degradation products resulting from an ACT treatment for 90 min employing TiO2/UV on cytotoxicity and oxidative stress parameters in Eisenia andrei earthworms in acute and chronic experiments using typical Latin American soil were assessed. Acute contact tests were performed (72 h) using a filter paper moistened with an ACT solution and a chronic test was performed using Oxisoil (200 g) moistened with an ACT solution for 45 days. Catalase (CAT) and glutathione-S-transferase (GST) activities, reduced glutathione (GSH) levels and cytotoxicity (cellular eleocyte and amoebocyte assessments) were investigated. Over 75 % of ACT was degraded within the first 15 min of treatment, with levels below the limit of detection after 60 min. The acute test revealed greater cytotoxic effects associated with the effluents treated for T0 and T15 min, with decreased cell density noted after 48 h of exposure, in addition to CAT induction (in all treatments) and GST induction following T0, T15 and T90 min exposures. Concerning the chronic assay, decreases in cell density (T0, T15, T60 and T90 min) and viability (T0, T60 and T90 min) were observed after 45 days, in addition to induced CAT activity following T0, T15 and T60 exposures and GST induction following the T60 min exposure. Reduced glutathione levels were unaltered, comprising the least sensitive biomarker among the investigated parameters to the treated effluent exposures. The mixture of ACT degradation products can cause toxic effects to non-target organisms, despite parent compound degradation, alerting for the need for ecotoxicological tests to prove decreased effluent toxicity, in addition to the improvement of degradation techniques.

Screening of Toxic Effects of Neonicotinoid Insecticides with a Focus on Acetamiprid: A Review

Recently, neonicotinoids have become the fastest-growing class of insecticides in conventional crop protection, with extensive usage against a wide range of sucking and chewing pests. Neonicotinoids are widely used due to their high toxicity to invertebrates, simplicity, flexibility with which they may be applied, and lengthy persistence, and their systemic nature ensures that they spread to all sections of the target crop. However, these properties raise the risk of environmental contaminations and potential toxicity to non-target organisms. Acetamiprid is a new generation insecticide, which is a safer alternative for controlling insect pests because of its low toxicity to honeybees. Acetamiprid is intended to target nicotinic acetylcholine receptors in insects, but its widespread usage has resulted in negative impacts on non-target animals such as mammals. This review summarizes in vivo and in vitro animal studies that investigated the toxicity of specific neonicotinoids. With summarized data, it can be presumed that certain concentrations of neonicotinoids in the reproductive system cause oxidative stress in the testis; spermatogenesis disruption; spermatozoa degradation; interruptions to endocrine function and Sertoli and Leydig cell function. In the female reproductive system, acetamiprid evokes pathomorphological alterations in follicles, along with metabolic changes in the ovaries.

Immunomodulatory effect of imidacloprid on macrophage RAW 264.7 cells

The neonicotinoid imidacloprid was promoted in the market because of widespread resistance to other insecticides, plus its low mammalian impact and higher specific toxicity towards insects. This study aimed to evaluate the immunomodulatory effect of imidacloprid on macrophages. RAW 264.7 cells were incubated to 0-4000mg/L of imidacloprid for 24 and 96h. Imidacloprid presented a concentration-dependent cytotoxicity after 24h and 96h incubation for MTT reduction (3-(4,5-dimethyl-thiazol-2-yl)-2,5-diphenyltetrazolium bromide) (EC₅₀ 519.6 and 324.6mg/L, respectively) and Neutral Red (3-amino-7-dimethylamino-2-methylphenazine hydrochloride) assays (EC₅₀ 1139.0 and 324.2mg/L, respectively). Moreover, imidacloprid decreased the cells' inflammatory response and promoted a mitochondrial depolarization. The complex II and succinate dehydrogenase (SDH) activities in RAW 264.7 cells incubated with imidacloprid increased more at 24h. These results suggest that imidacloprid exerts an immunomodulatory effect and mitochondria can act as regulator of innate immune responses in the cytotoxicity mediated by the insecticide in RAW 264.7 cells.

Effects of a Neonicotinoid on Indigenous Earthworm Perionyx excavatus Biochemical and Histopathological Alterations

Acetamiprid is a broad-spectrum insecticide, belonging to the neonicotinoid compounds group, which has been extensively applied throughout the globe. Recently, indiscriminate use of these compounds was reported to cause fatal impacts on non-targeted soil organisms. Hence, the present study aimed to examine the impact of acetamiprid on Indian indigenous earthworm, Perionyx excavatus. Acute toxicity revealed an LC₅₀ concentration of 0.25 µg/cm² for filter paper test/72 h and 400 µg/kg for artificial soil test/14 days. Oxidative stress (ROS) and various biomarkers including superoxide dismutase, catalase, glutathione S-transferase, malondialdehyde content and DNA damage were measured. The results of the biomarker responses confirmed the acetamiprid exposure can cause toxicity to P. excavatus. In addition, cell density (20 × 10² cell mL/mg) and cell viability (40%) were significantly (p < 0.05) reduced. Further, the ecotoxicological assessment made through this study can be utilized as good evidence to toxicity of neonicotinoids to non-targeted indigenous organisms.

Degradation of imidacloprid and acetamiprid in tea (Camellia sinensis) infusion by ultraviolet light irradiation

The degradation of imidacloprid and acetamiprid in tea infusion by ultraviolet (UV) light irradiation was investigated in this study. Results showed that the influence of UV light irradiation on the quality of tea infusion was controllable and UV light irradiation was effective on the degradation of both pesticides. The maximum removal rates were 75.2% for imidacloprid and 17.6% for acetamiprid after irradiation (650 µW/cm,² 120 min). The degradation of both pesticides followed the first-order kinetics model. Three degradation products were identified for imidacloprid and one for acetamiprid based on liquid chromatography-tandem mass spectrometry analysis. The degradation pathway of imidacloprid involved in the cleavage of C-C bond with the loss of nitro group followed by the hydrogenation, oxidation and hydrolysis, while the degradation of acetamiprid involved in the oxidation at the chlorine atom with the bonding of C atoms at positions 1 and 4 on the pyridine ring. Simultaneously, the toxicity of both pesticides was mitigated by UV light irradiation according to LO2 cell toxicity evaluation. The study provided a low-cost and effective way to reduce imidacloprid and acetamiprid from tea infusion, and it has the potential to be applied to the ready-to drink tea beverage production in industrial scale.

