Common Neonicotinoid Pesticides Research Articles

The Impact of Neonicotinoid Pesticides on Reproductive Health.

Neonicotinoids are some of the most widely used insecticides in the world because they broadly target chewing and sucking insects. Neonicotinoids are used in commercial agricultural systems, sold for use in home gardens, and found in veterinary pharmaceuticals in the form of flea and tick preventatives for companion animals. They are also used as crop seed treatments and spread throughout crops as they mature. As a result, humans, wildlife, livestock, and pets are routinely exposed to neonicotinoids through consumption of contaminated food and water as well as through use of some veterinary pharmaceuticals. Although several studies indicate that neonicotinoid exposure causes genotoxicity, neurotoxicity, hepatotoxicity, and immunotoxicity in some non-target species, the impact of neonicotinoid pesticides on the male and female reproductive systems in mammals is largely understudied. This review summarizes current insights on the impact of common neonicotinoid pesticides such as acetamiprid, clothianidin, imidacloprid, and thiacloprid on male and female reproductive health in mammals. The review also summarizes the impacts of exposure to mixtures of neonicotinoids on reproductive endpoints. In addition, this review highlights where gaps in research on neonicotinoid pesticides and reproductive health exist so that future studies can be designed to fill current gaps in knowledge.

Deciphering the biodegradation of thiamethoxam by Phanerochaete chrysosporium with natural siderite: Synergistic mechanisms, transcriptomics characterization, and molecular simulation

Fungi play vital roles in the fate of organic pollutants, particularly when interacting with minerals in aquatic and soil environments. Mechanisms by which fungi may mitigate pollutions in fungus-mineral interactions are still unclear. Inspired by biogeochemical cycling, we constructed a range of co-culture systems to investigate synergistic effects of the white-rot fungus Phanerochaete chrysosporium and the iron-bearing mineral siderite on thiamethoxam (THX) transformation, a common neonicotinoid pesticide. Co-culturing with siderite significantly enhanced THX transformation during the initial 10 days with a dose effect, achieving 86 % removal within 25 days. Fungi could affect siderite’s dissolution, transformation, and precipitation through their biological activities. These interactions triggered physiological adaptation and resilience in fungi. Siderite could enhance the activity of fungal ligninolytic enzymes and cytochrome P450, facilitating biotransformation. Genes expression related to growth, energy metabolism, and oxidative stress response upregulated, enhancing fungal resilience to THX. The primary THX degradation pathways included nitro-reduction, C-N cleavage, and de-chlorination. Molecular dynamics simulations provided insights into catalytic mechanisms of enzyme-THX interactions. Together, siderite could act as natural enhancers that endowed fungi to resist physical and chemical stresses in environments, providing insights into contaminants attenuation, fungal biomineralization, and the coevolution of the Earth's lithosphere and biosphere.

An applied potential powered screen-printed electrode for sensitive EC-SERS detection of acetamiprid

Acetamiprid (AAP) is a common neonicotinoid pesticide and their residues have emerged as a widely concerned issue on vegetables and fruits. In this work, a facile electrochemical surface-enhanced Raman spectroscopy (EC-SERS) method with one step of “mixing and detection” was proposed for detection of AAP. Wherein, screen printed electrode (SPE) was modified by dropping silver nanoparticles (AgNPs) onto the SPE surface. Compared to the normal SERS detection, the EC-SERS had a 5-fold enhancement in SERS signal with an applied potential at –0.7 V. Under the optimal applied potential, a wide linear range from 0.1 μM to 1000 μM was achieved with a low limit of detection (LOD, 0.04 μM), about 7-fold lower than that of the normal SERS method (LOD, 0.31 μM). Density functional theory (DFT) calculation revealed that the van der Waals force between AAP molecules and AgNPs was greatly enhanced. Besides, the EC-SERS method was successfully applied for the detection of AAP in Brassica chinensis L., and the results correlated well (R2 =0.9760) with those obtained from liquid chromatography-tandem mass spectrometry (HPLC-MS). The proposed method featured in easy operation, rapid detection and high sensitivity, which can act as a promising tool for monitoring pesticide residues in food samples.

