Global assessment of honeybee exposure to pesticides through guttation consumption: An indicator approach.

Guttation consumption is a potential pathway of pesticide residue exposure in honeybees. However, modeling tools for assessing honeybee exposure to pesticide residues in guttation drops are lacking. In this study, we propose an indicator-based approach for qualitatively or quantitatively analyzing the guttation-based exposure pathway, allowing us to conduct region-specific pesticide residue exposure assessments for honeybees. Exposure scores (the product of guttation production and residue level scores) were established to compare or rank honeybee exposure to pesticide residues via guttation intake across locations using three specified indicators (i.e., air temperature, relative humidity, and precipitation intensity). Warm, dry regions had high residue level scores (indicating high residue levels in guttation), whereas cold, wet regions had high guttation production scores (indicating high possibilities of guttation formation on leaf surfaces); their exposure scores were a combination of these two values. We evaluated and ranked honeybee exposure to imidacloprid residue across regions in Brazil, China, the United States, and selected European Union member states, revealing that pesticide application in many Brazilian federative units may raise honeybee risks due to high exposure scores. We also compared the guttation pathway to other common exposure pathways (nectar and pollen), suggesting that for some moderately lipophilic compounds, the guttation exposure pathway may not be ignored and should be further evaluated.

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.

Micro/trace/toxic elements and insecticide residues level in monofloral bee-collected sunflower pollen- health risk assessment.

The aim of the current research was to determine the content of (potentially) toxic elements and insecticide residues in monofloral sunflower bee-collected pollen. For micro- and trace elements determination Inductively Coupled Plasma Optical Emission (ICP-OES) analytical method was used while insecticide residue content was monitored by applying Liquid Chromatography-Mass Spectrometry (LC-MS/MS) technique. In total, seventeen micro/trace elements were quantified. None of the twenty four examined insecticides were detected above the limit of detection (LOD) which makes studied sunflower bee-collected pollen eco-friendly both to bees and humans. Based on presence of several toxic as well as potentially toxic elements calculations for estimated weekly intakes (EWI), and oral intakes (OI) were made and used for health risk assessment based on the computation of two different health risk quotients (HQ)- acute (HQA) and long-term (HQL). The obtained results proved that all HQ values for adults were negligible or low except in case of HQL value for arsenic (0.32) which can be characterized as medium. However, in case of children much more precaution is needed due to significant HQL risk for arsenic (1.511). The attained data can help to make additional linkage between bee-collected pollen as food ingredients and potential benefits/risks for human health.

Modeling pesticide residues in nectar and pollen in support of pesticide exposure assessment for honeybees: A generic modeling approach.

Pesticide residues in nectar and pollen of plants can damage honeybees; however, few modeling approaches have simulated residue levels in nectar and pollen in support of exposure assessment for honeybees. This study introduced a generic modeling approach based on plant uptake models and simple partitioning rules that specifies soil incorporation and foliar spray application scenarios of pesticides and is flexible for conducting variability analysis for various environmental conditions, pesticide application patterns, chemical individuals, and plant varieties. The results indicated that, in general, systemic or moderate lipophilicity (log KOW of ~2.5) pesticides have relatively high simulated residue levels in nectar and pollen because of the enhanced residue uptake process from soil. For non-systemic or highly lipophilic pesticides, the residue uptake via leaf surface deposition pathway can be enhanced, and more residues will be bioaccumulated in pollen than nectar due to a relatively high lipid content of pollen (as compared to nectar), but the overall residue levels in nectar and pollen are lower than systemic or moderately lipophilic pesticides. The variability analysis showed that environmental conditions, pesticide application patterns, chemical properties, and plant varieties cause considerable variations in simulated residue levels in nectar and pollen, indicating that spatiotemporal, chemical, and plant-related factors must be considered in pesticide exposure assessment for honeybees. Moreover, the comparison between the simulated and measured data showed a high degree of consistency, indicating that the proposed model could be used to conduct a screening-level pesticide exposure assessment for honeybees.

[Residual status, toxicity, and analytical method of banned pesticides in traditional Chinese medicines].