Pesticides in honey: bibliographic and bibliometric analysis towards matrix quality for consumption

Abstract Honey is a matrix noted for its wide consumption as a sweetener and its anti-inflammatory, antioxidant, and antimicrobial properties; however, its physicochemical quality can be compromised by the presence of toxicants such as pesticides. This review aims to gather recent information on pesticides in honey from the approach to their detection, understanding, and adverse effects on human health. A bibliographic and bibliometric analysis was carried out in academic databases limited to the last five and thirty years, respectively, comprising the keywords “honey”, “pesticides” and their types of pesticides or the agrochemical compound directly. It was found that there are about 30 pesticides detected in honey, in which organochlorine, organophosphate, and neonicotinoid compounds stood out for their concentrations concerning Maximum Residue Levels (MRL). Their physicochemical alteration was not well explored beyond slight variations in brightness and manganese concentration, and its consumption may have repercussions on human reproductive health. It was also determined that there was limited development on the scientific subject seeing that it is important to explore and investigate more on the issue due to the great impact of honey as a product of high consumption at a global level.

The Characteristics and Potential Risks of Neonicotinoid Residues in Soils of Different Types of Land Use in Hangzhou

Due to the wide existence of neonicotinoid insecticides (neonics) and their potential impact on ecosystems and human health, they have received special attention in recent years. Soil is not only a sink of neonics but also a source of neonics, so it plays a key role in the ubiquity of neonics in the environment. The purpose of this research was to compare neonics residues in soils of different types of land use and estimate their exposure to different populations via ingestion. A total of 130 soil samples from six different types were collected. The concentrations of seven neonics in soil were simultaneous determined using isotope-dilution ultra-performance liquid chromatography-tandem mass spectrometry. The results showed that at least one neonic was analyzed in all samples. The highest average concentration was 3.42 ng/g (clothianidin), followed by 3.39 ng/g (thiamethoxam), 3.06 ng/g (acetamiprid), 2.84 ng/g (imidacloprid), 2.66 ng/g (nitenpyram), 2.43 ng/g (thiacloprid), and 1.89 ng/g (dinotefuran). IMI and ACE were the most commonly found neonics in soil. The neonic levels in different soils varied significantly. The integrated neonic residue in cropland was much higher than that in other types of land. The risk assessment revealed that the average daily dose (ADD) through ingestion contact with soil was acceptable to children and adults. With the increasing evidence that neonics could cause a variety of toxic effects on mammals and humans, ingestion exposure caused by neonics in soil should also receive continuous attention in future studies.

Acetamiprid fate in a sandy loam with contrasting soil organic matter contents: A comparison of the degradation, sorption and leaching of commercial neonicotinoid formulations

The impacts of neonicotinoids have generally focussed on the responses of the pure active ingredient. Using a selection of two commercial formulations and the active ingredient, we ran three laboratory studies using ¹⁴C-labelled acetamiprid to study the leaching, sorption and mineralisation behaviours of the commercially available neonicotinoid formulations compared to the pure active ingredient. We added ¹⁴C-spiked acetamiprid to a sandy loam soil that had received long-term additions of farmyard manure at two rates (10 t/ha/yr and 25 t/ha/yr) and mineral fertilisers, as a control. We found significant differences in acetamiprid mineralisation across both the SOM and chemical treatments. Sorption was primarily impacted by changes in SOM and any differences in leachate recovery were much less significant across both treatment types. The mineralisation of all pesticide formulations was comparatively slow, with <23 % of any given chemical/soil organic matter combination being mineralised over the experimental period. The highest mineralisation rates occurred in samples with the highest soil organic matter levels. The results also showed that 82.9 % ± 1.6 % of the acetamiprid applied was leached from the soil during repeated simulated rainfall events. This combined with the low sorption values, and the low rates of mineralisation, implies that acetamiprid is highly persistent and mobile within sandy soils. As a highly persistent neurotoxin with high invertebrate selectivity, the presence of neonicotinoids in soil presents a high toxicology risk to various beneficial soil organisms, including earthworms, as well as being at high risk of transfer to surrounding watercourses.

Ecological risk assessment and environment carrying capacity of soil pesticide residues in vegetable ecosystem in the Three Gorges Reservoir Area

Soil contamination by pesticide residues has become an increasing concern of ecological protection. However, the soil environmental carrying capacity (SECC) of pesticide residues in agricultural ecosystems was limited studied. Based on the concept of ecological risk assessment, a modified system on the environment carrying capacity was proposed for estimate SECC of pesticide residues in agricultural soils. Subsequently, the assessment on ecological risk and SECC of soil pesticide residues in vegetable ecosystem were performed in the Three Gorges Reservoir Area (TGRA). In 201 topsoil samples, 62.1% of the pesticide compounds were detected over limit of quantitation, and exhibit a high proportion of multiple pesticide contamination. Pyrethroid insecticides and herbicide glyphosate showed most frequent occurrence and high levels. The SECC of the TGRA varies with the limit standard, annual cumulative amount and risk quotient of each pesticide contaminant in soils. Except that fenpropathrin has exceeded SECC, chlorfenapyr, β-cyfluthrin and glyphosate posed the greatest threat to SECC in the next 50 years. Additionally, ecological risks by pesticide residues in vegetable ecosystem can be affected by various planting activities. These results will contribute to guide the rational application of pesticides and control soil environmental risks, thereby achieving the agricultural green development in the TGRA.