Insight into the toxic effects, bioconcentration and oxidative stress of acetamiprid on Rana nigromaculata tadpoles

Pesticide pollution has been identified as a factor in the amphibian population decrease. Acetamiprid is a common neonicotinoid pesticide that poses a risk to amphibians due to its high water solubility and inability to be digested. However, there is little research on acetamiprid's toxicity in amphibians, particularly on its biochemical toxic effects. In this study, we investigated the acute toxicity, bioenrichment-elimination, biochemical parameters and metabolism of acetamiprid in Rana nigromaculata tadpoles. The results indicated that acetamiprid is harmful to Rana nigromaculata tadpoles, with an LC50 = 18.49 mg L−1 of 96 h for acute toxicity. Acetamiprid showed rapid accumulation and low bioconcentration levels in tadpoles, with bioconcentration factors (BCFs) < 1. In the elimination process, the concentration of acetamiprid decreased rapidly, with the elimination half-life t1/2 values < 1 d. Additionally, oxidative stress was observed in tadpoles, with biochemical parameters such as superoxide dismutase (SOD), catalase (CAT) and malondialdehyde (MDA) being significantly altered. Nontargeted metabolomics revealed significant changes in biomolecules such as lipids, organic acids and nucleotides in tadpoles, and these metabolites influence pathways including serine and threonine metabolism, histidine metabolism, linoleic acid metabolism and sphingolipid metabolism. These results indicate that acetamiprid caused toxic effects on Rana nigromaculata tadpoles. Our study provides a better understanding of the fate and risk of acetamiprid in amphibians, as well as guidelines for its rational use.

BDD electrochemical oxidation of neonicotinoid pesticides in natural surface waters. Operational, kinetic and energetic aspects

Neonicotinoids pesticides were introduced to the market in the 1990s to control various pests. Its accumulation in the environment supposes a severe problem that can affect human health. This study investigates the electrochemical degradation of four common neonicotinoid pesticides; thiamethoxam (TMX), imidacloprid (ICP), acetamiprid (ACP) and thiacloprid (TCP), in different natural surface waters by a boron-doped diamond anode (BDD). The most influencing variable was the current density (j), and to a lesser extent, the supporting electrolyte concentration (Ce). In optimal conditions (j = 34.14 mA cm−2 and Ce = 10.00 mM, using Na2SO4 as electrolyte) pesticide removals for TMX, ICP, ACP and TCP were 97.2, 96.9, 87.8 and 98.2 %, respectively. The obtained results with different support electrolytes (Na2SO4, NaCl, NaNO3 and HK2PO4) suggest that sulphate electrolyte was the optimum for TMX, ICP and ACP. However, for TCP, a total removal was achieved in less than 10 min using NaCl. It was also verified that the initial pH of the solution did not significantly influence the process in the range 3–9. All these results were rationalized in this paper. Finally, to evaluate the matrix influence, some experiments were carried out in different natural surface water matrices (river, reservoir and two different WWTP effluents). The factors influencing the process were the conductivity of the solution and the organic matter content. It was noticeable that the specific energy consumption (SEC) reduced by approximately 15 % for river water and WWTP effluent. High mineralization rates were obtained for all water matrices, with TOC removals ranging between 60 and 80 %.

Development of QuEChERS-DLLME method for determination of neonicotinoid pesticide residues in grains by liquid chromatography-tandem mass spectrometry.

Monitoring neonicotinoid residues in grains is of significant interest for the proper assessment of pesticide exposure to human. The quick, easy, cheap, effective, rugged, and safe extraction method combined with dispersive liquid-liquid micro-extraction (QuEChERS-DLLME) was developed for extracting, purifying, and concentrating seven common neonicotinoid pesticides from the grains (rice, millet, and maize). Water and acetonitrile were used in tandem as extractants in QuEChERS, while water, acetonitrile, and trichloromethane in DLLME acted as the external phase, dispersant, and extractant, respectively. Comprehensive consideration of the single factor test and response surface method to optimize parameters including type and volume of extractants and dispersant. The evaluation showed that the QuEChERS-DLLME method held excellent linearity (R2>0.99). The limits of quantitation ranged from 0.003 to 0.08µgkg-1 for the seven insecticides. The recoveries were in the range of 62-118%, and good reproducibility was obtained with a relative standard deviation below 15%.

