Imidacloprid

Imidacloprid is een systemisch insecticide uit de neonicotinoide groep. De toxiciteit van imidacloprid en zijn metabolieten voor bijen, de verspreiding van imidacloprid in het milieu en de manieren waarop bijen eraan bloot gesteld worden komen aan bod in deze rubriek. Zie ook de imidacloprid-factsheets in de linker menubalk, 4e blok.

Worldwide Integrated Assessment of the Impact of Systemic Pesticides on Biodiversity and Ecosystems

The Worldwide Integrated Assessment of the Impact of Systemic Pesticides on Biodiversity and Ecosystems (WIA) has examined over 800 scientific studies spanning the last five years, including industry sponsored ones. It is the single most comprehensive study of neonics ever undertaken, is peer reviewed, and published as free access so that the findings and the source material can be thoroughly examined by others.

Present scales of use of neonicotinoid pesticides put pollinator services at risk

Scientists urge transition to pollinator-friendly agriculture
Utrecht & Tokyo, 7 June 2013
Honeybee disorders and high colony losses have become global phenomena. An international team of scientist led by Utrecht University synthesized recent findings on the effects of neonicotinoid pesticides on bees. Scientists conclude that owing to their large scale prophylaxic use in agriculture, their high persistence in soil and water, and their uptake by plants and translocation to flowers, neonicotinoids put pollinator services at risk.

Super insecticide imidacloprid has dramatic impact on insect richness in and around water

Press release Utrecht University - May 2, 2013
Insect numbers have been declining in recent years. Research by Utrecht University has found a link between the super insecticide imidacloprid and a decline in abundance of insects and other invertebrates in surface-water. Scientists are ringing international alarm bells. “Stricter standards alone are not enough. This insecticide is so harmful and remains in the environment for so long that an international ban is definitely warranted.”

Late lessen uit vroege waarschuwingen: bijensterfte en systemische insecticiden

In 1994 begonnen Franse bijenhouders melding te maken van alarmerende verschijnselen. Nadat hun honingbijen enkele dagen hadden gefoerageerd op bloeiende zonnebloemen, keerden veel van de bijen niet terug naar de kast. De bijen zaten dicht op elkaar in kleine groepjes op de grond of zweefden gedesoriënteerd voor de kast en vertoonden abnormaal foerageergedrag. In sommige gevallen werden ook dode bijen aangetroffen voor de kast.
Onderzoek wees in de richting van het systemische insecticide Gaucho® van Bayer, dat voor zaadbehandeling wordt gebruikt, met als werkzame stof imidacloprid. In dit hoofdstuk geven we een historisch overzicht van de ontwikkeling van het bewijsmateriaal aangaande risico’s van zonnebloem- en maïszaadbehandeling met Gaucho® voor honingbijen, en analyseren we de acties die zijn ondernomen als reactie op de zich opstapelende aanwijzingen voor deze risico’s.

EFSA identifies risks to bees from neonicotinoids

EFSA scientists have identified a number of risks posed to bees by three neonicotinoid insecticides[1]. The Authority was asked by the European Commission to assess the risks associated with the use of clothianidin, imidacloprid and thiamethoxam as seed treatment or as granules, with particular regard to: their acute and chronic effects on bee colony survival and development; their effects on bee larvae and bee behaviour; and the risks posed by sub-lethal doses[2] of the three substances. In some cases EFSA was unable to finalise the assessments due to shortcomings in the available data.

Grootschalig gebruik neonicotinoïden zet bestuiving op het spel

Wetenschappers dringen aan op transitie naar bijvriendelijke landbouw
Utrecht & Tokyo, 7 juni 2013
Wereldwijd kampen imkers met abnormaal hoge volksterfte en verzwakte bijen. Een internationaal team van wetenschappers geleid door Universiteit Utrecht bracht de recente wetenschappelijke stand van kennis in kaart over de effecten van neonicotinoïde insecticiden op bijen. Grootschalig preventief gebruik in de landbouw, in combinatie met hoge persistentie in bodem en water en opname door planten die het gif doorgeven aan hun stuifmeel en nectar, leiden tot substantiële risico’s. De wetenschappers concluderen dat de bestuiving van bloeiende planten en landbouwgewassen op het spel staat.