Comparative study of neonicotinoid insecticides (NNIs) and NNI-Related substances (r-NNIs) in foodstuffs and indoor dust

Comparative studies of neonicotinoid insecticides (NNIs) and NNI-related substances (r-NNIs) in foodstuffs and indoor dust are rare. Herein, we investigated the feature fragmentations of nine NNIs in high-energy collision dissociation cells via high-resolution orbitrap mass spectrometry and observed that NNIs can consistently generate several feature fragments (e.g., C6H5NCl+, C4H3NSCl+, and C6H5NF3+). Consequently, NNIs and r-NNIs were comprehensively (targeted, suspect, and feature fragment-dependent) detected in 107 foodstuff and 49 indoor dust samples collected from Nanjing City (eastern China). We fully or tentatively identified 9 target NNIs and 5 r-NNIs in these samples. NNIs and r-NNIs were detected in 93.5% of the analyzed foodstuff samples, and high concentrations were detected in vegetables (mean: 409 ng/g wet weight [ww]) and fruits (127 ng/g ww). Regarding indoor dust, imidacloprid and acetamiprid exhibited extremely high detection frequencies and contamination levels, and the highest mean concentrations of NNIs and r-NNIs were detected in dormitory samples. Based on the NNI and r-NNI concentrations in the analyzed samples, the mean estimated daily intake values for Chinese adults and children via dietary intake and dust ingestion were 2080-8190 ng/kg bw/day and 378-2680 pg/kg bw/day, respectively.

Recent Advances in Plant Metabolomics: From Metabolic Pathways to Health Impact

In the past decade, technological development allowed a rapid advance on several OMIC approaches, metabolomics was no exception [...]

Statement on the active substance acetamiprid

Acetamiprid is a pesticide active substance with insecticidal action currently under the third renewal (AIR3) of the Commission implementing regulation (EU) No 844/2012. Following concerns that this substance may pose high risks to humans and the environment, the French authorities asked the Commission to restrict its uses under Article 69 of Regulation (EC) No 1107/2009. To support this request, competent Authorities from France cited a series of literature papers investigating its hazards and/or exposure to humans and the environment. Consequently, the EFSA PPR Panel was mandated to advise on the likelihood that body of evidence would constitute proof of serious risks to humans or the environment. Therefore, the EFSA PPR Panel evaluated the likelihood of these studies indicating new or higher hazards and exposure to humans and the environment compared to previous EU assessments.A stepwise methodology was designed, including: (i) the initial screening; (ii) the data extraction and critical appraisal based on the principles of OHAT/NTP; (iii) the weight of evidence, including consideration of the previous EU assessments; (iv) the uncertainty analysis, followed, whenever relevant, by an expert knowledge elicitation process. For human health, no conclusive evidence of higher hazards compared to previous assessment was found for genotoxicity, developmental toxicity, neurotoxicity including developmental neurotoxicity and immunotoxicity. However, due to the lack of adequate assessment of the current data set, the PPR Panel recommends conducting an assessment of endocrine disrupting properties for acetamiprid in line with EFSA/ECHA guidance document for the identification of endocrine disruptors. For environment, no conclusive, robust evidence of higher hazards compared to the previous assessment was found for birds, aquatic organisms, bees and soil organisms. However, the potential of high inter-species sensitivity of birds and bees towards acetamiprid requires further consideration.

Facile Detection and Quantification of Acetamiprid Using a Portable Raman Spectrometer Combined with Self-Assembled Gold Nanoparticle Array

Rapid and facile determination of pesticides is critically important in food and environmental monitoring. This study developed a self-assembled gold nanoparticle array based SERS method for highly specific and sensitive detection of acetamiprid, a neonicotinoid pesticide that used to be difficult in SERS analysis due to its low affinity with SERS substrates. SERS detection and quantification of acetamiprid was conducted with self-assembled gold nanoparticle arrays at the interface of chloroform and water as the enhancing substrate. Since targets dissolved in chloroform (organic phase) also have access to the hot-spots of Au NP array, the developed method exhibited good sensitivity and specificity for acetamiprid determination. Under the optimal conditions, SERS intensities at Raman shifts of 631 cm−1 and 1109 cm−1 displayed a good linear relationship with the logarithm concentration of acetamiprid in the range of 5.0 × 10−7 to 1.0 × 10−4 mol/L (0.11335 ppm to 22.67 ppm), with correlation coefficients of 0.97972 and 0.97552, respectively. The calculated LOD and LOQ of this method were 1.19 × 10−7 mol/L (0.265 ppb) and 2.63 × 10−7 mol/L (0.586 ppb), respectively, using SERS signal at 631 cm−1, and 2.95 × 10−7 mol/L (0.657 ppb) and 3.86 × 10−7 mol/L (0.860 ppb) using SERS signal at 1109 cm−1, respectively. Furthermore, the developed SERS method was successfully applied in determining acetamiprid on the surface of apple and spinach. This method offers an exciting opportunity for rapid detection of acetamiprid and other organic pesticides considering its advantages of simple preparation process, good specificity and sensitivity, and short detection time (within 1 h).

Ecotoxicological effects of commercial herbicides on the reproductive system of aquatic arthropod Limnocoris submontandoni (Hemiptera: Naucoridae)

Worldwide, conventional agriculture makes extensive use of pesticides. Although the effects of herbicides are relatively well known in terms of environmental impacts on non-target organisms, there is very little scientific evidence regarding the impacts of herbicide residues on aquatic arthropods from tropical conservation areas. This study evaluates for the first time the toxicity of the herbicides ametryn, atrazine, and clomazone on the aquatic insect Limnocoris submontandoni (Hemiptera: Naucoridae). The lethal concentration (LC50) of herbicides was evaluated for these insects, as well as the effect of the herbicides on the insects' tissues and testicles. The estimated LC50 was 1012.41, 192.42, and 46.09 mg/L for clomazone, atrazine, and ametryn, respectively. Spermatocyte and spermatid changes were observed under the effect of atrazine, and effects on spermatogenesis were observed for some concentrations of clomazone, with apparent recovery after a short time. Our results provide useful information on the effects of herbicide residues in aquatic systems. This information can help minimize the risk of long-term reproductive effects in non-target species that have been previously overlooked in ecotoxicology studies.