Matrix-matched standards in the liquid chromatography–mass spectrometry determination of neonicotinoids in soil and sediment

The use of matrix-matched standards with a solid-liquid extraction and salting out without the addition of further cleanup steps or costly cleanup procedures associated with the quick, easy, cheap, effective, robust, and safe (QuEChERS) method was evaluated to address variations in ionization efficiency in the LC–MS/MS determination of neonicotinoid pesticides in complex environmental samples. Limits of detection (1.4–3.4 ng/g) and limits of quantitation (4.6–11.3 ng/g) for various neonicotinoid analogs were comparable to previously reported QuEChERS extraction methods. Mean recovery of standard neonicotinoid samples spiked with 10 ng/g was found to be 78.0–100.5%, while samples spiked with 100 ng/g were found to be 55.1–99.9%. Recovery of analytes was matrix dependent; the highest recovery was from sediment (86.2–100.5%) followed by laboratory sand (70.9–81.7%) and agricultural soil (55.5–102.6%), respectively. Optimization of this methodology resulted in the reduction of procedure time and cost, and can aid in environmental monitoring efforts of common neonicotinoid pesticides in soils and sediments.

Social Buffering of Pesticides in Bumblebees: Agent-Based Modeling of the Effects of Colony Size and Neonicotinoid Exposure on Behavior Within Nests

Neonicotinoids are a globally prevalent class of pesticides that can negatively impact bees and the pollination services they provide. While there is evidence suggesting that colony size may play an important role in mitigating neonicotinoid exposure in bees, mechanisms underlying these effects are not well understood. Here, a recently developed, agent-based computational model is used to investigate how the effects of sub-lethal neonicotinoid exposure on intranest behavior of bumblebees (Bombus impatiens) are modulated by colony size. Simulations from the model, parameterized using empirical data on bumblebee workers exposed to imidacloprid (a common neonicotinoid pesticide), suggest that colony size has significant effects on behavior neonicotinoid-sensitivity within bumblebee nests. Specifically, differences are reduced between treated and untreated workers in larger colonies for several key aspects of behavior within nests. Our results suggest that changes in both number of workers and nest architecture may contribute to making larger colonies less sensitive to pesticide exposure.

Common pesticide impairs bees’ social behavior

Using robotic cameras, researchers have observed for the first time how a common neonicotinoid pesticide affects bee behavior inside the nest (Science 2018, DOI: 10.1126/science.aat1598). Chronic exposure to neonicotinoids, which are neurotoxic, is known to impair foraging bumblebees’ ability to navigate and recognize flowers, but behavior inside the nest has been a black box. Harvard University postdoc James Crall and colleagues used superglue to tag individual bees with unique paper QR codes, and then dispatched robotic cameras to film the bees inside the nest. The team dosed some bee colonies’ sucrose feed with 6 ppb of imidacloprid, a common neonicotinoid. Wild and agricultural forager bees are likely to accumulate this level of neonicotinoids in their nectar, Crall says. Software analysis of the footage revealed previously hidden behavioral changes. For example, after 12 days, exposed bees spent less time feeding larvae and maintaining the nest, and they interacted less with others

A common neonicotinoid pesticide, thiamethoxam, alters honey bee activity, motor functions, and movement to light

Honey bees provide key ecosystem services. To pollinate and to sustain the colony, workers must walk, climb, and use phototaxis as they move inside and outside the nest. Phototaxis, orientation to light, is linked to sucrose responsiveness and the transition of work from inside to outside the nest, and is also a key component of division of labour. However, the sublethal effects of pesticides on locomotion and movement to light are relatively poorly understood. Thiamethoxam (TMX) is a common neonicotinoid pesticide that bees can consume in nectar and pollen. We used a vertical arena illuminated from the top to test the effects of acute and chronic sublethal exposures to TMX. Acute consumption (1.34 ng/bee) impaired locomotion, caused hyperactivity (velocity: +109%; time moving: +44%) shortly after exposure (30 min), and impaired motor functions (falls: +83%; time top: −43%; time bottom: +93%; abnormal behaviours: +138%; inability to ascend: +280%) over a longer period (60 min). A 2-day chronic exposure (field-relevant daily intakes of 1.42–3.48 ng/bee/day) impaired bee ability to ascend. TMX increased movement to light after acute and chronic exposure. Thus, TMX could reduce colony health by harming worker locomotion and, potentially, alter division of labour if bees move outside or remain outdoors.

