Moving past neonicotinoids and honeybees: A systematic review of existing research on other insecticides and bees

Synthetic pesticides (e.g. herbicides, fungicides and insecticides) are used widely in agriculture to protect crops from pests, weeds and disease. However, their use also comes with a range of environmental concerns. One key concern is the effect of insecticides on non-target organisms such as bees, who provide pollination services for crops and wild plants. This systematic literature review quantifies the existing research on bees and insecticides broadly, and then focuses more specifically on non-neonicotinoid insecticides and non-honeybees. We find that articles on honeybees (Apis sp.) and insecticides account for 80% of all research, with all other bees combined making up 20%. Neonicotinoids were studied in 34% of articles across all bees and were the most widely studied insecticide class for non-honeybees overall, with almost three times as many studies than the second most studied class. Of non-neonicotinoid insecticide classes and non-honeybees, the most studied were pyrethroids and organophosphates followed by carbamates, and the most widely represented bee taxa were bumblebees (Bombus), followed by leaf-cutter bees (Megachile) and mason bees (Osmia). Research has taken place across several countries, with the highest numbers of articles from Brazil and the US, and with notable gaps from countries in Asia, Africa and Oceania. Mortality was the most studied effect type, while sub-lethal effects such as on behaviour were less studied. Few studies tested how the effect of insecticides were influenced by multiple pressures, such as climate change and co-occurring pesticides (cocktail effects). As anthropogenic pressures do not occur in isolation, we suggest that future research also addresses these knowledge gaps. Given the changing global patterns in insecticide use, and the increasing inclusion of both non-honeybees and sub-lethal effects in pesticide risk assessment, there is a need for expanding research beyond its current state to ensure a strong scientific evidence base for the development of risk assessment and associated policy.

Association between urinary neonicotinoid insecticide levels and dyslipidemia risk: A cross-sectional study in Chinese community-dwelling elderly

Experimental evidence has demonstrated that neonicotinoids (NEOs) exposure can cause lipid accumulation and increased leptin levels. However, the relationship between NEOs exposure and dyslipidemia in humans remains unclear, and the interactive effects of NEOs and their characteristic metabolites on dyslipidemia remain unknown. We detected 14 NEOs and their metabolites in urine samples of 500 individuals (236 and 264 with and without dyslipidemia, respectively) randomly selected from the baseline of the Yinchuan community-dwelling elderly cohort (Ningxia, China). The NEOs and their metabolites were widely detected in urine (87.2-99.6 %) samples, and the median levels ranged within 0.06-0.55 μg/g creatinine. The positive associations and dose-dependent relationships of thiacloprid, imidacloprid-olefin, and imidacloprid-equivalent total with dyslipidemia were validated using restricted cubic spline analysis. Mixture models revealed a positive association between the NEOs mixture and dyslipidemia risk, with urine desnitro-imidacloprid ranked as the top contributor. The Bayesian Kernel Machine Regression models showed that the NEOs mixtures were associated with increased dyslipidemia when the chemical mixtures were ≥ 25th percentile compared to their medians, and desnitro-imidacloprid and imidacloprid-olefin were the major contributors to the combined effect. Given the widespread use of NEOs and the dyslipidemia pandemic, further investigations are urgently needed to confirm our findings and elucidate the underlying mechanisms.

Competitive Assay for the Ultrasensitive Detection of Organophosphate Pesticides Based on a Fiber-Optic Particle Plasmon Resonance Biosensor and an Acetylcholinesterase Binding Peptide

An acetylcholinesterase (AChE) binding-based biosensor was developed for the ultrasensitive detection of organophosphate (OP) pesticides. The biosensor integrates the technique based on fiber-optic particle plasmon resonance detection and a synthetic AChE binding peptide conjugated with gold nanoparticles on the optical fiber surface via an AChE competitive binding assay. The OP pesticides present in the solution hinder the binding of AChE to the peptide on the biosensor by competing for the binding sites present in AChE. The limit of detection obtained for parathion using this method was observed to be 0.66 ppt (2.3 pM). This method shows a wide linear dynamic range of 6 orders. Furthermore, the use of the AChE binding peptide in the biosensor can better discriminate OPs against carbamates by using only a single biosensor. The practical application of this method was tested using spiked samples, which yielded good recovery and reproducibility. The spiked sample required minimal pretreatment before analysis; hence, this biosensor may also be used in the field.