A total of 33 pesticides have been banned from Chinese medicinal materials and decoction pieces(plants) according to Chinese Pharmacopoeia(2020 edition). According to the chemical structures, they are mainly divided into seven categories: organophosphorus compounds, organochlorines, carbamates, amidines, sulfonylureas, phenylpyrazoles, and ethers. These banned pesticides exhibit neurotoxicity, reproductive toxicity, immune system toxicity, teratogenicity, carcinogenesis, and mutagenesis, seriously damaging human and animal health. They affect not only the quality and safety of traditional Chinese medicines and resulting products, but also their competitiveness in the international market. Due to the numerous varieties of traditional Chinese medicines and their complex substrates, it is necessary to establish a universal and highly sensitive method for pesticide residue detection. This review systematically summarized the residual status, toxicity, and analytical methods of banned pesticides in traditional Chinese medicines, and forecasted the prospects of different analytical techniques, so as to provide reference for further safety and risk assessment of banned pesticide residues in traditional Chinese medicines, thus ensuring the safe production of traditional Chinese medicines.

Occurrence and human health risk assessment of mineral elements and pesticides residues in bee pollen.

Bee pollen contains a diversity of bioactive components. Nevertheless, since pollen is retrieved from a variety of plants, including the cultivated ones which are subjected to agrochemical treatments, its contamination is unavoidable. In this context, 45 samples of pollen were analysed with optimized analytical methods for trace and macro elements (ICP-MS), pesticides and metabolites residues (LC & GC-MS/MS) content. According to the results, potassium and iron were the most abundant in terms of concentration and frequency of detection, while the contribution of the most hazardous elements, such as lead, arsenic, cadmium and mercury, to the total concentration of trace elements was lower than 1%. For pesticides, coumaphos was the most frequently detected in the examined samples (22%), followed by propargite, azoxystrobin, dimethoate and cypermethrin. Non-carcinogenic health risk assessment demonstrated in the majority of cases negligible risk for adults and children. On the contrary, carcinogenic risk assessment considering a worst case scenario disclosed nickel and in less extent chromium and arsenic, as risk drivers, exhibiting in several samples carcinogenic risk values for adults above the safety threshold. Yet, regarding that both adults and children unlikely will daily consume such pollen quantities, especially on a long-term basis, an overestimation of risk should be appraised.

Health risk assessment of 42 pesticide residues in Tieguanyin tea from Fujian, China.

The objective of this study was to evaluate the residues of 42 pesticides subject to public concern in Tieguanyin tea produced in Fujian, China. The presence of 42 pesticide residues in 90 Tieguanyin tea samples were determined. A total of 17 pesticides were detected. At least one pesticide residue was detected in 65 samples (72.2%). The detected pesticides imidacloprid, tolfenpyrad, bifenthrin, acetamiprid were found in 55.6%, 33.3%, 18.9% and 16.7% of samples, respectively. Pesticide residues in Tieguanyin tea varied significantly over the seasons and across the production regions. Based on data obtained, the health risks associated with long-term exposure to those pesticides were assessed and risks of detected pesticides were ranked. The hazard quotients (HQs) among the detected pesticides range from 5 × 10-8 for fenpropathrin to 3 × 10-4 for imidacloprid. The results demonstrated that despite a high occurrence of pesticide residues in Tieguanyin tea, residue levels observed could not be considered as a serious public health problem. The risk ranking scheme showed dicofol and thiacloprid were considered to pose a medium-risk. The suggestions for 17 detected pesticides used in Tieguanyin tea plantation were made, including those already banned from use in China (dicofol and methomyl), recommended for diminished use (thiacloprid and chlorpyrifos), and permitted use with considering the pre-harvest interval (13 other pesticides).

Residual status, toxicity, and analytical method of banned pesticides in traditional Chinese medicines / 中国中药杂志

A total of 33 pesticides have been banned from Chinese medicinal materials and decoction pieces(plants) according to Chinese Pharmacopoeia(2020 edition). According to the chemical structures, they are mainly divided into seven categories: organophosphorus compounds, organochlorines, carbamates, amidines, sulfonylureas, phenylpyrazoles, and ethers. These banned pesticides exhibit neurotoxicity, reproductive toxicity, immune system toxicity, teratogenicity, carcinogenesis, and mutagenesis, seriously damaging human and animal health. They affect not only the quality and safety of traditional Chinese medicines and resulting products, but also their competitiveness in the international market. Due to the numerous varieties of traditional Chinese medicines and their complex substrates, it is necessary to establish a universal and highly sensitive method for pesticide residue detection. This review systematically summarized the residual status, toxicity, and analytical methods of banned pesticides in traditional Chinese medicines, and forecasted the prospects of different analytical techniques, so as to provide reference for further safety and risk assessment of banned pesticide residues in traditional Chinese medicines, thus ensuring the safe production of traditional Chinese medicines.