Neonicotinoid pesticides can reduce honeybee colony genetic diversity.

Neonicotinoid insecticides can cause a variety of adverse sub-lethal effects in bees. In social species such as the honeybee, Apis mellifera, queens are essential for reproduction and colony functioning. Therefore, any negative effect of these agricultural chemicals on the mating success of queens may have serious consequences for the fitness of the entire colony. Queens were exposed to the common neonicotinoid pesticides thiamethoxam and clothianidin during their developmental stage. After mating, their spermathecae were dissected to count the number of stored spermatozoa. Furthermore, their worker offspring were genotyped with DNA microsatellites to determine the number of matings and the genotypic composition of the colony. Colonies providing the male mating partners were also inferred. Both neonicotinoid and control queens mated with drones originating from the same drone source colonies, and stored similar number of spermatozoa. However, queens reared in colonies exposed to both neonicotinoids experienced fewer matings. This resulted in a reduction of the genetic diversity in their colonies (i.e. higher intracolonial relatedness). As decreased genetic diversity among worker bees is known to negatively affect colony vitality, neonicotinoids may have a cryptic effect on colony health by reducing the mating frequency of queens.

A common neonicotinoid pesticide, thiamethoxam, impairs honey bee flight ability

Pesticides can pose environmental risks, and a common neonicotinoid pesticide, thiamethoxam, decreases homing success in honey bees. Neonicotinoids can alter bee navigation, but we present the first evidence that neonicotinoid exposure alone can impair the physical ability of bees to fly. We tested the effects of acute or chronic exposure to thiamethoxam on the flight ability of foragers in flight mills. Within 1 h of consuming a single sublethal dose (1.34 ng/bee), foragers showed excitation and significantly increased flight duration (+78%) and distance (+72%). Chronic exposure significantly decreased flight duration (−54%), distance (−56%), and average velocity (−7%) after either one or two days of continuous exposure that resulted in bees ingesting field-relevant thiamethoxam doses of 1.96–2.90 ng/bee/day. These results provide the first demonstration that acute or chronic exposure to a neonicotinoid alone can significantly alter bee flight. Such exposure may impair foraging and homing, which are vital to normal colony function and ecosystem services.

Pesticides and pollinators, an automated platform to assess the effects of neonicotinoid exposure and other environmental stressors on bee colonies: a computational, ethological study

BackgroundAnimal pollinators provide vital ecosystem services that sustain biodiversity and support agricultural yields. Declining pollinator populations threaten to affect human health outcomes by decreasing crop yields and human nutrient intake, and there is a well-recognised need to understand how environmental stressors such as pesticides affect bees, the most important animal pollinators. Neonicotinoid pesticides in particular, the most widely used class of insecticide globally, pose a major threat to bees. While there is now strong evidence that neonicotinoids can affect bee behaviour and colony growth, major knowledge gaps remain in understanding how these pesticides affect pollinator health. First, the specific mechanisms by which neonicotinoid exposure affect bee colonies are not well understood, limiting the ability to predict their effects. Second, it is unclear how pesticide exposure interacts with other environmental stressors, which could either amplify or attenuate the effects of neonicotinoids. MethodsWe describe the development of an automated, robotic system aimed at helping to fill these gaps in knowledge. Specifically, this system harnesses advances in computer vision to track the behaviour of hundreds of individual bees across dozens of colonies simultaneously. Specifically, this system uses a computer-controlled, motorised camera array to collect video data from up to a dozen bumblebee colonies in parallel. We then use computer vision-based techniques to automatically measure key aspects of behaviour (eg, activity level, task performance, and social interactions) for individually tagged bees before and after exposure to neonicotinoid pesticides. FindingsUsing a preliminary version of this system, we have found that exposure to field-realistic levels of a common neonicotinoid pesticide (imidacloprid) affects key aspects of social behaviour in bumblebees (Bombus impatiens). These effects include reduced rates of nursing (27% reduction; p<0·001) and interactions with nestmates (–10·6 unique interactions per h; p<0·001), as well as a reduction in activity level within the nest (27% reduction; p<0·001), suggesting a previously unknown mechanism by which pesticide exposure might lead to impaired growth in bee colonies. InterpretationThis automated, parallel system is ideal for studying the effects of multiple environmental stressors, and we are currently extending it to investigate simultaneous exposure to neonicotinoids, thermal stress, and nutritional deficiency on the behaviour and health of bee colonies. This system can provide efficient screening of agrochemicals at low cost, and could provide an important instrument for policymakers and other shareholders to assess the risk of agrochemicals to the health of both bee and human populations. FundingWinslow Foundation, Rockefeller Foundation.

