Systemic insecticides, their degradation products and metabolites in the environment. Quantification methodologies in environmental samples relevant for toxicological and ecotoxicological studies

Systemic insecticides are widely used for pests control and their success is due to their ability of protect the whole plant from roots to the upper leaf. In particular, seeds coating technique is very popular and it is applied to many crops (e.g. corn). However, the use of high amount of Active Ingridient (AI) for seeds coating is causing concern about negative effects to non-target animals. Pollinators insects are exposed to contaminated pollen and nectar, but also herbivore insects are exposed through contaminated leaf. In addition, these insecticides can leach from fields and contaminate wild plants or waterbodies. Therefore, also aquatic species are exposed to insecticides pollution and vertebrates like birds and small mammals could be exposed through coated seeds, seedling and insects. The aim of this study was to develop an UHPLC-HRMS method for the identification of insecticides and their degradation production in corn guttation drops. Particular attention was posed to metabolites, because few information are available in the literature about their presence in relevant matrix for eco-toxicological studies. In addition, some metabolites may have greater toxicity if compared with their parent compounds. In particular, neonicotinoids imine metabolites are characterised by an inversion of selectivity between insects and mammals. Therefore, they can be more toxic for mammals if compared to the neonicotinoids AI. Several metabolites were identify in corn guttation and an extraction procedure based on QuEChERS strategy coupled with a target UHPLC-MS2 method was developed and validated for the quantification of these compounds in corn leaf. High concentration of neonicotinoids thiamethoxam and thiacloprid were observed in corn seedling. In addition, high concentration of the thiamethoxam metabolite clothianidn was observed. Concerning the carbamate methiocarb, the AI was observed only at low concentration, but its metabolites were present at ug/g level. Particularly interesting was the presence of methiocarb sulfoxide, because this metabolite is more toxic of the parent compounds for some species. In conclusion, guttation analysis with UHPLC-HRMS is a powerful technique in order to assess the presence of insecticides metabolites in plants treated with systemic AI. However, UHPLC-MS2 still provide better performance for quantitative analysis, in particular for complex matrices as corn leaf. Therefore, HRMS and MS2 are complementary technique useful to provide levels of contamination and exposure

A new method to assess the acute toxicity toward honeybees of the abrasion particles generated from seeds coated with insecticides

Background:Large amounts of insecticide-containing dusts produced from abrasion of the seed dressing can be released into the atmosphere during sowing operations. Neonicotinoid pesticides, introduced in the 1990s for several crops, are the leading products for seed-coating treatments in many countries. Neonicotinoid containing dusts can be effectively intercepted by bees in flight over the sowing field, inducing lethal acute effects, so that restrictions in the use of the main neonicotinoids have been adopted in the European Union. This led to the consequent introduc-tion of replacement insecticides for seed-coating, i.e. methiocarb and thiacloprid, despite the lack of information on both the toxicity and the exposure scenarios for honeybees. Results:In this study, a laboratory apparatus was developed in order to quantify the toxicity of the dusts produced from the abrasion of the seed coating. This quantification is based on (i) an airstream transporting coating particles into an exposure chamber; (ii) exposure of bees to reproducible and measurable concentrations of insecticide, and (iii) direct measurement of the exposure dose on single bees. The method allowed us to perform in vivo experiments of honeybee exposure to provide toxicity data in more realistic exposure conditions. In fact, the formulation rather than the active principle alone can be tested, and the exposure is through dusts rather than a solution so that specific absorption behavior can be studied in representative environmental conditions. The method was used to quantify the acute toxicity (LD50) of dusts obtained from the abrasion of corn seeds coated with clothianidin, thiacloprid and methiocarb. Conclusions:Our results show that, surprisingly, the replacement insecticide methiocarb has a toxicity (LD50= 421\u2013693 ng/bee) in the same order of magnitude as clothianidin (LD50=113\u2013451 ng/bee) through this specific exposure route, while thiacloprid (LD50= 16.9\ub7103 ng/bee) has a significantly lower acute toxicity. Moreover, dusts containing methiocarb and clothianidin show a significant increase in toxicity when, after exposure, bees are kept under high humidity conditions. This suggests that the method here presented can be used to obtain complementary toxicity data in the risk assessment procedure for the authorization of new seed-coating insecticides or new formulations

An update of the Worldwide Integrated Assessment (WIA) on systemic insecticides. Part 1: new molecules, metabolism, fate, and transport