Effects of intensive agriculture and urbanization on water quality and pesticide risks in freshwater ecosystems of the Ecuadorian Amazon

The Ecuadorian Amazon has experienced a significant land use change due to the demographic increase and the expansion of the agricultural frontier. Such changes in land use have been associated to water pollution problems, including the emission of untreated urban wastewater and pesticides. Here we provide the first report on the influence of urbanization and intensive agriculture expansion on water quality parameters, pesticide contamination and the ecological status of Amazonian freshwater ecosystems of Ecuador. We monitored 19 water quality parameters, 27 pesticides, and the macroinvertebrate community in 40 sampling locations of the Napo River basin (northern Ecuador), including a nature conservation reserve and sites in areas influenced by African palm oil production, corn production and urbanization. The ecological risks of pesticides were assessed using a probabilistic approach based on species sensitivity distributions. The results of our study show that urban areas and areas dominated by African palm oil production have a significant influence on water quality parameters, affecting macroinvertebrate communities and biomonitoring indices. Pesticide residues were detected in all sampling sites, with carbendazim, azoxystrobin, diazinon, propiconazole and imidacloprid showing the largest prevalence (>80% of the samples). We found a significant effect of land use on water pesticide contamination, with residues of organophosphate insecticides correlating with African palm oil production and some fungicides with urban areas. The pesticide risk assessment indicated organophosphate insecticides (ethion, chlorpyrifos, azinphos-methyl, profenofos and prothiophos) and imidacloprid as the compounds posing the largest ecotoxicological hazard, with pesticide mixtures potentially affecting up to 26-29% of aquatic species. Ecological risks of organophosphate insecticides were more likely to occur in rivers surrounded by African palm oil plantations, while imidacloprid risks were identified in corn crop areas as well as in natural areas. Future investigations are needed to clarify the sources of imidacloprid contamination and to assess its effects for Amazonian freshwater ecosystems.

Residue behavior and efficacy of benzothiazole in grains under different fumigation conditions

BACKGROUND

Benzothiazole is a potential grain fumigant for Tribolium castaneum. However, its safety profile and suitable fumigation conditions remain unknown. We therefore investigated the insecticidal efficacy, accumulation and dissipation of benzothiazole in grains (wheat, corn and rice) under different temperatures.

RESULTS

We established a universal detection method (modified QuEChERS coupled with GC-MS/MS) of benzothiazole residues in three grains, which provided high linearity (R2  > 0.999), sensitivity (limits of detection = 0.001 mg/kg, limits of quantification = 0.002-0.005 mg/kg), accuracy (recoveries = 88.18-118.75%) and precision (relative standard deviations < 4.78%). The insecticidal efficacy order of benzothiazole was 30 ≥ 10 > 20 °C and corn > wheat > rice. Temperature positively affected the accumulation/dissipation rate of benzothiazole. Rice was the most easily accumulated and dissipated grain for benzothiazole residues, while corn accumulated benzothiazole more than wheat but less than rice, with dissipation slower than wheat and rice.

CONCLUSION

Our results provide important references for the application of benzothiazole and other fumigants. © 2023 Society of Chemical Industry.

Pesticide residues in honey bee (Apis mellifera) pollen collected in two ornamental plant nurseries in Connecticut: Implications for bee health and risk assessment

Honey bees (Apis mellifera L.) are one of the most important managed pollinators of agricultural crops. While potential effects of agricultural pesticides on honey bee health have been investigated in some settings, risks to honey bees associated with exposures occurring in the plant nursery setting have received little attention. We sought to identify and quantify pesticide levels present in honey bee-collected pollen harvested in two ornamental plant nurseries (i.e., Nursery A and Nursery B) in Connecticut. From June to September 2018, pollen was collected weekly from 8 colonies using bottom-mounted pollen traps. Fifty-five unique pesticides (including related metabolites) were detected: 24 insecticides, 20 fungicides, and 11 herbicides. Some of the pesticide contaminants detected in the pollen had not been applied by the nurseries, indicating that the honey bee colonies did not exclusively forage on pollen at their respective nursery. The average number of pesticides per sample was similar at both nurseries (i.e., 12.9 at Nursery A and 14.2 at Nursery B). To estimate the potential risk posed to honey bees from these samples, we utilized the USEPA's BeeREX tool to calculate risk quotients (RQs) for each pesticide within each sample. The median aggregate RQ for nurse bees was 0.003 at both nurseries, well below the acute risk level of concern (LOC) of ≥0.4. We also calculated RQs for larvae due to their increased sensitivity to certain pesticides. In total, 6 samples had larval RQs above the LOC (0.45-2.51), resulting from the organophosphate insecticide diazinon. Since 2015, the frequency and amount of diazinon detected in pollen increased at one of our study locations, potentially due to pressure to reduce the use of neonicotinoid insecticides. Overall, these data highlight the importance of considering all life stages when estimating potential risk to honey bee colonies from pesticide exposure.

Method validation for detection of afidopyropen and M440I007 in tea

BACKGROUND

Afidopyropen is a novel biorational insecticide for controlling piercing pests with great potential for application in tea gardens that can form the metabolite M440I007 when utilized for crops. However, because of a lack of analytical method for afidopyropen and M440I007 in tea, there is no means of monitoring the residues. Therefore, method development, validation and simultaneous determination of afidopyropen and M440I007 in fresh tea leaves, dried tea and tea infusion is of prime significance.

