Bijensterfte, oorzaken en gevolgen

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.

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.

[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."

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.

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.

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.

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.

[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.

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.

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.

Op dinsdag 13 september sprak de Tweede Kamer over gewasbeschermingsmiddelen en bijensterfte. Er werden moties ingediend die vragen om ondermeer:

• [Ouwehand PvdD] de herbeoordeling van neonicotinoïden van het CTGB voor toetsing voor te leggen aan onafhankelijke onderzoekers;
• [Van Gerven SP] onmiddellijk een verbod uit te vaardigen voor het gebruikvan gevaarlijke bestrijdingsmiddelen als neonicotinoïden, in die gebieden waarin de aanvaardbare normen in het oppervlakte- of grondwater worden overschreden;
• [Van Gerven SP] dat een onafhankelijke commissie van onder andere ethici en wetenschapsfilosofen onderzoek doet naar de onafhankelijkheid en objectiviteit bij de beoordeling van toelating van gewasbeschermingsmiddelen en de verwevenheid met het bedrijfsleven van het CTGB;
• [Jacobi PvdA] onder regie van het ministerie van Volksgezondheid nader onderzoek op de vermeende effecten van imidacloprid op het zenuwstelsel van de mens;
• [Koopmans CDA] de toelatingsprocedure voor landbouwgif zo eenvoudig en goedkoop mogelijk te maken

Bij de stemming in de nacht van 15 op 16 september zijn al deze moties - met uitzondering van de motie Koopmans - verworpen.

Thursday, 08 Sep 2011
Report by Sue Kedgley MP in New Zealand to the Local Government and Environment Select Committee

1. An urgent reassessment by the ERMA [now EPA] of Neonicotinoid insecticides, and the use of other pesticides that are highly toxic to bees

The petition calls for an urgent reassessment by the Environment Protection Agency of the use of Neonicotinoid insecticides in New Zealand-and in particular their use as a seed coating on seeds such as grass and maize, as there is mounting evidence that Neonicotinoids may be contributing to unacceptable levels of bee deaths and to the phenomenon of Colony Collapse Disorder overseas.

Den Haag, 1 juni 2011
Geachte Voorzitter,

Per brief heb ik uw Kamer op 28 april jl. laten weten welke besluiten het College voor de toelating van gewasbeschermingsmiddelen en biociden (Ctgb) heeft genomen op basis van de voorlopige resultaten van de herbeoordeling van de effecten van neonicotinoïden op bijensterfte. In dezelfde brief heb ik ook aangegeven dat ik het Ctgb heb verzocht drie insectendodende middelen voor niet-professioneel gebruik voor spuit- en aangiettoepassingen te heroverwegen en deze te verbieden of de toelating ervan op te schorten in afwachting van de definitieve herbeoordeling.

Geachte Voorzitter,

Per brief (Kamerstukken II 2010/11, 32 372, nr. 46) heb ik u op 22 maart jl. laten weten dat het College voor de toelating van gewas­beschermingsmiddelen en biociden (Ctgb) het verzoek van de Kamer inzake de herbeoordeling van neonicotinoiden op de effecten voor bijen uitvoert.

Bijenstichting diende op 22 juli 2010 een bezwaarschrift in tegen het toelatingsbesluit voor het bestrijdingsmiddel Merit Turf.

Merit Turf is een bestrijdingsmiddel op basis van imidacloprid dat door het College voor de Toelating van Gewasbeschermingsmiddelen en Biociden is toegelaten voor de bestrijding van engerlingen en emelten (larven van de meikever en de langpootmug) in golfbanen, sportvelden, graszodenteelt en openbaar gras.

Het bezwaar wordt 20 april 2011 behandeld door de Adviescommissie voor de Bezwaarschriften van Ctgb in een openbare hoorzitting.

An investigation by Buglife – the Invertebrate Conservation Trust has revealed that contrary to statements made by Government scientists from the National Bee Unit on yesterday’s Channel 4 News item - http://www.channel4.com/news/bee-decline-not-caused-by-pesticides -, there is evidence of an increasing link between Neonicotinoid pesticides and bee deaths in Britain.