Chronic effects of clothianidin to non-target soil invertebrates: Ecological risk assessment using the species sensitivity distribution (SSD) approach

This study aimed to assess the chronic toxicity and risk of clothianidin in a seed dressing formulation to non-target soil invertebrates. The toxicity assays were performed with two oligochaetes (earthworms Eisenia andrei and enchytraeids Enchytraeus crypticus) and three collembolans (Folsomia candida, Proisotoma minuta and Sinella curviseta) species following ISO protocols. Risk assessment (via Hazard Quotient approach - HQ) was based on the hazardous concentrations for 95% of the species (HC₅), derived from chronic Species Sensitivity Distributions (SSD) for clothianidin, and on its predicted environmental concentrations (PEC). Four SSD scenarios were generated with literature and/or this study data, following different data selection criteria (i.e., general, only data from tests using similar formulations, similar soils, or identical soil/formulation). In our experiments, a higher clothianidin toxicity (EC₅₀-based) was found for collembolans (varying from 0.11 to 0.28 mg kg^-1 between species) followed by the earthworms (4.35 mg kg^-1), while the enchytraeids were the least sensitive (33.5 mg kg^-1). HQ indicated a significant risk of clothianidin to soil invertebrates because the estimated PEC were at least 16.6 times higher than HC₅ and are expected to affect the whole group of collembolans. Despite the criteria for data inclusion have influenced the HC₅ values, no substantial changes were observed for the risk outcomes. To our knowledge, this is the first study assessing the chronic ecological risk of clothianidin to beneficial soil fauna based on a probabilistic SSD approach. Data from this study can help to derive more reliable protection thresholds for clothianidin in soils.

Ecological risk assessment of pesticide residues in soils from vegetable production areas: A case study in S-Nepal

Pesticides pose a serious risk to ecosystems. In this study, we used European Food Safety Authority methods, such as risk quotient (RQ) and toxicity exposure ratios (TER), to assess the potential ecological risks of 15 pesticide residues detected in agricultural soils in the Gaidahawa Rural Municipality of Nepal. The mean and maximum concentrations of the detected pesticide residues in the soil were used for risk characterization related to soil organisms. RQ_mean, TER_mean and RQ_maximum, TER_maximum were used to determine general and the worst-case scenarios, respectively. Of all the detected pesticides in soils, the no observed effect concentration (NOEC) for 27% of the pesticides was not available in literature for the tested soil organisms and their TER and RQ could not be calculated. RQ threshold value of ≥1 indicates high risk for organisms. Similarly, TER threshold value of ≥5, which is acceptable trigger point value for chronic exposure, indicates an acceptable risk. The results showed that the worst-case scenario (RQ_maximum) indicated a high risk for soil organisms from chlorpyrifos [RQ_maximum > 9 at depths (cm) of 0-5, 15-20 and 35-40 soil layer]; imidacloprid (1.78 in the 35-40 cm soil layer) and profenofos (3.37 in the 0-5 cm and 1.09 in the 35-40 cm soil layer). Likewise, for all the soil depths, the calculated TER for both the general and worst-case scenarios for chlorpyrifos ranged from 0.37 to 3.22, indicating chronic toxicity to F. candida. Furthermore, the risk of organophosphate pesticides for soil organisms in the sampling sites was mainly due to chlorpyrifos, except for two study sites where the risk was from profenofos. Ecological risk assessment (EcoRA) of the pesticide use in the study area indicated that the EFSA soil organisms were at risk at some of the localities where farmers practiced conventional farming.

Occurrence and distribution of neonicotinoids and characteristic metabolites in paired urine and indoor dust from young adults: Implications for human exposure

Neonicotinoid insecticides (NEOs) are widely used for pest control worldwide. The profile of NEOs in paired urine and indoor dust has not yet been reported in China. In this study, 40 paired samples (i.e., 160 urine and 40 indoor dust) were collected from university students and dormitories from Guangzhou City of China to measure the concentrations of six NEOs and their three metabolites. Target analytes were frequently detected in paired urine (81%-98%) and indoor dust (75%-95%) samples, with median concentrations ranging from 0.02 [specific gravity (SG) adjusted: 0.02] to 2.08 (SG-adjusted: 2.38) ng/mL in urine and from 0.05 to 2.74 ng/g in indoor dust. 5-Hydroxy-imidacloprid was predominant in urine, while N-desmethyl acetamiprid was predominant in indoor dust samples, accounting for 56% and 37%, respectively. 1-Methyl-3-(tetrahydro-3-furylmethyl) urea, a dinotefuran degradate, was measured for the first time in indoor dust, with the median level of 1.02 ng/g. Significant gender-related differences (p < 0.05) in the urinary concentrations of most NEOs were found. We calculated the estimated daily intake (EDI) of target compounds from urine and indoor measurements. The EDIs of target analytes varied among all urine and indoor dust samples, with median values ranging from 0.51 (SG-adjusted: 0.56) to 51.6 (SG-adjusted: 52.8) ng/kg bw/day and from 0.04 to 2.10 pg/kg bw/day, respectively. Moreover, the median EDIs_urine of most target analytes in females were significantly higher than (p < 0.05) those in males. The median EDIs_dust of target compounds in dust from female dormitories were slightly higher than that in dust from male dormitories. These findings indicated that females were more exposed to NEO than males. Thus, the potential health risks of exposure to NEOs and their metabolites in female adults should be addressed in future studies. To our knowledge, this study is the first to report the profiles of NEOs and their metabolites in paired urine and indoor dust samples from young adults in China.