Weerwoord op kritiek Vijverberg en Blaauboer op UU PLOS ONE studie imidacloprid & insectenrijkdom

In een ingezonden brief in NRC van 11 mei 2013 geven Henk Vijverberg en voormalig Ctgb college lid Bas Blaauboer vier argumenten waarom ze vraagtekens plaatsen bij de betrouwbaarheid van onze studie in PLOS ONE naar de effecten van imidaclopridvervuiling van oppervlaktewater op de insectenrijkdom in en om het water. In het onderstaande weerleg ik deze argumenten/kritiekpunten een voor een.

Neonicotinoid pesticides are a huge risk – so ban is welcome says EEA

The European Commission has decided to ban three neonicotinoid insecticides. These chemicals can harm honeybees, according to a large body of scientific evidence, so the European Environment Agency (EEA) commends the precautionary decision to ban them.
Read full EEA highlight:
http://www.eea.europa.eu/highlights/neonicotinoid-pesticides-are-a-huge

Brits Lagerhuis wil unaniem een verbod op neonicotinoiden

Vrijdag 5 april 2013 verscheen het rapport van de Britse parlementaire enquette naar de misstanden bij de toelating van neonicotinoide insecticiden. Het parlementaire onderzoek waarin in uren lange zittingen gericht op waarheidsvinding tal van wetenschappers en industriemensen stevig aan de tand gevoeld zijn komt tot heldere conclusies. Er zijn grote redenen tot zorg dat het grootschalig gebruik van neonicotinoiden bijdraagt aan de sterke achteruitgang van wilde bestuivende insecten en bijdraagt aan de toegenomen problemen in de hongingbijenhouderij. Met de toelating is veel mis en de recente veldstudie waarmee Dr. Helen Thompson van Food and Environment Research Agency de eerdere veldstudie van Whitehorn ea (2012) (naar de lange termijn effecten van imidacloprid op het aantal koninginnen per hommelvolk) onderuit dacht te halen, is wetenschappelijk ver beneden de maat. De bevindingen van Whitehorn dat imidacloprid bij normaal toegelaten gebruik zeer schadelijk is voor hommels, blijven overeind.

Belangrijkste aanbeveling, unaniem gedragen door alle partijen in het lagerhuis :
Per 1 januari 2014 moeten imidacloprid, clothianidine en thiamethoxam in Engeland voorlopig worden verboden in voor bijen aantrekkelijke gewassen. Alle toelatingen voor particulier gebruik moeten per direct ingetrokken. De Britse regering moet zich daarnaast inzetten voor een Europees verbod.

Partij voor de Dieren wil onmiddellijk verbod op gevaarlijke bestrijdingsmiddelen

[PERSBERICHT partij voor de dieren]
Neonicotinoïden brengen bijen in gevaar
Partij voor de Dieren wil onmiddellijk verbod op gevaarlijke bestrijdingsmiddelen

Den Haag, 16 januari 2012 - Na een jarenlange discussie over de oorzaken van bijensterfte concludeert ook de Europese Voedsel- en Warenautoriteit dat neonicotinoïden, een zeer giftig landbouwgif, een acuut en ernstig gevaar zijn voor de gezondheid van bijen. De Partij voor de Dieren wil dat deze middelen per direct van de markt worden gehaald.

New Nature study: Combined pesticide exposure severely affects individual- and colony-level traits in bees