RESULTS

A TPT cartridge-based method was developed for the solid phase extraction of afidopyropen and M440I007 from tea matrices. Extraction and clean-up conditions, including the composition, volume and temperature of elutions, were optimized to achieve the best results. Both targets were extracted using water and acetonitrile, with a water:acetonitrile (v/v) ratio of 4:10 for fresh leaves and 8:10 for dried tea, which were then cleaned and analyzed using ultraperformance liquid chromatography-tandem mass spectrometry. Both analytes demonstrated excellent linearity with a correlation coefficient above 0.998. The optimized analytical method offered limits of quantifications of 0.005, 0.005 and 0.002 mg kg-1 (converted to dried tea) in fresh tea shoots, dried tea and tea infusion for both targets, respectively. Average recoveries of afidopyropen and M440I007 ranged from 79.0% to 101.5%, with relative standard deviations ≤ 14.7%.

CONCLUSION

The results showed that the method of determination for these insecticides in tea matrices was practical and efficient. © 2023 Society of Chemical Industry.

The effect of different decontamination processes on the residues of fipronil and its metabolites in chili fruits (Capsicum annuum L.)

Fipronil is a broad-spectrum phenyl pyrazole insecticide that has a high degree of environmental toxicity. Commonly available chilies in the market are treated with fipronil insecticides. Demand for insecticide-free chili has thus been increasing globally. This needs various sustainable and economical methods to remove insecticides from chilies. The present study examined the effectiveness of several cleaning methods to remove pesticide residues in chili fruits. A supervised field trial was conducted in randomized block design at Rajasthan Agricultural Research Institute, Durgapura, Jaipur, India. Chili samples were subjected to seven different household methods. The samples were extracted using the quick, easy, cheap, effective, rugged, and safe (QuEChERS) method. The residues were analyzed using a gas chromatograph-electron capture detector and confirmed by GC-MS. Of the seven methods, the acetic acid treatment removes the maximum residue effect of fipronil and its metabolites (desulfinyl [MB046513]), sulfide (MB045950), and sulfone (MB046136) on chili fruits. By contrast, the tap water treatment was the least effective. The Food Safety and Standards Authority of India (FSSAI) have set the maximum residue limit value of 0.001 mg kg-1 for fipronil on green chili.

Effiiency of the Essential Oil of Porophyllum linaria (Asteraceae) a Mexican Endemic Plant Against Sitophilus zeamais (Coleoptera: Curculionidae)

The insecticidal and repellent effect of essential oil isolated from fresh leaves of Porophyllum linaria on maize weevil was evaluated, as well as the effect on the grain germination after treated. In total, 28 constituents were identified by gas chromatography coupled with mass spectrometry accounting for 99.86% of whole essential oil. The main majority compounds were β-myrcene (41.94%), D-limonene (20.29%), and estragole (20.03%). Contact toxicity significantly increased with dose and time after treatment. With the 800 ppm (highest concentration), the mortality (%) obtained for the tenth and fifteenth day was 43 and 82%, respectively, whereas with 50 ppm (lowest concentration) 30% mortality was obtained at the end of the experiment (fifteenth day). At 15 d (end of the experiment), the LC50 y LC90 were obtained with values of 329.01 ± 44.35 y 1058.86 ± 117.76 ppm, respectively. For a concentration of 800 ppm, a selection index of zero was obtained, indicating the preference of the pest to the untreated maize (control). The maize grains germination test showed a significant reduction both in the length of hypocotyl and radicle of maize grain. So, in the highest dose, the hypocotyl and radicle length was 1.40 ± 0.34 and 9.14 ± 0.55 cm, respectively, whereas the control group registered 3.28 ± 0.39 and 13.02 ± 0.97 cm, respectively. This finding is promising since as it could result in the identification of botanical substances capable of suppressing maize weevil, Sitophilus zeamais development.