Insights into the degradation and toxicity difference mechanism of neonicotinoid pesticides in honeybees by mass spectrometry imaging

Honeybees are essential for the pollination of a wide variety of crops and flowering plants, whereas they are confronting decline around the world due to the overuse of pesticides, especially neonicotinoids. The mechanism behind the negative impacts of neonicotinoids on honeybees has attracted considerable interest, yet it remains unknown due to the limited insights into the spatiotemporal distribution of pesticides in honeybees. Herein, we demonstrated the use of matrix-assisted laser desorption/ionization mass spectrometry imaging (MALDI-MSI) for the spatiotemporal visualization of neonicotinoids, such as N-nitroguanidine (dinotefuran) and N-cyanoamidine (acetamiprid) compounds, administered by oral application or direct contact, in the whole-body section of honeybees. The MSI results revealed that both dinotefuran and acetamiprid can quickly penetrate various biological barriers and distribute within the whole-body section of honeybees, but acetamiprid can be degraded much faster than dinotefuran. The degradation rate of acetamiprid is significantly decreased when piperonyl butoxide (PBO) is applied, whereas that of dinotefuran remains almost unchanged. These two factors might contribute to the fact that dinotefuran affords a higher toxicity to honeybees than acetamiprid. Moreover, the toxicity and degradation rate of acetamiprid can be affected by co-application with tebuconazole. Taken together, the results presented here indicate that the discrepant toxicity between dinotefuran and acetamiprid does not lie in the difference in their penetration of various biological barriers of honeybees, but in the degradation rate of neonicotinoid pesticides within honeybee tissues. Moreover, new perspectives are given to better understand the causes of the current decline in honeybee populations posed by insecticides, providing guidelines for the precise use of conventional agrochemicals and the rational design of novel pesticide candidates.

Behavior of acetamiprid, azoxystrobin, pyraclostrobin, and lambda-cyhalothrin in/on pomegranate tissues

Pomegranate crop is affected by several insect pests and requires usage of a large number of pesticides, but the information on their behavior in pomegranate tissues is limited. A study was conducted to assess the behavior of acetamiprid, azoxystrobin, pyraclostrobin, and lambda-cyhalothrin in pomegranate fruits and leaves. The QuEChERS analytical method and LC-MS/MS and GC-MS were used for quantification of the analytes. The LOD (limit of detection) of acetamiprid, azoxystrobin, and pyraclostrobin was 0.0015 mg kg^-1 and lambda-cyhalothrin was 0.003 mg kg^-1. The respective LOQ (limit of quantification) was 0.005 and 0.01 mg kg^-1. The dissipation of the analytes best fitted into first-order rate kinetics and the half-lives of the chemicals in pomegranate fruits were 9.2-13 days and in the leaves were 13.5-17 days. In the pomegranate aril, the residue levels of acetamiprid, lambda-cyhalothrin, and pyraclostrobin were always < LOQ of these chemicals. Azoxystrobin was detected in pomegranate aril, and its residue was highest at 0.04 mg kg^-1 on the 10th day and reached < LOQ by the 25th day. The pre-harvest interval (PHI) required for acetamiprid, azoxystrobin, pyraclostrobin, and lambda-cyhalothrin at standard-dose treatment was 50, 58, 44, and 40 days, respectively. From double-dose treatment, the PHIs were 70, 75, 58, and 54 days, respectively. The pesticides used in this study were more persistent in the pomegranate leaves compared to the fruits. The outcome of this study can be incorporated into production of pomegranate fruits safe for consumption and to meet the domestic and export quality control requirements.

Bringing ecology into toxicology: Life-cycle toxicity of two neonicotinoids to four different species of springtails in LUFA 2.2 natural soil

Collembolans comprise one of the most abundant groups of soil invertebrates within the arthropods. The parthenogenetic species Folsomia candida (Willem, 1902) is the most well-studied representative, being used since the beginning of the 1960s as a model organism for assessing toxicity of chemicals in soil. In this paper we aimed at answering three questions by exposing four different species of springtails (F. candida, Folsomia fimetaria, Sinella curviseta and Heteromurus nitidus) to the neonicotinoids imidacloprid and thiacloprid: i) How representative as a model organism is F. candida for species of springtails that reproduce sexually? (ii) How suitable are other species of springtails to be used as model organisms for ecotoxicological testing? (iii) Is it possible to use the life history of these species to extrapolate the impact of neonicotinoids on the population level? Our results showed that F. candida is a good model organism, despite being the most sensitive species tested, when analysing both endpoints - survival and reproduction. The tests performed with S. curviseta and H. nitidus showed that they could be used as surrogates in ecotoxicity tests, and also to predict how their population might be affected after being exposed to chemicals. The adjustments made to the test performed with F. candida: introducing adults (20-22 days old) into the test jars and exposing them for 21 days instead of 28 days, proved to be as efficient as the standardized test guideline (OECD 232, 2009).

Effect of temperature on the toxicity of imidacloprid to Eisenia andrei and Folsomia candida in tropical soils

The influence of temperature on the chronic toxicity and risk of imidacloprid to soil non-target species was assessed in tropical soils. Earthworms Eisenia andrei and collembolans Folsomia candida were exposed to a tropical artificial soil (TAS) and two natural tropical soils from Brazil (Entisol and Oxisol) with increasing concentrations of imidacloprid under atmospheric temperatures of 20, 25 and 28 °C. The effect of temperature on the reproduction of both species was assessed through the number of juveniles and earthworm's growth, and the risk associated was estimated through the Toxicity-Exposure Ratio (TER). Toxicity of imidacloprid increased with temperature in all tested soils, being generally lower in TAS soil (EC₅₀s of 1.48, 0.66 and 0.40 mg kg^-1 for E. andrei and 0.3, 0.2 and 0.06 mg kg^-1 for F. candida at 20, 25 and 28 °C, respectively) compared to Entisol (EC₅₀s of 0.19, 0.03 and 0.14 mg kg^-1 for E. andrei and 0.04, 0.02, 0.01 mg kg^-1 for F. candida at 20, 25 and 28 °C, respectively) and Oxisol (EC₅₀s of 0.21, 0.07, 0.06 mg kg^-1 for E. andrei and 0.16, 0.09, 0.06 mg kg^-1 for F. candida at 20, 25 and 28 °C, respectively) within each temperature for both species. These values indicate that properties of TAS may not be representative of natural/local soils to adequately estimate the toxicity of pesticides to non-target soil species. At higher temperatures, the variability of imidacloprid toxicity between soils was lower, which suggests that the influence of soil properties on imidacloprid toxicity was overshadowed by temperature. TER values revealed that risk is also greater at higher temperatures. Data reported enforce the need for the inclusion of more realistic conditions in single-species tests in prospective risk assessment of pesticides to avoid underestimation of risk to non-target species.