Abstract: Reported widespread declines of wild and managed insect pollinators have serious consequences for global ecosystem services and agricultural production1, 2, 3. Bees contribute approximately 80% of insect pollination, so it is important to understand and mitigate the causes of current declines in bee populations 4, 5, 6. Recent studies have implicated the role of pesticides in these declines, as exposure to these chemicals has been associated with changes in bee behaviour7, 8, 9, 10, 11 and reductions in colony queen production12. However, the key link between changes in individual behaviour and the consequent impact at the colony level has not been shown. Social bee colonies depend on the collective performance of many individual workers. Thus, although field-level pesticide concentrations can have subtle or sublethal effects at the individual level8, it is not known whether bee societies can buffer such effects or whether it results in a severe cumulative effect at the colony level. Furthermore, widespread agricultural intensification means that bees are exposed to numerous pesticides when foraging13, 14, 15, yet the possible combinatorial effects of pesticide exposure have rarely been investigated16, 17. Here we show that chronic exposure of bumblebees to two pesticides (neonicotinoid and pyrethroid) at concentrations that could approximate field-level exposure impairs natural foraging behaviour and increases worker mortality leading to significant reductions in brood development and colony success. We found that worker foraging performance, particularly pollen collecting efficiency, was significantly reduced with observed knock-on effects for forager recruitment, worker losses and overall worker productivity. Moreover, we provide evidence that combinatorial exposure to pesticides increases the propensity of colonies to fail.

Movement of Soil-Applied Imidacloprid and Thiamethoxam into Nectar and Pollen of Squash (Cucurbita pepo)

Abstract: There has been recent interest in the threat to bees posed by the use of systemic insecticides. One concern is that systemic insecticides may translocate from the soil into pollen and nectar of plants, where they would be ingested by pollinators. This paper reports on the movement of two such systemic neonicotinoid insecticides, imidacloprid and thiamethoxam, into the pollen and nectar of flowers of squash (Cucurbita pepo cultivars “Multipik,” “Sunray” and “Bush Delicata”) when applied to soil by two methods: (1) sprayed into soil before seeding, or (2) applied through drip irrigation in a single treatment after transplant. All insecticide treatments were within labeled rates for these compounds. Pollen and nectar samples were analyzed using a standard extraction method widely used for pesticides (QuEChERS) and liquid chromatography mass spectrometric analysis. The concentrations found in nectar, 10±3 ppb (mean ± s.d) for imidacloprid and 11±6 ppb for thiamethoxam, are higher than concentrations of neonicotinoid insecticides in nectar of canola and sunflower grown from treated seed, and similar to those found in a recent study of neonicotinoids applied to pumpkins at transplant and through drip irrigation. The concentrations in pollen, 14±8 ppb for imidacloprid and 12±9 ppb for thiamethoxam, are higher than those found for seed treatments in most studies, but at the low end of the range found in the pumpkin study. Our concentrations fall into the range being investigated for sublethal effects on honey bees and bumble bees.

Imidacloprid-Induced Impairment of Mushroom Bodies and Behavior of the Native Stingless Bee Melipona quadrifasciata anthidioides

Abstract: Declines in pollinator colonies represent a worldwide concern. The widespread use of agricultural pesticides is recognized as a potential cause of these declines. Previous studies have examined the effects of neonicotinoid insecticides such as imidacloprid on pollinator colonies, but these investigations have mainly focused on adult honey bees. Native stingless bees (Hymenoptera: Apidae: Meliponinae) are key pollinators in neotropical areas and are threatened with extinction due to deforestation and pesticide use. Few studies have directly investigated the effects of pesticides on these pollinators. Furthermore, the existing impact studies did not address the issue of larval ingestion of contaminated pollen and nectar, which could potentially have dire consequences for the colony. Here, we assessed the effects of imidacloprid ingestion by stingless bee larvae on their survival, development, neuromorphology and adult walking behavior. Increasing doses of imidacloprid were added to the diet provided to individual worker larvae of the stingless bee Melipona quadrifasciata anthidioides throughout their development. Survival rates above 50% were only observed at insecticide doses lower than 0.0056 µg active ingredient (a.i.)/bee. No sublethal effect on body mass or developmental time was observed in the surviving insects, but the pesticide treatment negatively affected the development of mushroom bodies in the brain and impaired the walking behavior of newly emerged adult workers. Therefore, stingless bee larvae are particularly susceptible to imidacloprid, as it caused both high mortality and sublethal effects that impaired brain development and compromised mobility at the young adult stage. These findings demonstrate the lethal effects of imidacloprid on native stingless bees and provide evidence of novel serious sublethal effects that may compromise colony survival. The ecological and economic importance of neotropical stingless bees as pollinators, their susceptibility to insecticides and the vulnerability of their larvae to insecticide exposure emphasize the importance of studying these species.

