Bijensterfte, oorzaken en gevolgen

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.

Fleas and ticks are a profitable market for the chemical/pesticide industry, but ‘convenient’ spot-on flea and tick treatments have come under fire recently. The active ingredients in these pet products used to be organophosphates (such as chlorpyrifos, dichlorvos, phosmet, naled, tetrachlorvinphos, diazinon, or malathion) and carbamates (such as carbaryl or propoxur), but these chemicals are being phased out and replaced by newer insecticides such as imidacloprid. Modern ‘spot-on’ products may not harm pets or humans with the initial exposure, or even after several exposures. Exposed in this way it takes longer for negative effects to reveal themselves. Small chronic exposures add up. As with small children, pets cannot report when they’re being poisoned at low doses.

Two out of 20 tea products recently tested in New Taipei City contained excessive levels of pesticide residue, according to the results of a food safety check released by the city's Public Health Bureau. The bureau found that the products contained more than twice the tolerable limits of below 3 ppm and 1 ppm for Imidacloprid and Carbofuran, respectively.

The Independent, 7 Jan 2011
Nicotine, found in tobacco, is a deadly substance – and not only for smokers. It has long been known as a powerful natural insecticide, and its presence in the tobacco crop has evolved to deter pests; it is toxic to virtually all of them.
In the great mysterious crash of bee populations, which has been gathering speed around the world for the past decade or so, and which has started to alarm even governments because of the vast worth of bee pollination to the agricultural economy (more than £12bn annually just in Europe), neonicotinoids are increasingly suspect. In the great crash of other insect populations which has similarly been taking place, about which governments do not give a toss but which nonetheless threatens the natural environment with catastrophe (many insectivorous birds are dropping dramatically in numbers), neonicotinoids are similarly in the frame.
Read the full story in The Independent:
www.independent.co.uk/environment/nature/nature_studies/nature-studies-by-michael-mccarthy-have-we-learned-nothing-since-silent-spring-2177935.html

[NGO Viewpoint] AMERICAN BEE EMERGENCY -- ACT NOW!
Bees are dying off and our entire food chain is in peril. Scientists blame toxic pesticides, and four European governments have already banned them, but the deadly poison is still for sale in the USA. If we urgently get the government to join the ban we could save bees from extinction. Sign the petition and forward this appeal

Marie-Pierre Chauzat, Anne-Claire Martel, Nicolas Cougoule, Philippe Porta, Julie Lachaize, Sarah Zeggane, Michel Aubert, Patrice Carpentier And Jean-Paul Faucon, Environ. Toxicol. Chem. 30, pre-published online.

Abstract — The frequency of occurrence and relative concentration of 44 pesticides in apicultural (Apis mellifera) matrices collected from five French locations (24 apiaries) were assessed from 2002 to 2005. The number and nature of the pesticides investigated varied with the matrices examined—living honeybees, pollen loads, honey, and beeswax. Pollen loads and beeswax had the highest frequency of pesticide occurrence among the apiary matrices examined in the present study, whereas honey samples had the lowest. The imidacloprid group and the fipronil group were detected in sufficient amounts in all matrices to allow statistical comparisons. Some seasonal variation was shown when residues were identified in pollen loads.Given the results (highest frequency of presence) and practical aspects (easy to collect; matrix with no turnover, unlike with bees that are naturally renewed), pollen loads were the best matrix for assessing the presence of pesticide residues in the environment in our given conditions.

James E. Cresswell, Ecotoxicology, article in press, pre-published online 16 November 2010

Abstract: Honey bees provide important pollination services to crops and wild plants. The agricultural use of systemic insecticides, such as neonicotinoids, may harm bees through their presence in pollen and nectar, which bees consume. Many studies have tested the effects on honey bees of imidacloprid, a neonicotinoid, but a clear picture of the risk it poses to bees has not previously emerged, because investigations are methodologically varied and inconsistent in outcome. In a meta-analysis of fourteen published studies of the effects of imidacloprid on honey bees under laboratory and semi-field conditions that comprised measurements on 7073 adult individuals and 36 colonies, fitted dose–response relationships estimate that trace dietary imidacloprid at field-realistic levels in nectar will have no lethal effects, but will reduce expected performance in honey bees by between 6 and 20%. Statistical power analysis showed that published field trials that have reported no effects on honey bees from neonicotinoids were incapable of detecting these predicted sublethal effects with conventionally accepted levels of certainty.

These findings raise renewed concern about the impact on honey bees of dietary imidacloprid, but because questions remain over the environmental relevance of predominantly laboratory-based results, I identify targets for research and provide procedural recommendations for future studies.