Validation of an HPLC-MS/MS method with QuEChERS extraction using isotopic dilution to analyze chlordecone in human serum

Until 1993, chlordecone (CLD) was extensively used in banana fields in French West Indies. In a previous study, CLD was detected in 90 % of Martinican and Guadeloupean adult's serum. In order to simplify the analyses of CLD in the serum, a new QuEChERS-HPLC-MS/MS method was implemented and validated by the Pasteur Institute of Guadeloupe (IPG). This method was validated with accuracy profiles according to the French Standard NF V03-110 plus the ISO 15189 and European guidelines. Linearity, repeatability, accuracy, intermediate precision, specificity, limit of detection (LOD), limit of quantification (LOQ) and uncertainty were determined. The accuracy profile allowed the method to be validated between 0.06  µg L-1 and 1.00  µg L-1 of serum. The LOD was 0.02  µg L-1, the LOQ was 0.06  µg L-1 and the uncertainty of the method was 21 %. A comparison of 49 serum samples between the IPG (LC-MS/MS) and the LEAE-CART (GC-HRMS) laboratories demonstrated that this new method can reliably determine CLD in human serum. Stability tests were performed and duration of the storage of raw samples and extracts before analysis by HPLC-MS/MS. Raw samples were stable after collection for at least one week at 5 °C or 25 °C and for at least 3 months at -20 °C. Extracts in acetonitrile were stable for at least 1 month at -20 °C. These stability results facilitate the daily use of the method. This method should help the entire population of Guadeloupe and Martinique by allowing a routinely analyzed for CLD and will be useful for future projects aimed at improving population health monitoring.

Residue dynamics and dietary risk assessment of new formulation of novaluron and lambda cyhalothrin on tomato

Presence of residues on food commodities is major bottleneck of insecticide use under good agricultural practices (GAPs). The use of less persistent with two different mode of action insecticide is novel approach of getting maximum insect control without developing insecticide resistance. Novaluron, an insect growth disruptor and lambda cyhalothrin, a nerve poison has been used widely for the management of lepidopteran pests. Dissipation and consumer risk analysis studies were carried out on a new combination product of novaluron and lambda cyhalothrin are used for control insects of tomato at recommended standard dose of 71 + 14 g/ha and double dose of 142 + 28 g/ha of active ingredients. Extraction and cleanup of sample residues was done using QuEChERS technique and analyzed in GC-ECD. The residues of novaluron were dissipated within 10 to 15 days, and the residues of lambda cyhalothrin were at 7 to 10 days, both at the standard and double the standard dose, following a first order reaction kinetics. Analysis of risk and hazard quotient revealed that the test insecticides do not pose any dietary risk to consumer as TMDI < MPI and HQ < 1.

Dust abraded from thiamethoxam-treated seed during sowing: Refining the risk assessment for native bees in Brazil

During sowing using pneumatic machinery, dust may be abraded from pesticide-treated seed and contaminate adjacent bee-attractive off-crop areas. This study quantified the risk to native bees of dust released during sowing of Brazilian crop seeds treated with a thiamethoxam formulation (Cruiser 350FS). To address toxicity to native bees, adult acute contact LD50 data for thiamethoxam were collated from the literature, a species sensitivity distribution generated, and the HD5 calculated. The LD50 HD5 was used to refine the default safety factor applied to the honeybee acute contact LD50 from 10 to 5.45 for thiamethoxam. Crop-specific abraded dust data (Heubach dust and Heubach AI) were generated for seeds treated with Cruiser 350FS sourced from on-farm and industrial facilities. The mean Heubach dust levels was ranked as cotton = maize > sunflower = soybean > drybean. There was no correlation between the measured residues of thiamethoxam (Heubach AI) and those estimated in dust based on the thiamethoxam content of Cruiser 350FS. A hazard quotient (HQ) for each crop (based on application rate, the default dust deposition factor, and the honeybee contact LD50/10) identified risks during sowing for all crops. Refinement of the application rate with the measured 90th percentile Heubach dust (assuming 100% thiamethoxam) resulted in sowing of industrially treated soybean and on-farm treated cotton being identified as risks. Further refinement using either the measured 90th percentile Heubach AI or the acute contact LD50 (HD5 ) resulted in sowing of all crops treated with Cruiser 350FS as being identified as low risk. Similar high quality seed treatment should be demonstrated for other formulations containing insecticides with high toxicity to bees. Data on dust drift from machinery and crops more representative of those in Brazil may allow further refinement of the default dust deposition value of 17% used in this study. Integr Environ Assess Manag 2023;19:1361-1373. © 2023 SETAC.

Synthesis of phosphate-functionalized magnetic porous organic polymer: A sorbent for sensitive determination of neonicotinoid insecticides in water and lemon juice

There is an urgent need to prepare advanced functional materials for extraction and enrichment of trace organic pollutants from different samples. In this work, two novel phosphate-functionalized porous organic polymers (DBP-POP and DPP-POP) were synthesized for the first time. Compared with phosphate-free counterpart, both phosphate-functionalized POPs showed excellent adsorption performance for the neonicotinoids due to the hydrogen bonding, π-π interaction and hydrophobic interaction. For ease of separating the sorbent from solution, magnetic DBP-POP (M-DBP-POP) was further prepared as sorbent to extract neonicotinoids from environmental water and lemon juice samples prior to their determination by high performance liquid chromatography-ultraviolet detection. Under optimal conditions, the detection limits (S/N = 3) of the method were 0.01-0.08 ng mL-1 for water and 0.03-0.10 ng mL-1 for lemon juice. The recoveries were in the range of 80.0% to 113.0% with relative standard deviation less than 10.6%. This work demonstrated the feasibility of phosphate-functionalized POPs for adsorption applications.