Effects of imidacloprid, a neonicotinoid pesticide, on reproduction in worker bumble bees (Bombus terrestris)

Abstract: Bumble bees are important pollinators whose populations have declined over recent years, raising widespread concern. One conspicuous threat to bumble bees is their unintended exposure to trace residues of systemic neonicotinoid pesticides, such as imidacloprid, which are ingested when bees forage on the nectar and pollen of treated crops. However, the demographic consequences for bumble bees of exposure to dietary neonicotinoids have yet to be fully established. To determine whether environmentally realistic levels of imidacloprid are capable of making a demographic impact on bumble bees, we exposed queenless microcolonies of worker bumble bees, Bombus terrestris, to a range of dosages of dietary imidacloprid between zero and 125 μg/L and examined the effects on ovary development and fecundity. Microcolonies showed a dose-dependent decline in fecundity, with environmentally realistic dosages in the range of 1 μg/L capable of reducing brood production by one third. In contrast, ovary development was unimpaired by dietary imidacloprid except at the highest dosage. Imidacloprid reduced feeding on both syrup and pollen but, after controlling statistically for dosage, microcolonies that consumed more syrup and pollen produced more brood. We therefore speculate that the detrimental effects of imidacloprid on fecundity emerge principally from nutrient limitation imposed by the failure of individuals to feed. Our findings raise concern about the impact of neonicotinoids on wild bumble bee populations. However, we recognize that to fully evaluate impacts on wild colonies it will be necessary to establish the effect of dietary neonicotinoids on the fecundity of bumble bee queens.

Using video-tracking to assess sublethal effects of pesticides on honey bees (apis mellifera l.)

Abstract - Concern about the role of pesticides in honey bee decline has highlighted the need to examine the effects of sublethal exposure on bee behaviors. The video-tracking system EthoVisionXT (Noldus Information Technologies) was used to measure the effects of sublethal exposure to tau-fluvalinate and imidacloprid on honey bee locomotion, interactions, and time spent near a food source over a 24-h observation period. Bees were either treated topically with 0.3, 1.5, and 3 mg tau-fluvalinate or exposed to 0.05, 0.5, 5.0, 50, and 500 ppb imidacloprid in a sugar agar cube. Tau-fluvalinate caused a significant reduction in distance moved at all dose levels (p<0.05), as did 50 and 500 ppb imidacloprid (p<0.001). Bees exposed to 50 and 500 ppb spent significantly more time near the food source than control bees ( p<0.05). Interaction time decreased as time in the food zone increased for both chemicals. This study documents that video-tracking of bee behavior can enhance current protocols for measuring the effects of pesticides on honey bees at sublethal levels. It may provide a means of identifying problematic compounds for further testing.

The Harvard Study on imidacloprid and CCD - a commentary by Randy Oliver scientificbeekeeping.com

Re this study, at first glance it appears to support the hypothesis that chronic exposure to field realistic doses of imidacloprid during summer and fall can lead to late winter collapse of the treated colonies.

New study from Harvard first to link imidacloprid directly to Colony Collapse Disorder

[Press release Harvard School of Public Health] Imidacloprid, one of the most widely used neonicotinoid pesticides, has been named as the likely culprit in the sharp worldwide decline in honey bee colonies since 2006. Researchers at the Harvard School of Public Health say their new research provides "convincing evidence" of the link between imidacloprid and colony collapse disorder. "It apparently doesn't take much of the pesticide to affect the bees," says Alex Lu, associate professor of environmental exposure biology at Harvard's Department of Environmental Health, "Our experiment included pesticide amounts below what is normally present in the environment."