By Michael McCarthy, Environment Editor - The Independent - Tuesday, 5 April 2011
Bees can detect pesticide residues in the pollen they bring back to the hive and try to isolate it from the rest of the colony, the American government's leading bee scientist revealed in London yesterday.

They "entomb" the contaminated pollen in cells which are sealed over, so they cannot be used for food, said Dr Jeffrey Pettis, head of the Bee Research Laboratory of the US Department of Agriculture.

[NGO Viewpoint] The Japan Endocrine-disruptor Preventive Action programme published a report on the impacts of the very large scale use of neonicotinoid insecticides (Nitenpyram, Thiamethoxam, Thiacloprid, Dinotefuran, Clothianidin, Imidacloprid and Acetamiprid) in Japan on ecosystems, honeybees and human health in Japan.

A MIXTURE of chemicals found in modern pesticides may be killing bee colonies around the world, according to a UN report. Seeds are being coated in systemic insecticides that spread throughout the plant, from the roots to the flowers and into the nectar and pollen. The report says that the highly toxic chemicals in the insecticides, collectively known as neonicotinoids, can cause loss of the sense of direction and memory on which bees rely to find food. The UN Environment Program (Unep) report says that when neonicotinoids are combined with certain fungicides, the toxicity becomes 1000 times stronger.

De voor bijen zeer schadelijke insecticiden uit de neonicotine-groep (ondermeer imidacloprid, thiamethoxam, clothianidine en thiacloprid) zijn in Nederland zeer ruim toegelaten. Een overzicht van de gewassen en teelten waar het wordt gebruikt is hier te vinden:

[From Buzzaboutbees.net Feb 2011]
Varroa mite is one of the biggest threats to honey bee colonies. In the UK, it was first discovered in 1992. Exposure to this pest causes viruses and diseases to be transmitted to honey bees, such as Deformed Wing Virus. But could it be that neonicotinoid pesticides play a role in Varroa too?

The world’s bee populations are under an increasing – and perhaps under-estimated range of threats. These threats comprise a suite of problems including new exotic pathogens, loss of diverse forage, a new generation of insecticides, the stresses we place on our hives through moving them, and introducing chemical controls for existing pathogens like the Varroa bee mite. We cannot eliminate pathogens like Varroa once they are here, but we can do something about another major challenge facing honeybees - the new generation of insecticides called neonicotinoids.

"We zijn bezig de insecten uit te roeien", meent toxicoloog Henk Tennekes. Bijen, hommels, maar ook vlinders, kevers en muggen. Steeds meer insecten leggen het loodje.
Lees het hele artikel in De Gelderlander

Abstract: In this study, cell death detected by DNA fragmentation labeling and phosphatidylserine (PS) localization was investigated in the honey bee (Apis mellifera L.) midgut, salivary glands and ovaries after treating larvae with different pesticides offered via an artificial diet. To do this, honey bee larvae reared in an incubator were exposed to one of nine pesticides: chlorpyrifos, imidacloprid, amitraz, fluvalinate, coumaphos, myclobutanil, chlorothalonil, glyphosate and simazine. Following this, larvae were fixed and prepared for immunohistologically detected cellular death using two TUNEL techniques for DNA fragmentation labeling and Annexin V to detect the localization of exposed PS specific in situ binding to apoptotic cells.
Untreated larvae experienced 10% midgut apoptotic cell death under controlled conditions. All applied pesticides triggered an increase in apoptosis in treated compared to untreated larvae. The level of cell death in the midgut of simazine-treated larvae was highest at 77% mortality and statistically similar to the level of cell death for chlorpyrifos (65%), imidacloprid (61%), myclobutanil (69%), and glyphosate (69%) treated larvae. Larvae exposed to fluvalinate had the lowest midgut columnar apoptotic cell death (30%) of any pesticide-treated larvae. Indications of elevated apoptotic cell death in salivary glands and ovaries after pesticide application were detected. Annexin V localization, indicative of apoptotic cell deletion, had an extensive distribution in the midgut, salivary glands and ovaries of pesticide-treated larvae.
The data suggest that the tested pesticides induced apoptosis in tissues of honey bee larvae at the tested concentrations. Cell death localization as a tool for a monitoring the subclinical and sub-lethal effects of external influences on honey bee larval tissues is discussed.