Cuticular property affects the insecticidal synergy of major constituents in thyme oil against houseflies, Musca domestica

Plant essential oils are intricate blends comprising predominantly of monoterpenes and some sesquiterpenes. These oils display diverse bioactivities against targeted organisms, often arising from complex interactions among their constituents, which may demonstrate synergistic or antagonistic effects. Despite their wide use as botanical insecticides, the mechanisms behind these interactions and their effects on bioactivity are poorly understood. This study investigated the synergistic interaction of thymol and p-cymene, two major constituents of Thymus vulgaris essential oil, on the larvae and adults of the housefly, Musca domestica. The results showed that p-cymene synergized the insecticidal activity of thymol in adult houseflies, but not in larvae. GC-MS analyses and bioassays indicated the increased cuticular penetration of thymol by p-cymene was the mechanism of synergy, which was observed only in the adults. Two potential routes were proposed: the expansion of the wetting area, or the disruption of cuticular integrity through dissolving the wax layer. The sequential application and large-volume treatment bioassay results suggested that the former was the more likely mechanism. Also, the hydrophobicity of the cuticle seemed critical for this stage-specific synergy. Wax-devoid adults failed to show synergistic toxicity, whereas artificially wax-coated larvae gained a synergistic effect. Overall, the findings provide insights into the synergistic mechanism of insecticidal activity of plant essential oils and suggest potential applications in developing effective strategies using penetration-enhancing synergists.

Transport of neonicotinoid insecticides in a wetland ecosystem: Has the cultivation of different crops become the major sources?

Extensive application of neonicotinoid insecticides (NNIs) in agricultural production has resulted in widespread contamination of multiple environmental media. To investigate the occurrence and fate of NNIs in the largest marsh distribution area in Northeast China, an integrated ecosystem covering farmlands, rivers, and marshes, referred to as the farmland-river-marsh continuum in this study, was chosen for soil, water, and sediment sampling. Five NNIs were detected, with imidacloprid (IMI), thiamethoxam (THM), and clothianidin (CLO) being the most frequently detected ones in different samples. Concentrations of target NNIs in soil, surface water, and sediment samples were 2.23-136 ng/g dry weight (dw), 3.20-51.7 ng/L, and 1.53-8.40 ng/g dw, respectively. In soils, NNIs were detected more often and at higher concentrations in upland fields, while the concentration of NNIs in the soybean-growing soils (71.5 ng/g dw) was significantly higher than in the rice-growing soils (18.5 ng/g dw) (p < 0.05). Total concentration of NNIs in surface water was lower in the Qixing River channel than inside the marsh, while that in sediments showed an opposite trend. Total migration mass of IMI from approximately 157,000 ha of farmland soil by surface runoff was estimated to be 2636-3402 kg from the application time to the sampling period. The storage of NNIs in sediments was estimated to range from 45.9 to 252 ng/cm². The estimated environmental risks, calculated as the risk quotients (RQs), revealed low risks to aquatic organisms (RQs <0.1) from the residual concentrations of NNIs in water.

Development and Validation of a New UFLC-MS/MS Method for the Detection of Organophosphate Pesticide Metabolites in Urine

To monitor human exposure to pesticides, experts commonly measure their metabolites in urine, particularly dialkyl phosphates (DAPs), which include diethyl phosphate (DEP), Diethyl thiophosphate (DETP), diethyl dithiophosphate (DEDTP), dimethyl phosphate (DMP), dimethyl thiophosphate (DMTP) and dimethyl dithiophosphate (DMDTP)to monitor the metabolites of organophosphates. These DAP metabolites are a urinary biomarker for assessing pesticide exposure and potential health risks. This study presented a new screening method combining ultrafast liquid chromatography with tandem mass spectrometry (UFLC-MS/MS) to detect six DAP metabolites in human urine. The study also compared standard sample extraction methods, namely, liquid-liquid extraction (LLE); quick, easy, cheap, effective, ruggedand safe (QuEChERS); and lyophilization. After a comprehensive analysis of the methods used to extract the analytes, including recovery rate, repeatability and reproducibility, the liquid-liquid extraction (LLE) method was found to be the best. It had a high recovery rate, was easy to handle, required less sample volume and had a short extraction time. Therefore, the LLE method was chosen for further analysis. The results showed excellent performance with high recoveries between 93% and 102%, precise repeatability (RSD) between 0.62% and 5.46% and acceptable reproducibility values (RSD) between 0.80% and 11.33%. The method also had limits of detection (LOD) ranging from 0.0201 ng/mL to 0.0697 ng/mL and limits of quantification (LOQ) ranging from 0.0609 ng/mL to 0.2112 ng/mL. Furthermore, the UFLC-MS/MS method was validated based on the SANTE guidance and successfully analyzed 150 urine samples from farmers and non-farmers. This validated method proved useful for biomonitoring studies focusing on OP pesticide exposure. It offers several advantages, such as a reduced need for samples, chemicals and materials, and a shorter analysis time. The method is sensitive and selective in detecting metabolites in human urine, making it a valuable approach for the practical and efficient assessment of pesticide exposure.