Adsorption of acetamiprid, chlorantraniliprole and flubendiamide on different type of microplastics present in alluvial soil

The presence of microplastics (MPs) and their effects have been widely investigated in the aquatic environment, whereas the research done in the terrestrial environment is incomparably lacking. MPs are considered a pollutant in soil on agricultural land, where they can act as a vector for other pollutants, namely organic chemical compounds, such as pesticides. In soil, presence of MPs is affecting the growth and life of microorganisms in it. The interactions between two types of MPs and three pesticides in the mixture with alluvial soil were studied. Adsorption of acetamiprid, chlorantraniliprole and flubendiamide in concentrations of 1, 5 and 10 mg L^-1 onto polyester fibres and polypropylene particles of 0.5-1 mm size was studied at 1% and 5% (w/w) of their content in soil. Results showed that the adsorption of pesticides was dependent on their octanol/water partition coefficient, with the most highly adsorbed pesticide also being the most hydrophobic, regardless of the type and form of MPs. Adsorption of pesticides onto MP particles was confirmed in soil-MPs mixtures with 5% polypropylene and 5% polyester at all tested pesticides' concentrations, proving that MPs in soil systems act as carriers to pollutants. MPs in soil decreased the soil's intrinsic capacity to retain pesticides, indicating the possibility of a greater mobility of pesticides on MPs through the soil system.

Responses of detoxification enzymes in the midgut of Bombyx mori after exposure to low-dose of acetamiprid

Bombyx mori is an important economic insect. However, the environmental pollution caused by the widespread use of neonicotinoid insecticides has significantly affected the safe production of sericulture. In this paper, we determined the LC₅₀ of acetamiprid, a kind of neonicotinoid insecticides, to 5th instar silkworm larvae, examined its residues in hemolymph and midgut of silkworm after continuous exposure to low-dose of acetamiprid, and investigated the transcription level of detoxifying-related genes and the activity of detoxifying enzymes. The results showed that acetamiprid was highly toxic (24-h LC₅₀, 1.50 mg/L) to silkworm larvae. After continuous exposure to low-dose of acetamiprid (0.15 mg/L), the acetamiprid residue concentrations in hemolymph and midgut were 0.90 and 0.58 μg/mg, respectively, at 48 h, but all decreased at 96 h. At 24 h of acetamiprid exposure, the transcription levels of CYP4M5 and CYP6AB4 and the P450 enzyme activity were significantly enhanced. However, the transcription levels of CarE and CarE-11 and the activity of CarE enzymes were both inhibited by acetamiprid exposure. After 24 h-72 h of acetamiprid exposure, the transcription levels of GSTe3 and GSTd1 were significantly up-regulated, and the GST enzyme activity was also significantly elevated from 48 h to 96 h. Furthermore, the expression levels of FoxO, CncC and Keap1, the key upstream genes of detoxification enzymes, showed a similar trend as the GST genes. These results indicated that acetamiprid was reduced in midgut and the expression of GSTs was upregulated may via FoxO/CncC/Keap1 signaling pathway, which plays a key role in detoxification responses.

Toxicity in Neonicotinoids to Folsima candida and Eisenia andrei

We compared the toxicity of the neonicotinoids imidacloprid, thiacloprid, thiamethoxam, acetamiprid, and clothianidin in terms of the survival and reproduction of 2 species of soil invertebrates, Folsomia candida and Eisenia andrei. Tests were performed using LUFA 2.2 natural soil, following standard protocols aimed at answering 2 questions: 1) Is there a difference in the toxicity between pure compound and its formulation? and 2) Is there a difference in the sensitivity of the species exposed to the same compound? For E. andrei, formulations and pure compounds had similar toxicity to both endpoints tested. For F. candida, acetamiprid and imidacloprid had different toxicities, with acetamiprid being 4 times more toxic to survival (median lethal concentration [LC50] 0.12 mg active substance [a.s.]/kg dry soil) and imidacloprid being 4 times more toxic to reproduction of the springtail (median effect concentration [EC50] 0.25 mg a.s./kg dry soil) than their commercial formulations. The most toxic compound to E. andrei was acetamiprid (LC50 0.80 and EC50 0.35-0.40 mg a.s./kg), and the most toxic to F. candida was clothianidin (LC50 0.07 and EC50 0.05 mg a.s./kg). Estimated risk ratios indicated that only one application/yr of clothianidin in the formulation Poncho® may pose a threat to the populations of springtails and earthworms. Environ Toxicol Chem 2020;39:548-555. © 2019 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals, Inc. on behalf of SETAC.