Pesticide residues in the pollen and nectar of oilseed rape (Brassica napus L.) and their potential risks to honey bees.

Research evidence suggests that pesticide residues are one of the leading potential causes of the decline in pollinators, especially during vulnerable periods such as foraging in the early springtime. In China, no research quantifies pesticide residues in the nectar and pollen of honey bee colonies during this period or examines the potential risks and toxicity of pesticides to honey bees. Oilseed rape is one of the first and primary bee-attractive plants in most parts of China. Here, we investigated the pesticide residues in the oilseed rape of the years 2017 and 2018 in China. The hazard quotient (HQ) from pollen and nectar and the BeeREX risk assessment were used to evaluate the potential risks of the pesticide residues to honey bees. We detected 48 pesticides in pollen samples and 34 chemicals in nectar samples. The maximum pollen HQ (PHQ) values (contact or oral) ranged from 0.16 to 706,421, and the maximum nectar HQ (NHQ) values (contact or oral) ranged from 0.07 to 185,135. In particular, carbofuran, cyfluthrin, deltamethrin, and fenpropathrin have relatively high PHQ and NHQ values. Our results indicated that further investigation of nearly half of the tested compounds is needed because their PHQ or NHQ values are more than 50. Especially cyfluthrin and carbofuran need advanced tier assessment due to their maximum RQ (risk quotient) values exceeding the level of concern. These results provide valuable guidance for protecting bees and other pollinators in China.

The use of the Hazard Quotient approach to assess the potential risk to honeybees (Apis mellifera) posed by pesticide residues detected in bee-relevant matrices is not appropriate.

BACKGROUND: Pesticide residue data for pollen and nectar are valuable for characterizing realistic exposure of pollinators, e.g. from agricultural crops, flowering margins. Interpretation of residues relies on comparing exposure with toxicity and the Hazard Quotient (HQ) is widely utilized. However, the HQ (threshold of concern 50) was only validated for foliar sprays, based on application rate as a proxy for exposure, not measured residues in bee-relevant matrices. RESULTS: A review of the literature showed a range of HQ approaches and thresholds of concern used to assess non-foliar applications and residues detected in bee-relevant matrices, mostly pollen. The use of the HQ thresholds to assess risks associated with residue data or non-foliar spray application methods is not validated, does not reflect realistic exposure and the conclusions reached differ substantially from current risk assessment approaches. Re-evaluation of residue data from the first published use of the concentration-based HQ (2013) and a recent paper (2021) reduced the proportion of pesticides where a conclusion of potential risk was reached from 30 to 7% and 28% to 3-6%, respectively. CONCLUSIONS: An understanding of the applicability of the selected risk assessment approach to the available residue data is needed to enable robust conclusions to be drawn on the potential risk to bees. Use of the HQ approach to assess the risk posed by application methods other than foliar sprays or residues in nectar and pollen is likely to result in unreliable conclusions. An alternative approach should be used to assess the significance of measured residues.

Effects of developmental exposure to pesticides in wax and pollen on honey bee (Apis mellifera) queen reproductive phenotypes.

Stressful conditions during development can have sub-lethal consequences on organisms aside from mortality. Using previously reported in-hive residues from commercial colonies, we examined how multi-pesticide exposure can influence honey bee (Apis mellifera) queen health. We reared queens in beeswax cups with or without a pesticide treatment within colonies exposed to treated or untreated pollen supplement. Following rearing, queens were open-mated and then placed into standard hive equipment in an "artificial swarm" to measure subsequent colony growth. Our treated wax had a pesticide Hazard Quotient comparable to the average in beeswax from commercial colonies, and it had no measurable effects on queen phenotype. Conversely, colonies exposed to pesticide-treated pollen had a reduced capacity for viable queen production, and among surviving queens from these colonies we observed lower sperm viability. We found no difference in queen mating number across treatments. Moreover, we measured lower brood viability in colonies later established by queens reared in treated-pollen colonies. Interestingly, royal jelly from colonies exposed to treated pollen contained negligible pesticide residues, suggesting the indirect social consequences of colony-level pesticide exposure on queen quality. These findings highlight how conditions during developmental can impact queens long into adulthood, and that colony-level pesticide exposure may do so indirectly.

Plant protection product residues in plant pollen and nectar: A review of current knowledge.