Neonicotinoids residues in cow milk and health risks to the Chinese general population

The application of neonicotinoid insecticides (NEOs) has increased dramatically in the world since being introduced in 1990s, yet the extent of human exposure and potential health risk is not fully unraveled. In this study, the residues were analyzed of 16 NEOs and their metabolites in 205 commercial cow milk samples circulating in Chinese market. All the milk samples contained at least one quantified NEO, and over 90% of samples contained a cocktail of NEOs. Acetamiprid, N-desmethyl acetamiprid, thiamethoxam, clothianidin and imidaclothiz were the most commonly detected analytes with detection frequencies of 50-88% and medians of 0.011-0.038 ng/mL in milk. Geographical origin was an important factor to influence abundances and levels of NEOs contamination in milk. Chinese local milk bore a significant higher risk from NEOs contamination than the imported milk. In China, the northwest presented the greatest concentrations of the insecticides relative to the north or south. Organic farming, ultra heat treatment and skimming could significantly reduce levels of NEOs contamination in milk. A relative potency factor method was used to evaluate estimated daily intake of NEO insecticides, and found the children had 3.5-5 times higher exposed risk via milk ingestion than the adults. The high frequency of NEOs detection in milk offers us a snapshot of the ubiquity of NEOs in milk, with possible health implications especially for children.

Imidacloprid exposure is detectable in over one third of wild bird samples from diverse Texas ecoregions

Avian decline is occurring globally with neonicotinoid insecticides posed as a potentially contributing factor. Birds can be exposed to neonicotinoids through coated seeds, soil, water, and insects, and experimentally exposed birds show varied adverse effects including mortality and disruption of immune, reproductive, and migration physiology. However, few studies have characterized exposure in wild bird communities over time. We hypothesized that neonicotinoid exposure would vary temporally and based on avian ecological traits. Birds were banded and blood sampled at eight non-agricultural sites across four Texas counties. Plasma from 55 species across 17 avian families was analyzed for the presence of 7 neonicotinoids using high performance liquid chromatography-tandem mass spectrometry. Imidacloprid was detected in 36 % of samples (n = 294); this included quantifiable concentrations (12 %; 10.8-36,131 pg/mL) and concentrations that were below the limit of quantification (25 %). Additionally, two birds were exposed to imidacloprid, acetamiprid (18,971.3 and 6844 pg/mL) and thiacloprid (7022.2 and 17,367 pg/mL), whereas no bird tested positive for clothianidin, dinotefuran, nitenpyram, or thiamethoxam, likely reflecting higher limits of detection for all compounds compared to imidacloprid. Birds sampled in spring and fall had higher incidences of exposure than those sampled in summer or winter. Subadult birds had higher incidences of exposure than adult birds. Among the species for which we tested more than five samples, American robin (Turdus migratorius) and red-winged blackbird (Agelaius phoeniceus) had significantly higher incidences of exposure. We found no relationships between exposure and foraging guild or avian family, suggesting birds with diverse life histories and taxonomies are at risk. Of seven birds resampled over time, six showed neonicotinoid exposure at least once with three showing exposures at multiple time points, indicating continued exposure. This study provides exposure data to inform ecological risk assessment of neonicotinoids and avian conservation efforts.

Pesticide residues in nectar and pollen of melon crops: Risk to pollinators and effects of a specific pesticide mixture on Bombus terrestris (Hymenoptera: Apidae) micro-colonies