Aerial powdering of bees inside mobile cages and the extent of neonicotinoid cloud surrounding corn drillers

Abstract
Sudden losses of bees have been observed in spring during maize sowing. The death of bees has been correlated with the use of neonicotinoid-coated seed and the toxic particulates emitted by pneumatic drilling machines. The contamination of foragers in flight over the ploughed fields has been hypothesized. The airborne contamination has been proven, both with bees inside fixed cages around the field and in free flight near the driller. A new trial involving mobile cages has been established and consists of making rapid passes with single bees inside cages fixed to an aluminium bar. The bar was moved by two operators at different distances from the working drilling machine. A single pass was shown as sufficient to kill all the bees exposed to exhaust air on the emission side of the drill, when bees were subsequently held in high relative humidity. The extent of toxic cloud around driller was evaluated at the height of 0.5, 1.8 and 3.5 m and proved to be about 20 m in diameter, with an ellipsoidal shape. The shape may be influenced by working speed of the drill and environmental parameters, and is easily shown by adding talc powder to the seed in the machine hopper. A new driller equipment was evaluated consisting of two tubes inclined towards the soil that direct the exhaust air towards the ground. The survival rate of the bees was not substantially increased using the modified drill and was lower than 50%. Chemical analyses show up to 4000 ng of insecticide in single bees with an average content around 300 ng. Similar quantities were observed at increased distances from the modified or unmodified drillers. This new evaluation of bee mortality in the field is an innovative biological test to verify the hypothetical efficiency (or not) of driller modifications.

Imidacloprid in Melon Guttation Fluid: A Potential Mode of Exposure for Pest and Beneficial Organisms

ABSTRACT ELISA techniques were used to detect imidacloprid in guttation fluid of young cantaloupe plants in Arizona. Imidacloprid was detected at up to 4.1 micro g/ml (ppm) in a coincidental guttation collection 3 d after a top label rate soil application and at 37 micro g/ml one d after a separate top label rate soil application study. These imidacloprid titers exceed reported median oral toxicities for several insect species by factors of 10 or more. Pesticides in guttation fluid are a relatively unexplored route of exposure for both pest and beneficial insects, and could represent an important risk for both of these groups in guttation-prone environments.

Ecologically Appropriate Xenobiotics Induce Cytochrome P450s in Apis mellifera

Abstract
Background: Honey bees are exposed to phytochemicals through the nectar, pollen and propolis consumed to sustain the colony. They may also encounter mycotoxins produced by Aspergillus fungi infesting pollen in beebread. Moreover, bees are exposed to agricultural pesticides, particularly in-hive acaricides used against the parasite Varroa destructor. They cope with these and other xenobiotics primarily through enzymatic detoxificative processes, but the regulation of detoxificative enzymes in honey bees remains largely unexplored.
Methodology/Principal Findings: We used several approaches to ascertain effects of dietary toxins on bee susceptibility to synthetic and natural xenobiotics, including the acaricide tau-fluvalinate, the agricultural pesticide imidacloprid, and the naturally occurring mycotoxin aflatoxin. We administered potential inducers of cytochrome P450 enzymes, the principal biochemical system for Phase 1 detoxification in insects, to investigate how detoxification is regulated. The drug phenobarbital induces P450s in many insects, yet feeding bees with phenobarbital had no effect on the toxicity of taufluvalinate, a pesticide known to be detoxified by bee P450s. Similarly, no P450 induction, as measured by tau-fluvalinate tolerance, occurred in bees fed xanthotoxin, salicylic acid, or indole-3-carbinol, all of which induce P450s in other insects.
Only quercetin, a common pollen and honey constituent, reduced tau-fluvalinate toxicity. In microarray comparisons no change in detoxificative gene expression was detected in phenobarbital-treated bees. However, northern blot analyses of guts of bees fed extracts of honey, pollen and propolis showed elevated expression of three CYP6AS P450 genes. Diet did not influence tau-fluvalinate or imidacloprid toxicity in bioassays; however, aflatoxin toxicity was higher in bees consuming sucrose or high-fructose corn syrup than in bees consuming honey.
Conclusions/Significance: These results suggest that regulation of honey bee P450s is tuned to chemicals occurring naturally in the hive environment and that, in terms of toxicological capacity, a diet of sugar is not equivalent to a diet of honey.