Combined neonicotinoid pesticide and parasite stress alter honeybee queens' physiology and survival.

Honeybee colony survival strongly relies on the queen to overcome worker losses exposed to combined stressors like pesticides and parasites. Queen’s capacity to withstand these stressors is however very little known. The effects of the common neonicotinoid pesticide imidacloprid in a chronic and sublethal exposure together with the wide distributed parasite Nosema ceranae have therefore been investigated on queen’s physiology and survivorship in laboratory and field conditions. Early physiological changes were observed on queens, particularly the increase of enzyme activities (catalase [CAT] and glutathione-S-transferase [GST] in the heads) related to protective responses to xenobiotics and oxidative stress against pesticide and parasite alone or combined. Stressors also alter the activity of two other enzymes (carboxylesterase alpha [CaE α] and carboxylesterase para [CaE p] in the midguts) involved in metabolic and detoxification functions. Furthermore, single and combined effects of pesticide and parasite decrease survivorship of queens introduced into mating hives for three months. Because colony demographic regulation relies on queen’s fertility, the compromise of its physiology and life can seriously menace colony survival under pressure of combined stressors.

Life-Cycle Assessment of Neonicotinoid Pesticides

Neonicotinoid pesticides have been an increasing focus of the environmental community, due to their potential impacts on bee populations and other important insects. The goal of this study was to develop a lifecycle assessment (LCA) approach that could be used to quantify the environmental impacts of two common neonicotinoid pesticides, Imidacloprid and Thiamethoxam. In order to develop the LCA study, an equivalent scenario was created for each pesticide that incorporated data on the production of each pesticide, followed by transportation to a model farm site in Brazil and application with an in-furrow pesticide application system. Data sources for the materials and energy used, combined with resulting emissions to air, water, and soil, were gathered from peer-reviewed literature, government reports, life-cycle inventory databases, and other sources. The SimaPro LCA modeling platform was used to assess the impacts of each life cycle on Human Health and Ecosystem Quality, according to the Impact 2002+ method. Results indicate that important differences exist between the pesticide life cycles, with Thiamethoxam resulting in lower LCA impacts in both impact areas and most mid-point categories under study. Pesticide production impacts varied by over an order of magnitude between the Imidacloprid and Thiamethoxam, while pesticide transport was determined to be a negligible source of environmental impact in both systems. Pesticide application activity using tractors was a larger contributor to Human Health and Ecosystem Quality impacts than the ultimate effect of the pesticide emission to the environment, which should be an area of further study to confirm this finding with the pesticides in question and also to focus impact on the application systems as a potential method of reducing environmental impact, in addition to pesticide toxicity.

Reconciling laboratory and field assessments of neonicotinoid toxicity to honeybees.

European governments have banned the use of three common neonicotinoid pesticides due to insufficiently identified risks to bees. This policy decision is controversial given the absence of clear consistency between toxicity assessments of those substances in the laboratory and in the field. Although laboratory trials report deleterious effects in honeybees at trace levels, field surveys reveal no decrease in the performance of honeybee colonies in the vicinity of treated fields. Here we provide the missing link, showing that individual honeybees near thiamethoxam-treated fields do indeed disappear at a faster rate, but the impact of this is buffered by the colonies' demographic regulation response. Although we could ascertain the exposure pathway of thiamethoxam residues from treated flowers to honeybee dietary nectar, we uncovered an unexpected pervasive co-occurrence of similar concentrations of imidacloprid, another neonicotinoid normally restricted to non-entomophilous crops in the study country. Thus, its origin and transfer pathways through the succession of annual crops need be elucidated to conveniently appraise the risks of combined neonicotinoid exposures. This study reconciles the conflicting laboratory and field toxicity assessments of neonicotinoids on honeybees and further highlights the difficulty in actually detecting non-intentional effects on the field through conventional risk assessment methods.