Residues detected in pollen collected by honey bees are often used to estimate pesticide exposure in ecotoxicological studies. However, for a more accurate assessment of pesticides effect on foraging pollinators, residues found directly on flowers are a more realistic exposure approximation. We conducted a multi-residue analysis of pesticides on pollen and nectar of melon flowers collected from five fields. The cumulative chronic oral exposure Risk Index (RI) was calculated for Apis mellifera, Bombus terrestris and Osmia bicornis to multiple pesticides. However, this index could underestimate the risk since sublethal or synergistic effects are not considered. Therefore, a mixture containing three of the most frequently detected pesticides in our study was tested for synergistic impact on B. terrestris micro-colonies through a chronic oral toxicity test. According to the result, pollen and nectar samples contained numerous pesticide residues, including nine insecticides, nine fungicides, and one herbicide. Eleven of those were not applied by farmers during the crop season, revealing that melon agroecosystems may be pesticide contaminated environments. The primary contributor to the chronic RI was imidacloprid and O. bircornis is at greatest risk for lethality resulting from chronic oral exposure at these sites. In the bumblebee micro-colony bioassay, dietary exposure to acetamiprid, chlorpyrifos and oxamyl at residue level concentration, showed no effects on worker mortality, drone production or drone size and no synergies were detected when pesticide mixtures were evaluated. In conclusion, our findings have significant implications for improving pesticide risk assessment schemes to guarantee pollinator conservation. In particular, bee pesticide risk assessment should not be limited to acute exposure effects to isolated active ingredients in honey bees. Instead, risk assessments should consider the long-term pesticide exposure effects in both pollen and nectar on a range of bees that reflect the diversity of natural ecosystems and the synergistic potential among pesticide formulations.

Ecological threat caused by malathion and its chiral metabolite in a honey bee-rape system: Stereoselective exposure risk and the mechanism revealed by proteome

Honey bees play an important role in the ecological environment. Regrettably, a decline in honey bee colonies caused by chemical insecticides has occurred throughout the world. Potential stereoselective toxicity of chiral insecticides may be a hidden source of danger to bee colonies. In this study, the stereoselective exposure risk and mechanism of malathion and its chiral metabolite malaoxon were investigated. The absolute configurations were identified using an electron circular dichroism (ECD) model. Ultrahigh-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) was used for chiral separation. In pollen, the initial residues of malathion and malaoxon enantiomers were 3571-3619 and 397-402 μg/kg, respectively, and R-malathion degraded relatively slowly. The oral LD₅₀ values of R-malathion and S-malathion were 0.187 and 0.912 μg/bee with 5 times difference, respectively, and the malaoxon values were 0.633 and 0.766 μg/bee. The Pollen Hazard Quotient (PHQ) was used to evaluate exposure risk. R-malathion showed a higher risk. An analysis of the proteome, including Gene Ontology (GO), Kyoto Encyclopedia of Genes and Genomes (KEGG), and subcellular localization, indicated that energy metabolism and neurotransmitter transport were the main affected pathways. Our results provide a new scheme for the evaluation of the stereoselective exposure risk of chiral pesticides to honey bees.

Field Availability and Avoidance of Imidacloprid-Treated Soybean Seeds and Cotyledons by Birds

Treated seeds and their cotyledons can present a toxicological risk to seed-eating birds. To assess whether avoidance behavior limits exposure and consequently the risk to birds, three fields were sown with soybeans. Half of the surface of each field was sown with seeds treated with 42 g/100 kg seed of insecticide imidacloprid (T plot, treated) and the other half with seeds without imidacloprid (C plot, control). Unburied seeds were surveyed in C and T plots at 12 and 48 h post-sowing. Damaged seedlings were surveyed in C and T plots at 12 days post-sowing. The abundance and richness of birds was surveyed at the field level (without distinguishing between C and T plots) before, during, and after sowing, and 12 days post-sowing. Unburied seed density was higher in the headlands of the T plots than in the C plots, but did not differ between 12 and 48 h. The damage to cotyledons of seedlings was 15.4% higher in C plots than in T plots. The abundance and richness/ha of birds that eat seeds and cotyledons were lower after sowing, indicating a deterrent effect on birds by sowing imidacloprid-treated seeds. Although the variation in seed density over time does not allow solid conclusions to be drawn about the avoidance of seeds treated by birds, the seedling results suggest an aversive effect of imidacloprid-treated soybeans on birds. The dominant species was the eared dove (Zenaida auriculata), whose risk of acute poisoning by imidacloprid in soybean seeds and cotyledons was low, according to its toxicity exposure ratio, foraged area of concern, and foraged time of concern. Environ Toxicol Chem 2023;42:1049-1060. © 2023 SETAC.

Chemical monitoring and risk assessment of 56 pesticides in the Ave River and adjoining Atlantic coastline (Iberian Peninsula, Portugal)

The Ave basin (North Atlantic Ocean Ecoregion) is highly disturbed by anthropogenic activities. The amounts and distribution patterns of 56 priority pesticides (fungicides, herbicides, and insecticides) dissolved in the aqueous phase (DAP) and suspended particle matter (SPM) were evaluated seasonally along the river, estuary and coastline. Over 83 % of the GC-MS/MS-identified pesticides were quantified in DAP and 91 % in SPM. Pesticides' average annual amounts were ≅316 ng/L and 1.3 μg/g (fungicides), ≅272 ng/L and 2.2 μg/g (herbicides) and ≅1344 ng/L and 6.6 μg/g (insecticides). Invertebrates were the most vulnerable trophic level in the theoretical assessment of pesticide mixture hazards. This hypothesis was strengthened by acute in vivo assays using Artemia salina and Daphnia magna. These data, and the fact that 38 % of pesticides showed concentrations above the maximum established by the European legislation, plus the high concentrations of nitrates, nitrites, ammonia and phosphates, request further depollution actions in this region.