With the exponential number of published data on neonicotinoids and fipronil during the last decade, an updated review of literature has been conducted in three parts. The present part focuses on gaps of knowledge that have been addressed after publication of the Worldwide Integrated Assessment (WIA) on systemic insecticides in 2015. More specifically, new data on the mode of action and metabolism of neonicotinoids and fipronil, and their toxicity to invertebrates and vertebrates, were obtained. We included the newly detected synergistic effects and/or interactions of these systemic insecticides with other insecticides, fungicides, herbicides, adjuvants, honeybee viruses, and parasites of honeybees. New studies have also investigated the contamination of all environmental compartments (air and dust, soil, water, sediments, and plants) as well as bees and apicultural products, food and beverages, and the exposure of invertebrates and vertebrates to such contaminants. Finally, we review new publications on remediation of neonicotinoids and fipronil, especially in water systems. Conclusions of the previous WIA in 2015 are reinforced; neonicotinoids and fipronil represent a major threat worldwide for biodiversity, ecosystems, and all the services the latter provide

Methiocarb metabolites are systemically distributed throughout corn plants grown from coated seeds

Funder: Università degli Studi di PadovaAbstract: Systemic insecticides such as neonicotinoids are widely used in seed coating practices for pest control in many crops, e.g., corn. Their success is due to their ability to protect the whole plant, from the roots to the upper leaves, but their use at high amounts is causing possible adverse effects on non-target animals exposed to contaminated pollen, nectar, leaves, and dust emitted during sowing. In 2018, the European Union banned some neonicotinoids and fipronil as seed coating insecticides in open fields. Consequently, the methylcarbamate methiocarb and less-toxic neonicotinoids, e.g., thiacloprid, have been authorized and largely used as alternative pesticides for corn seed coating. Here, an analytical protocol based on QuEChERS extraction/purification procedure and analysis by liquid chromatography-mass spectrometry has been optimized for the identification and the quantification of methiocarb, thiamethoxam, thiacloprid, and their metabolites in guttation drops, the xylem fluid excreted at leaf margins, and in leaves of corn plants grown from coated seeds. Although methiocarb is a non-systemic pesticide, we unexpectedly found high concentrations of its metabolites in both guttations and leaves, whereas methiocarb itself was below detection limits in most of the samples. The methiocarb main metabolite, methiocarb sulfoxide, was found at a mean concentration of 0.61 ± 1.12 µg mL−1 in guttation drops and 4.4 ± 2.1 µg g−1 in leaves. Conversely, parent compounds of neonicotinoids (thiamethoxam, thiacloprid) are systemically distributed in corn seedlings. This result raises safety concerns given that methiocarb sulfoxide is more toxic than the parent compound for some non-target species

Systemic insecticides, their degradation products and metabolites in the environment. Quantification methodologies in environmental samples relevant for toxicological and ecotoxicological studies