Neonicotinoids and carbendazim in indoor dust from three cities in China: Spatial and temporal variations

Neonicotinoid insecticides (NNIs) are a relatively new class of insecticides, and carbendazim (CBDZ) is a representative antifungal biocide. The occurrence of them in indoor dust was not documented in China. In this study, 336 indoor dust samples were collected from 3 cities, including Taiyuan (October 2016), Wuhan (October 2016 and 2018), and Shenzhen (February 2019), located in North, Central, and South China, for determination of the residues of six NNIs, two of their metabolites, and CBDZ. Acetamiprid (ACE), imidacloprid (IMI), and CBDZ were found to be the major target analytes in dust samples from all selected cities with detection frequencies of 98.8%, 99.7%, and 95.2%, respectively. At least one target NNI was detected for all of the dust samples, with the median concentration of 25.8 ng/g for the imidacloprid-equivalent total neonicotinoids (IMI_eq: generated by the relative potency factor method), and the median for CBDZ was 35.8 ng/g. Higher levels of several NNIs and CBDZ were found in urban areas of Taiyuan and Wuhan than those in rural areas. A significant increase of the NNI residues was observed in dust of Wuhan from 2016 to 2018 (while not significant for CBDZ). Finally, the estimated daily intake (EDI) of IMI_eq and CBDZ for infants and toddlers were higher than that found in other age groups through dust ingestion, which indicated that infants and toddlers may be susceptible to current residue of NNIs and CBDZ in indoor dust, and dust ingestion of NNIs might be <1% of that reported for dietary intakes in China. This is the first study to report the residue levels of NNIs and CBDZ in dust samples from indoor environment in China.

Lethal and sublethal effects of acetamiprid on Eisenia andrei: Behavior, reproduction, cytotoxicity and oxidative stress

The neonicotinoid acetamiprid has been suggested as a worldwide substitute for organophosphates, due to its lower toxicity. The present study assessed several acetamiprid effects on Eisenia andrei earthworms in acute contact (ranging from 1.6 × 10^-5 to 0.16 μg cm^-2 acetamiprid), behavioral (0.1, 0.5, 1 mg kg^-1) and chronic (0.001, 0.01, 0.05 and 0.1 mg kg^-1 acetamiprid) assays carried out in natural soil. Reproduction, cytotoxicity (coelomocyte density and viability), immune cell typing (eleocytes and amoebocytes) and antioxidant defense system (glutathione (GSH), catalase (CAT) and glutathione S-transferase (GST)) responses were determined. The LC₅₀ in the acute contact test was calculated as 1.86 × 10^-2 μg cm^-2. Acetamiprid concentrations of 0.5 and 1 mg kg^-1 led to earthworm avoidance responses (NR = 61.09 ± 10.01%) and habitat loss (NR = 78.02 ± 12.03%), respectively. Reproduction was also affected, with a decreased number of cocoons and hatchlings per cocoon observed at 0.05 and 0.1 mg kg^-1. Amoebocytes were the predominant immune system cells during the 15th and 30th assay days, while eleocytes were the main cells observed at the 45th day. CAT activities on the 30th and 45th day of exposure were increased at the lowest acetamiprid concentrations (0.001 and 0.01 mg kg^-1) and decreased with increasing pesticide concentration (0.05 and 0.1 mg kg^-1). Maximum GST activities and GSH levels were noted at 0.01 mg kg^-1 acetamiprid. However, increasing concentrations led to GST inhibition, while GSH levels were maintained. A long-term acetamiprid exposure affected earthworm reproduction, behavior and immune and antioxidant systems, which could affect the ecological soil balance and, consequently, the entire food chain.

A nitrile-mediated aptasensor for optical anti-interference detection of acetamiprid in apple juice by surface-enhanced Raman scattering

Currently, the detection of pesticide is critical for food safety assurance, but it is still challenging due to the presence of biological interferents from complex food matrix. In this study, we developed an optical anti-interference surface-enhanced Raman scattering (SERS) aptasensor system for trace detection of acetamiprid. 4-(Mercaptomethyl) benzonitrile (MMBN) containing CN bond was used as Raman tag to provide a sharp peak (2227 cm^-1) in the Raman-silent spectral window (1800-2800 cm^-1) where no Raman signal existed for most of molecules. Gold nanoparticles (AuNPs) bonded with polyadenine (polyA)-mediated aptamer and Raman tag (MMBN-AuNPs-aptamer) was synthesized as Raman probe, while the complementary DNA (cDNA) conjugated with AgNPs-decorated silicon wafer (AgNPs@Si) was used as SERS substrate. As acetamiprid molecule could specifically combine with aptamer, preventing the formation of MMBN-AuNPs-aptamer-cDNA-AgNPs@Si (expressed as "Au-AgNPs@Si") hybrid through DNA sequence linking, Raman signal intensities of MMBN in Au-AgNPs@Si decreased when the concentration of acetamiprid increased. Under the optimum assay condition, the proposed method displayed a linear response for acetamiprid detection in the range of 25-250 nM with a low detection limit of 6.8 nM. Finally, the developed aptasensor was successfully used to determine acetamiprid content in apple juice. Accordingly, this novel anti-interference SERS aptasensor could be a promising acetamiprid sensor for food safety assurance.

Multi-level ecotoxicological effects of imidacloprid on earthworm (Eisenia fetida)

As a neurotoxic insecticide, imidacloprid (IMI) has been widely used for crop protection. However, continuous application of such pesticide in the environment may damage the non-target organisms in soil. In the present study, we aimed to investigate the effects of IMI on earthworms in terms of survival, avoidance behavior, reproduction, detoxification enzyme activity and gene expression using a systematic experimental approach. The results showed that the 14-day LC₅₀ value of IMI was 2.26 (2.09-2.43) mg a.i. kg^-1, and the 2-day AC₅₀ value (concentration inducing an avoidance rate of 50%) of IMI was 1.34 (1.02-1.91) mg a.i. kg^-1 to E. fetida. For reproduction, the 56-day EC₅₀ value of IMI was 0.87 (0.66-1.33) mg a.i. kg^-1 to E. fetida, and there was a positive correlation between the growth rate of earthworms and the number of juveniles in IMI treatments. Activities of carboxylesterase (CarE) and glutathione-S-transferases (GST) in earthworms were disturbed by IMI exposure. Moreover, effects of IMI on the CarE activity in earthworms were more severe and sensitive compared with the GST activity. The expressions of annetocin (ann) and calreticulin (crt) at the transcriptional level were decreased upon IMI exposure, reaching the lowest levels of 0.09 fold and 0.16 fold on day 7 and day 14, respectively. Transcriptionally controlled tumor protein (tctp), heat shock protein 70 (hsp70) and gst exhibited relatively obvious variations (up-regulation or down-regulation) when the exposure duration was extended. Taken together, these results comprehensively contributed to further understandings of the impacts of IMI on earthworms.