The distribution and human health risk assessment of eight neonicotinoid residues in agricultural soils from four provinces, south China

The widespread use of neonicotinoid (neonic) insecticides in China's agricultural sector has led to high residual concentrations in the agroecosystem. Since soil is the primary source of direct pesticide exposure, soil contamination is a significant concern, particularly in regions with extensive agricultural production. This study aims to determine the spatial distribution of neonics in farmlands from four southern provinces that are home to China's crucial commercial grain bases. By combining eight neonics into imidacloprid-equivalent total neonics (IMI_RPF) using the relative potency factor method, the ecological risks to humans were also assessed. The results showed that imidacloprid had the highest detection rate (96%-100%), followed by thiamethoxam and clothianidin, which ranged from 44% to 64%. Maximum and average IMI_RPF values in soil samples from Zhejiang Province were 277.02 and 46.05 μg kg^-1 (dry weight), respectively. Guangdong (maximum = 191.62 μg kg^-1, mean = 39.70 μg kg^-1) and Jiangxi (maximum = 199.13 μg kg^-1, mean = 28.95 μg kg^-1) had comparable IMI_RPF while Jiangsu had the lowest level of total neonics, with a maximum of 86.07 μg kg^-1 and a mean of 19.49 μg kg^-1. A significant positive correlation between IMI_RPF and total organic carbon in soils was also found. The average daily doses of neonics from soil-borne exposure through food intake, soil ingestion, inhalation, and dermal contact calculated for adults and children in each province were all lower than the reference dose (RfD, 57 μg kg^-1 d^-1) of imidacloprid. However, the potential health risk to human health cannot be disregarded, given their increasing use and pervasiveness in the environment. Our results help to raise concerns about the safety of the agroecological environment under neonic exposure in the major agricultural provinces of southern China.

Evaluating neonicotinoid insecticide uptake by plants used as buffers and cover crops

Runoff and drainage from fields planted with neonicotinoid-coated seeds often contain insecticides that adversely affect aquatic life and other non-target organisms. Management practices such as in-field cover cropping and edge-of-field buffer strips may reduce insecticide mobility, making it important to understand the ability of different plants used in these interventions to absorb neonicotinoids. In this greenhouse study we evaluated uptake of thiamethoxam, a commonly used neonicotinoid, in six plant species - crimson clover, fescue, oxeye sunflower, Maximillian sunflower, common milkweed, and butterfly milkweed - along with a native forb mixture and a native grass plus native forb mixture. All plants were irrigated with water containing 100 or 500 μg/L of thiamethoxam for 60 days, then plant tissues and soils were analyzed for thiamethoxam and its metabolite clothianidin. Crimson clover accumulated up to 50% of the applied thiamethoxam, which was significantly more than other plants and indicates this species may be a hyper-accumulator that can sequester thiamethoxam. In contrast, milkweed plants had relatively low neonicotinoid uptake (<0.5%), meaning that those species may not pose excessive risk to beneficial insects that feed on them. In all plants, accumulated masses of thiamethoxam and clothianidin were greater in above-ground tissues (leaves and stems) than in below-ground roots, with more accrual in leaves than stems. Plants treated with the higher thiamethoxam concentration retained proportionally more of the insecticides. Because thiamethoxam primarily accumulates in above-ground tissues, management strategies that include biomass removal may reduce the input of such insecticides into the environment.

Is a dissipation half-life of 5 years for chlordecone in soils of the French West Indies relevant?

Recently, Comte et al. (2022) re-examined the natural degradation of chlordecone (CLD) in the soils of the French West Indies (FWI) by introducing an additional 'dissipation parameter' into the WISORCH model developed by Cabidoche et al. (2009). Recent data sets of CLD concentrations in FWI soils obtained by Comte et al. enabled them optimizing the model parameters, resulting in significantly shorter estimates of pollution persistence than in the original model. Their conclusions jeopardize the paradigm of a very limited degradation of CLD in FWI soils, which may lead to an entire revision of the management of CLD contamination. However, we believe that their study is questionable on several important aspects. This includes potential biases in the data sets and in the modeling approach. It results in an inconsistency between the estimated dissipation half-life time (DT50) of five years that the authors determined for CLD and the fate of CLD in soil from the application period 1972-1993 until nowadays. Most importantly, a rapid dissipation of CLD in the field as proposed by Comte et al. is not sufficiently supported by data and estimates. Hence, the paradigm of long-term persistence of CLD in FWI soils is still to be considered.