Systemic insecticides are widely used for pests control and their success is due to their ability of protect the whole plant from roots to the upper leaf. In particular, seeds coating technique is very popular and it is applied to many crops (e.g. corn). However, the use of high amount of Active Ingridient (AI) for seeds coating is causing concern about negative effects to non-target animals. Pollinators insects are exposed to contaminated pollen and nectar, but also herbivore insects are exposed through contaminated leaf. In addition, these insecticides can leach from fields and contaminate wild plants or waterbodies. Therefore, also aquatic species are exposed to insecticides pollution and vertebrates like birds and small mammals could be exposed through coated seeds, seedling and insects. The aim of this study was to develop an UHPLC-HRMS method for the identification of insecticides and their degradation production in corn guttation drops. Particular attention was posed to metabolites, because few information are available in the literature about their presence in relevant matrix for eco-toxicological studies. In addition, some metabolites may have greater toxicity if compared with their parent compounds. In particular, neonicotinoids imine metabolites are characterised by an inversion of selectivity between insects and mammals. Therefore, they can be more toxic for mammals if compared to the neonicotinoids AI. Several metabolites were identify in corn guttation and an extraction procedure based on QuEChERS strategy coupled with a target UHPLC-MS2 method was developed and validated for the quantification of these compounds in corn leaf. High concentration of neonicotinoids thiamethoxam and thiacloprid were observed in corn seedling. In addition, high concentration of the thiamethoxam metabolite clothianidn was observed. Concerning the carbamate methiocarb, the AI was observed only at low concentration, but its metabolites were present at ug/g level. Particularly interesting was the presence of methiocarb sulfoxide, because this metabolite is more toxic of the parent compounds for some species. In conclusion, guttation analysis with UHPLC-HRMS is a powerful technique in order to assess the presence of insecticides metabolites in plants treated with systemic AI. However, UHPLC-MS2 still provide better performance for quantitative analysis, in particular for complex matrices as corn leaf. Therefore, HRMS and MS2 are complementary technique useful to provide levels of contamination and exposure.Systemic insecticides are widely used for pests control and their success is due to their ability of protect the whole plant from roots to the upper leaf. In particular, seeds coating technique is very popular and it is applied to many crops (e.g. corn). However, the use of high amount of Active Ingridient (AI) for seeds coating is causing concern about negative effects to non-target animals. Pollinators insects are exposed to contaminated pollen and nectar, but also herbivore insects are exposed through contaminated leaf. In addition, these insecticides can leach from fields and contaminate wild plants or waterbodies. Therefore, also aquatic species are exposed to insecticides pollution and vertebrates like birds and small mammals could be exposed through coated seeds, seedling and insects. The aim of this study was to develop an UHPLC-HRMS method for the identification of insecticides and their degradation production in corn guttation drops. Particular attention was posed to metabolites, because few information are available in the literature about their presence in relevant matrix for eco-toxicological studies. In addition, some metabolites may have greater toxicity if compared with their parent compounds. In particular, neonicotinoids imine metabolites are characterised by an inversion of selectivity between insects and mammals. Therefore, they can be more toxic for mammals if compared to the neonicotinoids AI. Several metabolites were identify in corn guttation and an extraction procedure based on QuEChERS strategy coupled with a target UHPLC-MS2 method was developed and validated for the quantification of these compounds in corn leaf. High concentration of neonicotinoids thiamethoxam and thiacloprid were observed in corn seedling. In addition, high concentration of the thiamethoxam metabolite clothianidn was observed. Concerning the carbamate methiocarb, the AI was observed only at low concentration, but its metabolites were present at ug/g level. Particularly interesting was the presence of methiocarb sulfoxide, because this metabolite is more toxic of the parent compounds for some species. In conclusion, guttation analysis with UHPLC-HRMS is a powerful technique in order to assess the presence of insecticides metabolites in plants treated with systemic AI. However, UHPLC-MS2 still provide better performance for quantitative analysis, in particular for complex matrices as corn leaf. Therefore, HRMS and MS2 are complementary technique useful to provide levels of contamination and exposure

Produzione di particolato da sementi conciate con insetticidi neonicotinoidi e valutazione della tossicità in Apis mellifera L.

Neonicotinoid pesticides were introduced in the 90s as product for crop treatment. They have been highly successful and are still widely used for many different crops. In 2008, the use of some of these products have been banned in Italy, to protect non-target insects (bees, in particular) from the toxic effects of these pesticides. This action was necessary because in Italy, and worldwide as well, beekeepers have reported severe colony loss in the period of corn sowing. In December 2013 an European Regulation banned for two years the use of these pesticides in the whole territory of the European Union. In this period will be necessary to collect further data to understand better how the decline of honeybees is related to the use of neonicotinoid pesticides. Therefore is very important to continue the study on the active ingredients subject to the suspension and to extend it to new products that have replaced them. There are many way of use the neonicotinoids: spray, granular for soil treatment and seed coating. Their main use is for the seed coating of corn, a crop widespread throughout the European territory. Other seeds treated with neonicotinoids are rapeseed, sunflower, soybean and sugar beet. The drilling machines used for the sowing, release in the atmosphere large amount of particulate matter, originated from the abrasion of seeds coating. These particles contain the pesticide that causes the contamination of vegetation near to farmland. Furthermore, it causes the acute toxication of flying bees approaching the drilling machines. Some previous experiments have already determinated the amount of insecticide collected by the bees in flight. The doses of pesticide are very high and could cause death of the insects. In the literature there are many studies on the acute toxicity of these pesticides. However, only few works consider the real exposure conditions that take place in the field. Moreover, so far, no study has yet quantified the acute toxicity toward bees of the particulate matter emitted by the drilling machines. In order to investigate this toxic effect, we have optimized a laboratory device for the production of particulate matter which reproduce that emitted by the drilling machine. The aim was the production of an air stream containing a precise and stable concentration of neonicotinoid, for the controlled exposure of bees and the consequent in vivo experimentation. After the standardization of this system, it has been used to quantify the toxicity of two different insecticides used in the corn seed coating. By this device it will be possible to compare the effects of different pesticides used for seed coating and to study the parameters that influence the toxicity of these powders (for example: different conditions of atmospheric humidity or temperature)

A 1-uA Front End for Pacemaker Atrial Sensing Channels with Early Sensing Capability