The risk of neonicotinoid exposure to shrimp aquaculture

Widespread agricultural use of systemic neonicotinoid insecticides has resulted in the unintended contamination of aquatic environments. Water quality surveys regularly detect neonicotinoids in rivers and waterways at concentrations that could impact aquaculture stock. The toxicity of neonicotinoids to non-target aquatic insect and crustacean species has been recognised, however, there is a paucity of information on their effect on commercial shrimp aquaculture. Here, we show that commercially produced shrimp are likely to be exposed to dietary, sediment and waterborne sources of neonicotinoids; increasing the risks of disease and accidental human consumption. This review examines indicators of sublethal neonicotinoid exposure in non-target species and analyses their potential usefulness for ecotoxicology assessment in shrimp. The identification of rapid, reliable responses to neonicotinoid exposure in shrimp will result in better decision making in aquaculture management.

Ecological risk assessment of pesticide residues in arable soils of the Czech Republic

Currently used pesticides (CUPs) represent one of the largest intentional inputs of potentially hazardous compounds into agricultural soils. Subsequently, pesticide residues (PRs) and their transformation products (TPs) persist in agricultural soils, occurring in diverse mixtures of compounds in various concentrations. In this study, measured environmental concentrations (MECs) of CUP residues and TPs, originated from previous growing seasons in agricultural soils of the Czech Republic, were used to characterize the environmental risk for agroecosystems. Toxicity exposure ratios (TERs) were calculated using predicted no-effect concentrations (PNECs) and MECs in order to identify single pesticide residues risk to in-soil invertebrates and microorganisms. Ecological risk assessment (ERA) for the mixtures of pesticide residues at each monitored site was assessed using a risk quotient (RQ) method and considering concentration addition among components in the mixtures. The compilation of ecotoxicity data to derived PNECs for in-soil organisms clearly showed data gaps mainly for triazine and chloroacetanilide TPs. In addition, chronic toxicity data for in-soil invertebrates at different trophic levels are not available for 30% of monitored CUPs. The ERA revealed that pesticide residues in soil pose a risk at 35% of the sites (RQ ≥ 1). Among measured pesticides, epoxiconazole, atrazine-2-hydroxy, carbendazim, dimoxystrobin, terbuthylazine and difenoconazole were the main contributors to the overall pesticide mixture toxicity. The measured levels of epoxiconazole together with the frequent presence in soils represent a risk for the agroecosystems. Further assessment of higher tiers of ERA should be considered and prioritized in the pesticides risk management.

Sub-lethal effects of six neonicotinoids on avoidance behavior and reproduction of earthworms (Eisenia fetida)

Avoidance behavior of earthworms (Eisenia fetida) against six neonicotinoids (NEOs) (acetamiprid, dinotefuram, clothianidin, thiacloprid, nitenpyram, imidacloprid) was studied following the protocol of ISO. The results showed obvious avoidance behavior of E. fetida against the tested insecticides, and the medium effective concentration for avoidance behavior (EC₅₀) of the six pesticides was 0.14, 0.55, 0.91, 7.87, 1.32 and 0.77 mg/kg, respectively. Compared to the acute toxicity, avoidance behavior was more sensitive as an indicator of soil contamination with NEOs. Chronic toxicity of above six NEOs to E. fetida was also evaluated; cocoon production, hatchability, cocoon weight and adult weight were all affected in the test. Cocoon production and hatchability were more sensitive than cocoon weight and adult weight. The reproduction of earthworms were significantly reduced with a 56 d half-maximal effective hatchability concentration (EC₅₀) of 0.37, 0.74, 1.30, 3.57, 1.20 and 0.70 mg/kg (acetamiprid, dinotefuram, clothianidin, thiacloprid, nitenpyram, imidacloprid), respectively. Most of the tested NEOs were highly toxic to E. fetida. Avoidance behavior and reproduction damage of E. fetida was observed at very low concentrations. The existing levels of pollution with NEOs in soil frequently exceed the lowest observed adverse effect concentrations, which are likely to have negative biological and ecological impacts on earthworms.

Evaluation of acetamiprid-induced genotoxic and oxidative responses in Eisenia fetida

As a novel neonicotinoids insecticide, acetamiprid has been widely used worldwide. In this study, a laboratory test was conducted to expose earthworms (Eisenia fetida) to artificial soil spiked with various concentrations of acetamiprid (0, 0.05, 0.10, 0.25 and 0.50 mg/kg of soil) respectively after 7, 14, 21 and 28 d. Reactive oxygen species (ROS) generation, antioxidant enzymes activity including superoxide dismutase (SOD), catalase (CAT) and glutathione S-transferases (GST), malondialdehyde (MDA) content, and DNA damage were determined in earthworms. The ROS level increased in varying degrees at most exposure concentrations. The SOD activity was not significantly affected. The CAT activity was increased in the beginning, then gradually suppressed and resumed to the control level at the end, with the maximum change (171%) occurred at 14 d for 0.05 mg/kg. The GST activity was induced at 7 d, and then inhibited, with the maximum change (67.6%) occurred at 14 d for 0.50 mg/kg. The MDA content had a tendency that increasing at the first and decreasing at the end. The olive tail moment (OTM) in comet assay reflected a dose-dependent relationship, and DNA damage initially increased and then decreased over time. The results suggest that the sub-chronic exposure of acetamiprid can cause oxidative stress and DNA damage of earthworm and change the activity of the anti-oxidant enzyme. In addition, ROS content and DNA damage can be good indicators for assessing environmental risks of acetamiprid in earthworms.