Exposure to Plant Protection Products, PPPs, (fungicides, herbicides and insecticides) is a significant stressor for bees and other pollinators, and has recently been the focus of intensive debate and research. Specifically, exposure through contaminated pollen and nectar is considered pivotal, as it presents the highest risk of PPP exposure across all bee species. However, the actual risk that multiple PPP residues might pose to non-target species is difficult to assess due to the lack of clear evidence of their actual concentrations. To consolidate the existing knowledge of field-realistic residues detected in pollen and nectar directly collected from plants, we performed a systematic literature review of studies over the past 50 years (1968-2018). We found that pollen was the matrix most frequently evaluated and, of the compounds investigated, the majority were detected in pollen samples. Although the overall most studied category of PPPs were the neonicotinoid insecticides, the compounds with the highest median concentrations of residues in pollen were: the broad spectrum carbamate carbofuran (1400 ng/g), the fungicide and nematicide iprodione (524 ng/g), and the organophosphate insecticide dimethoate (500 ng/g). In nectar, the highest median concentration of PPP residues detected were dimethoate (1595 ng/g), chlorothalonil (76 ng/g), and the insecticide phorate (53.5 ng/g). Strong positive correlation was observed between neonicotinoid residues in pollen and nectar of cultivated plant species. The maximum concentrations of several compounds detected in nectar and pollen were estimated to exceed the LD50s for honey bees, bumble bees and four solitary bee species, by several orders of magnitude. However, there is a paucity of information for the biggest part of the world and there is an urgent need to expand the range of compounds evaluated in PPP studies.

Impact of pesticide polarity and lipid phase dimensions on the bioaccessibility of pesticides in agricultural produce consumed with model fatty foods.

For most people, the pesticide residues found on agriculture products are the main source of pesticide exposure, which may adversely influence consumer health. The potential health hazard of residual pesticides depends on the nature of the foods they are consumed with. Studies with fat-soluble vitamins and nutraceuticals have shown that their bioaccessibility depends on food matrix composition and structure. We used an in vitro method to investigate the influence of the dimensions of the lipid phase in model fatty foods (emulsified or bulk oil) on the bioaccessibility of various pesticides. Three pesticides that differed in their oil-water partition coefficients were selected: bendiocarb (log P = 1.7), parathion (log P = 3.8), and chlorpyrifos (log P = 5.3). These pesticides were mixed with tomato puree to represent pesticide-treated agricultural products. Three model foods with different oil phase dimensions were used to represent different kinds of food product: small emulsions (d32 = 0.14 µm); large emulsions (d32 = 10 µm); and, bulk oil. Our results showed that the oil droplets underwent extensive changes as they passed through the simulated gastrointestinal tract due to changes in environmental conditions, such as pH, ionic strength, bile salts, and enzyme activities. The initial rate and final amount of lipid hydrolysis decreased with increasing lipid phase dimensions. Pesticide bioaccessibility depended on both the hydrophobicity of the pesticide and the dimensions of the co-ingested lipid droplets. The least hydrophobic pesticide (bendiocarb) had a high bioaccessibility (>95%) that did not depend on lipid phase dimensions. The more hydrophobic pesticides (parathion and chlorpyrifos) has a lower bioaccessibility that increased with decreasing lipid phase dimensions. Our results demonstrate the critical role that food structure plays on the potential uptake of pesticides from agricultural products, like fruits and vegetables.

Comet assay genotoxicity evaluation of occupationally exposed tea-garden workers in northern West Bengal, India.

To assess possible genotoxic effects of pesticide exposure in occupationally exposed tea-garden workers, DNA damage in peripheral blood lymphocytes was evaluated with the comet assay. The effects of smoking and alcohol consumption were also examined. The comet tail length, % tail DNA, and Olive tail moment were significantly higher in pesticide-exposed workers compared to non-exposed controls. None of the damage parameters differed when control smokers and control alcohol consumers were compared with controls. However, pesticide-exposed individuals had significantly higher comet tail length, % tail DNA, and Olive tail moment than control smokers and control alcohol consumers, suggesting that the DNA damage may be associated with pesticide exposure.

Analysis of exposure to pesticide residues from Traditional Chinese Medicine.