A low-power front end for a pacemaker atrial sensing channel based on level detection is presented. The very tight system specifications in terms of power consumption and output noise, the need to operate with a supply voltage decreasing from 2.8 to 2 V during the battery lifetime, and additional functionalities with respect to standard front ends, like gain programmability and early sensing, make the design of this system a challenge. The front end includes a preamplifier and a third-order switched capacitor filter, and it is fabricated in a 0.8 \u3bcm CMOS technology. It features a 1 \u3bcA current consumption at a supply voltage of 2.7 V, and an input referred total noise of 6.9 \u3bcVrms

A 1uA Front-End for Pacemaker Atrial Sensing Channels

A low-power front-end for a pacemaker atrial sensing channel based on peak detection is presented. The very tight system specifications in terms of power consumption and output noise, the need to operate with a supply voltage decreasing from 2.8 V to 2 V during the battery lifetime, and additional functionalities with respect to standard front-ends, like gain programmability and early sensing, make the design of this system a challenge. The front-end includes a preamplifier and a 3rd SC filter, and it is fabricated in a 0.8 \ub5m CMOS technology. It features a 1 \ub5A current consumption from a single nominal 2.8 supply (which, however, can decrease down to 2V), 5.1 mVrms total output noise and a maximum voltage gain of 740

Effect of repeated intakes of a neonicotinoid insecticide on the foraging behaviours of Apis mellifera in field trials.

Funder: Università degli Studi di PadovaEvaluating the effects of neonicotinoids on forager bees in conditions as near as possible to those in nature presents a considerable challenge. Tackling this challenge is, however, necessary to establish their negative side effects on these pollinators. For instance, it is still under debate the mechanism by which bees seem to recognize low-level contaminations of neonicotinoid insecticides in nectar and pollen of the flowers they visit and limit collection to protect themselves and their hive from a possible intoxication. In this study, we propose an experimental system that involves the use of foragers in free flight foraging repeatedly on artificial feeders containing a sucrose solution contaminated with clothianidin, as well as foragers feeding at adjacent control feeders, allowing us to observe changes in their foraging activity. The progressive disappearance of foragers from the contaminated feeders became increasingly clear and rapid with the increase in clothianidin concentration. The lowest concentration at which we observed an effect was around 10 µg/L, which corresponds to the maximum residual concentration (10 ng/g) observed in pollen and nectar of flowers close to open fields sown with seeds coated with insecticides. At the highest concentrations tested (80 µg/L), there was an almost total abandonment of the feeders. The estimated quantity of contaminated sucrose solution collected by foragers showed an almost linear relationship inversely proportional to clothianidin concentration, whilst the estimated quantity of insecticide collected by a forager increased and then stabilised at the highest concentrations tested of 40 and 80 µg/L. Irregular mortality was not observed in front of the hives, furthermore, foragers did not show evident memory of the position of the treated units in the trials on the 2 consecutive days. The decrease in foraging activity in the presence of a few µg/L of insecticide in the sucrose solution appears to limit the introduction of elevated amounts of toxic substances into the hives, which would have serious consequences for the young bees and the brood. At the same time, in the absence of an alternative energy source, even reduced feeding of the hive can compromise colony health

Methiocarb metabolites are systemically distributed throughout corn plants grown from coated seeds

Funder: Università degli Studi di PadovaAbstract: Systemic insecticides such as neonicotinoids are widely used in seed coating practices for pest control in many crops, e.g., corn. Their success is due to their ability to protect the whole plant, from the roots to the upper leaves, but their use at high amounts is causing possible adverse effects on non-target animals exposed to contaminated pollen, nectar, leaves, and dust emitted during sowing. In 2018, the European Union banned some neonicotinoids and fipronil as seed coating insecticides in open fields. Consequently, the methylcarbamate methiocarb and less-toxic neonicotinoids, e.g., thiacloprid, have been authorized and largely used as alternative pesticides for corn seed coating. Here, an analytical protocol based on QuEChERS extraction/purification procedure and analysis by liquid chromatography-mass spectrometry has been optimized for the identification and the quantification of methiocarb, thiamethoxam, thiacloprid, and their metabolites in guttation drops, the xylem fluid excreted at leaf margins, and in leaves of corn plants grown from coated seeds. Although methiocarb is a non-systemic pesticide, we unexpectedly found high concentrations of its metabolites in both guttations and leaves, whereas methiocarb itself was below detection limits in most of the samples. The methiocarb main metabolite, methiocarb sulfoxide, was found at a mean concentration of 0.61 ± 1.12 µg mL−1 in guttation drops and 4.4 ± 2.1 µg g−1 in leaves. Conversely, parent compounds of neonicotinoids (thiamethoxam, thiacloprid) are systemically distributed in corn seedlings. This result raises safety concerns given that methiocarb sulfoxide is more toxic than the parent compound for some non-target species