Assessment of the Environmental Exposure of Honeybees to Particulate Matter Containing Neonicotinoid Insecticides Coming from Corn Coated Seeds

ABSTRACT: Since seed coating with neonicotinoid insecticides was introduced in the late 1990s, European beekeepers have reported severe colony losses in the period of corn sowing (spring). As a consequence, seed-coating neonicotinoid insecticides that are used worldwide on corn crops have been blamed for honeybee decline. In view of the currently increasing crop production, and also of corn as a renewable energy source, the correct use of these insecticides within sustainable agriculture is a cause of concern. In this paper, a probable - but so far underestimated - route of environmental exposure of honeybees to and intoxication with neonicotinoid insecticides, namely, the atmospheric emission of particulate matter containing the insecticide by drilling machines, has been quantitatively studied. Using optimized analytical procedures, quantitative measurements of both the emitted particulate and the consequent direct contamination of single bees approaching the drilling machine during the foraging activity have been determined. Experimental results show that the environmental release of particles containing neonicotinoids can produce high exposure levels for bees, with lethal effects compatible with colony losses phenomena observed by beekeepers.

Bee Exposure to Treated Seed Dust During Planting Confirmed

[Viewpoint Beyond Pesticides] Washington, DC--(ENEWSPF)--February 28, 2012. A study by researchers at the University of Padova in Italy and published in the journal Environmental Science and Technology has confirmed the findings of previous research showing that honey bees are exposed to toxic neonicotinoid insecticides during spring seed planting. Neonicotinoids are known to be highly toxic to honey bees and, yet, are used on millions of acres through North America every year. These findings lend even greater urgency to the need to take these chemicals off the market and ensure the continued survival of honey bees and the essential pollination services that they provide for our food system.

Sub-Lethal Effects of Imidacloprid Exposure on Honey Bee Queen Egg-Laying and Activity

Wu, J., V. Krischik and M. Spivak, Department of Entomology, University of Minnesota; St. Paul, MN 55108
Abstract for the 2012 American Bee Research Conference, February 7-8 2012 Greenbelt.

Pesticides such as neonicotinoid insecticides have been implicated as a contributing factor to honey bee losses. The objective of this study is to examine sub-lethal effects of imidacloprid on honey bee queen egg-laying and activity. Observation hives, containing about 1500 bees and a laying queen on newly drawn comb, were given 80 ml of sugar syrup with various imidacloprid treatments (0, 20, 50, 100 ppb) every other day. A total of 16 observation hives, or 4 colonies per treatment, were set-up in July and August of 2011. Queen egg-laying rate and activity were recorded in 15-minute intervals and quantified over 3 weeks. After 3 weeks, colonies were quantified for total adult and brood population, nectar and pollen stores, presence of disease, and weight of newly emerged bees. Preliminary results show that queen laying rates were affected at each imidacloprid treatment dose (20, 50, and 100 ppb). This study will be repeated in the summer of 2012. The findings will improve our understanding of known imidacloprid studies on honey bee colonies and workers. In addition, this study will highlight the need to focus future risk assessment studies on sub-lethal effects of neonicotinyl insecticides on honey bee queen health and behavior.

Pesticide exposure in honey bees results in increased levels of the gut pathogen Nosema

Abstract: Global pollinator declines have been attributed to habitat destruction, pesticide use, and climate change or some combination of these factors, and managed honey bees, Apis mellifera, are part of worldwide pollinator declines. Here we exposed honey bee colonies during three brood generations to sub-lethal doses of a widely used pesticide, imidacloprid, and then subsequently challenged newly emerged bees with the gut parasite, Nosema spp. The pesticide dosages used were below levels demonstrated to cause effects on longevity or foraging in adult honey bees. Nosema infections increased significantly in the bees from pesticide-treated hives when compared to bees from control hives demonstrating an indirect effect of pesticides on pathogen growth in honey bees. We clearly demonstrate an increase in pathogen growth within individual bees reared in colonies exposed to one of the most widely used pesticides worldwide, imidacloprid, at below levels considered harmful to bees. The finding that individual bees with undetectable levels of the target pesticide, after being reared in a sub-lethal pesticide environment within the colony, had higher Nosema is significant. Interactions between pesticides and pathogens could be a major contributor to increased mortality of honey bee colonies, including colony collapse disorder, and other pollinator declines worldwide.

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