The safety of Traditional Chinese Medicine (TCM) is of concern worldwide. Herein, Paeoniae Radix Alba, Chaenomelis Fructus and Moutan Cortex, representing three medicinal components, were subjected to toxicological analysis to investigate possible pesticide contamination. Exposure using a point estimate model identified 47 residues that were simultaneously validated by the QuEChERS-UPLC-MS/MS method, which is sufficiently reliable for measuring residue concentrations. Of the 313 samples tested, 94.57% contained pesticide residues, with concentrations ranging from 0.10 to 1199.84 µg kg-1, of which >83.17% contained 4-15 different residues. Carbendazim was the most frequently detected pesticide (>85%), and procymidone, pendimethalin and phoxim were also abundant (median concentration = 15.33-623.12 µg kg-1). Risk assessment based on the hazard quotient/hazard index (HQ/HI) approach revealed that exposure to pesticide residues in all three TCMs (95th percentile) were far below levels that might pose a health risk. However, insecticides contributed to cumulative exposure, especially phoxim, and worryingly, several banned pesticides were detected. The results are of theoretical and practical value for evaluating the safety TCMs, and could improve their quality and safety.

Assessing bioactivity-exposure profiles of fruit and vegetable extracts in the BioMAP profiling system.

The ToxCast program has generated in vitro screening data on over a thousand chemicals to assess potential disruption of important biological processes and assist in hazard identification and chemical testing prioritization. Few results have been reported for complex mixtures. To extend these ToxCast efforts to mixtures, we tested extracts from 30 organically grown fruits and vegetables in concentration-response in the BioMAP® assays. BioMAP systems use human primary cells primed with endogenous pathway activators to identify phenotypic perturbations related to proliferation, inflammation, immunomodulation, and tissue remodeling. Clustering of bioactivity profiles revealed separation of these produce extracts and ToxCast chemicals. Produce extracts elicited 87 assay endpoint responses per item compared to 20 per item for ToxCast chemicals. On a molar basis, the produce extracts were 10 to 50-fold less potent and when constrained to the maximum testing concentration of the ToxCast chemicals, the produce extracts did not show activity in as many assay endpoints. Using intake adjusted measures of dose, the bioactivity potential was higher for produce extracts than for agrichemicals, as expected based on the comparatively small amounts of agrichemical residues present on conventionally grown produce. The evaluation of BioMAP readouts and the dose responses for produce extracts showed qualitative and quantitative differences from results with single chemicals, highlighting challenges in the interpretation of bioactivity data and dose-response from complex mixtures.

Dose-related impacts of imidacloprid oral intoxication on brain and liver of rock pigeon (Columba livia domestica), residues analysis in different organs.

Available data regarding Imidacloprid (IMI) insecticide hazards to birds are still being scare. Our study aimed to investigate toxic impacts of IMI oral gavage by different dose levels on the brain and liver of Rock pigeon (Columba livia domestica). Forty mature male birds were divided equally into four groups. A control group (C) was orally dosed Mazola corn oil and other three groups; the low dose (LD), the medium dose (MD), and the high dose (HD) groups were orally dosed IMI in Mazola corn oil by three dose levels corresponding to 1/15th, 1/10th, 1/5th IMI oral LD50 respectively. IMI exposure induced a significant decrease in serum levels of glutathione (GSH), superoxide dismutase (SOD) enzyme activity. On the other hand; malondialdehyde (MDA) levels were elevated. The levels of serum total protein, albumin, globulin, and A/G ratio showed a non-significant changes in all IMI dosed groups except levels of total protein in the HD IMI dosed group showed a significant decrease compared to the C group. Serum levels of alanine aminotransferase (ALT), lactate dehydrogenase (LDH), uric acid, plasma tumor necrosis factor α (TNFα) and plasma acetylcholinesterase (AChEs) enzyme activities showed a significant dose related increase in all IMI exposed groups compared to the C group; except the levels of ALT, LDH, and uric acid showed a non significant decrease in the LD IMI dosed group only. Residues of IMI were detected in the pectoral muscles, liver, brain, and kidney of all dosed rock pigeon. Moreover; pectoral muscles were the highest tissue for IMI residues detection. This is the first study reports accumulation of IMI in tissues other than crop, liver, and kidney of rock pigeon including brain and muscles. Moreover, the examined brain and liver tissues of all IMI dosed groups showed dosed related alterations in their structural and ultra-structural morphology. It is concluded that IMI oral administration to pigeon induced oxidative stress and detrimental effects in brain and liver of exposed pigeons. Additionally; IMI bio-accumulated in different organs being muscles is the highest tissues for IMI residues, thus monitoring of IMI residues in food is very essential.

Effects of sequential exposure to water accommodated fraction of crude oil and chlorpyrifos on molecular and biochemical biomarkers in rainbow trout.

Fish can be simultaneously or sequentially exposed to various kinds of pollutants, resulting in combined effects. Polycyclic aromatic hydrocarbons induce cytochrome P450 monooxygenase 1A (CYP1A) expression, which catalyzes the conversion of the organophosphorus insecticide chlorpyrifos (CPF) into its most active derivative, CPF-oxon. CPF-oxon inhibits CYP1A and other enzymes, including carboxylesterases (CEs) and acetylcholinesterase (AChE). We studied the effects of an in vivo exposure to crude oil water accommodated fraction (WAF) followed by an ex vivo exposure of liver tissue to CPF on the expression of Cyp1a, AhR and ARNT mRNA, CYP1A protein and on the activity of biomarker enzymes in the rainbow trout (Oncorhynchus mykiss). Juvenile rainbow trout were exposed to WAF (62 µg L-1 TPH) for 48 h. Then, liver was dissected out, sliced and exposed to 20 µg L-1 CPF ex vivo for 1 h. Liver tissue was analyzed for mRNA and protein expression and for CEs, AChE, glutathione S-transferase (GST) and CYP1A (EROD) activity. WAF induced Cyp1a mRNA and CYP1A protein expression by 10-fold and 2.5-8.3-fold, respectively, with no effect of CPF. WAF induced AhR expression significantly (4-fold) in control but not in CPF treated liver tissue. ARNT mRNA expression was significantly lowered (5-fold) by WAF. CPF significantly reduced liver EROD activity, independently of WAF pre-treatment. CEs activity was significantly inhibited in an additive manner following in vivo exposure to WAF (42%) and ex vivo exposure to CPF (19%). CPF exposure inhibited AChE activity (37%) and increased GST activity (42%).

Concentrations of imidacloprid and thiamethoxam in pollen, nectar and leaves from seed-dressed cotton crops and their potential risk to honeybees (Apis mellifera L.).

Neonicotinoid insecticides (NIs) have recently been recognized as co-factors in the decline of honeybee colonies because most neonicotinoids are systemic and can transfer into the pollen and nectar of many pollinated crops. In this study, we collected pollen, nectar and leaves from a cotton crop treated with imidacloprid and thiamethoxam to measure the residue levels of these two NIs at different application doses during the flowering period. Then, the residual data were used to assess the risk posed by the systemic insecticides to honeybees following mandated methods published by the European Food Safety Authority (EFSA), and a highly toxic risk to honeybees was highlighted. Imidacloprid was found in both pollen and nectar samples, whereas thiamethoxam was found in 90% of pollen samples and over 60% of nectar samples. Analysis of the pollen and nectar revealed residual amounts of imidacloprid ranging from 1.61 to 64.58 ng g-1 in the pollen and from not detected (ND) to 1.769 ng g-1 in the nectar. By comparison, the thiamethoxam concentrations in pollen and nectar ranged from ND to 14.521 ng g-1 and from ND to 4.285 ng g-1, respectively. The results of this study provide information on the transfer of two NIs from seed treatment to areas of the plant and provides an understanding of the potential exposure of the bee and other pollinators to systemic insecticides.

Field Residues and Effects of the Insect Growth Regulator Novaluron and Its Major Co-Formulant N-Methyl-2-Pyrrolidone on Honey Bee Reproduction and Development.

Owing to the recent declines in honey bee (Apis mellifera L.) populations, there is a need for field and laboratory studies to investigate threats to pollinator health. This study examines the hypothesis that the organophosphate alternative, Rimon 0.83EC, can have consequences to honey bee health by combining newly acquired field residue data, laboratory bioassays, and colony level feeding studies. Following label rate applications of Rimon 0.83EC to apple trees, average residue concentrations of the active ingredient, novaluron, were found to be 3.38 ppm in tree-collected pollen. Residues of the major co-formulant in Rimon 0.83EC, N-methyl-2-pyrrolidone (NMP), were below the limit of detection in the field, but a growth chamber study described here found that NMP can persist in pollen for up to 7 d with average concentrations of 69.3 ppm. Concurrent larval rearing studies found novaluron and NMP to be toxic to developing honey bees at doses as low as 100 ppb and 100 ppm, respectively. Nucleus colony feeding studies found that chronic exposure to Rimon 0.83EC at doses as low as 200 ppm (18.6 ppm novaluron) can result in interruptions to brood production that can last for up to 2 wk after exposure. Taken together, these data indicate the use of Rimon 0.83EC on blooming flowers is a significant threat to honey bee reproduction, and suggest the need for more strict and clear usage guidelines.