Bijensterfte, oorzaken en gevolgen

Abstract
Since 2006 the rate of honey bee colony failure has increased significantly. As an aid to testing hypotheses for the causes of colony failure we have developed a compartment model of honey bee colony population dynamics to explore the impact of different death rates of forager bees on colony growth and development. The model predicts a critical threshold forager death rate beneath which colonies regulate a stable population size. If death rates are sustained higher than this threshold rapid population decline is predicted and colony failure is inevitable. The model also predicts that high forager death rates draw hive bees into the foraging population at much younger ages than normal, which acts to accelerate colony failure. The model suggests that colony failure can be understood in terms of observed principles of honey bee population dynamics, and provides a theoretical framework for experimental investigation of the problem.

International Bee Research Association Press Release 1 February 2012
Since 2006 there has been concern worldwide about losses of honey bee colonies, especially the phenomenon of “Colony Collapse Disorder” in the USA. Information about the extent of these losses has,to date, been patchy, unsystematic and difficult to compare year on year and from country to country. Today, for the first time, the results of systematic surveys in Europe, north America, China, Israel and Turkey are published together in the Journal of Apicultural Research.

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.

Abstract
Populations of honey bees and other pollinators have declined worldwide in recent years. A variety of stressors have been implicated as potential causes, including agricultural pesticides. Neonicotinoid insecticides, which are widely used and highly toxic to honey bees, have been found in previous analyses of honey bee pollen and comb material. However, the routes of exposure have remained largely undefined. We used LC/MS-MS to analyze samples of honey bees, pollen stored in the hive and several potential exposure routes associated with plantings of neonicotinoid treated maize. Our results demonstrate that bees are exposed to these compounds and several other agricultural pesticides in several ways throughout the foraging period. During spring, extremely high levels of clothianidin and thiamethoxam were found in planter exhaust material produced during the planting of treated maize seed. We also found neonicotinoids in the soil of each field we sampled, including unplanted fields. Plants visited by foraging bees (dandelions) growing near these fields were found to contain neonicotinoids as well. This indicates deposition of neonicotinoids on the flowers, uptake by the root system, or both. Dead bees collected near hive entrances during the spring sampling period were found to contain clothianidin as well, although whether exposure was oral (consuming pollen) or by contact (soil/planter dust) is unclear. We also detected the insecticide clothianidin in pollen collected by bees and stored in the hive. When maize plants in our field reached anthesis, maize pollen from treated seed was found to contain clothianidin and other pesticides; and honey bees in our study readily collected maize pollen. These findings clarify some of the mechanisms by which honey bees may be exposed to agricultural pesticides throughout the growing season. These results have implications for a wide range of large-scale annual cropping systems that utilize neonicotinoid seed treatments.

The traditional approach to toxicity testing is to consider dose (concentration)-effect relationships at arbitrarily fixed exposure durations which are supposed to reflect ‘acute’ or ‘chronic’ time scales. This approach measures the proportion of all exposed individuals responding by the end of different exposure times. Toxicological databases established in this way are collections of endpoint values obtained at fixed times of exposure. As such these values cannot be linked to make predictions for the wide range of exposures encountered by humans or in the environment. Thus, current toxicological risk assessment can be compromised by this approach to toxicity testing, as will be demonstrated in this paper, leading to serious underestimates of actual risk. This includes neonicotinoid insecticides and certain metallic compounds, which may require entirely new approaches.

On 15 November 2011 the EU parliament voted for a resolution on honeybee health. Rising bee mortality could have a serious impact on Europe's food production and environmental stability, as most plants are pollinated by bees, warned MEPs on Tuesday. Parliament's resolution calls on the EU to step up investment in research on new medicines and coordinate its efforts to protect what is fast becoming an endangered species.

Current Biology, Volume 21, Issue 17, 13 September, 2011
The spread of herbicide-resistant weeds, progress in genomics, climate change and the continuing worries about pollinator decline are forcing companies to rethink their approach to crop protection. Michael Gross reports.

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.

ABSTRACT: The honeybee, Apis mellifera, is undergoing a worldwide decline whose origin is still in debate. Studies performed for twenty years suggest that this decline may involve both infectious diseases and exposure to pesticides. Joint action of pathogens and chemicals are known to threaten several organisms but the combined effects of these stressors were poorly investigated in honeybees. Our study was designed to explore the effect of Nosema ceranae infection on honeybee sensitivity to sublethal doses of the insecticides fipronil and thiacloprid.

ABSTRACT: The contribution of nutrients from animal pollinated world crops has not previously been evaluated as a biophysical measure for the value of pollination services. This study evaluates the nutritional composition of animal-pollinated world crops. We calculated pollinator dependent and independent proportions of different nutrients of world crops, employing FAO data for crop production, USDA data for nutritional composition, and pollinator dependency data according to Klein et al. (2007). Crop plants that depend fully or partially on animal pollinators contain more than 90% of vitamin C, the whole quantity of Lycopene and almost the full quantity of the antioxidants β-cryptoxanthin and β-tocopherol, the majority of the lipid, vitamin A and related carotenoids, calcium and fluoride, and a large portion of folic acid. Ongoing pollinator decline may thus exacerbate current difficulties of providing a nutritionally adequate diet for the global human population.

A 10-month study of healthy honey bees by University of California, San Francisco (UCSF) scientists has identified four new viruses that infect bees, while revealing that each of the viruses or bacteria previously linked to colony collapse is present in healthy hives as well.

Ljubljana, 3 June (STA) - Slovenian agriculture authorities have confirmed that a pesticide suspected of causing massive bee deaths in NE Slovenia in late April was indeed a leading cause of the deaths and announced new measures, including lawsuits against producers of the pesticide.

Researchers from the University of Reading have shown that wild bees are the unsung heroes for our food security and not honeybees as previously thought.

[NGO viewpoint, Wednesday, 25 May 2011 Sue Kedgley]
Unless we take decisive action to protect our bees, we could be faced with massive bee deaths, a horticultural industry in crisis, food shortages and escalating food prices.

The honey bee is indispensable to our horticulture, our ecology and our economy. Yet the honey bee is in crisis all around the world, with bee populations being decimated by a phenomenon known as Colony Collapse Disorder, where entire colonies of bees disappear.

Treated Corn Seed and Pesticide Banned as Bee Deaths Continue
Ljubljana, 28 April 2011 (STA) - The government of Slovenia issued a temporary ban Thursday on seeds treated with neonicotinoid pesticides which have caused massive bee deaths in the northeastern Pomurje region in the recent weeks. The use of Biscay, a pesticide, will also be limited.

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.

HELEN MURDOCH , Nelson Mail, 1-Apr-2011
It is used for seed dressings, on agricultural crops, soil treatment, compost products, in wood preservatives and in animal flea treatments. But the synthetic neonicotinoid pesticide family is under the spotlight of beekeepers and the Green Party for its possible bee-killing properties.

By Martha Moss - 23rd March 2011
MEPs, scientists and EU officials came together in the European parliament on Wednesday to discuss the potential risks of plant protection products on bees. Speaking at the event, ALDE deputy Chris Davies called on the EU to invoke the precautionary principle in relation to certain pesticides, which could result in their withdrawal from the market were they found to constitute a health risk. Some studies have suggested that neonicotinoid insecticides could be a factor behind Europe's 30 per cent decline in bee numbers seen in recent years.

[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.

A new scientific study that marked honeybees with radio-id chips to measure the impacts of ultra low dose of neurotoxic systemic insecticides on the flight behavior of honeybees found significant effects of the insecticide fipronil (marketed under the names Mundial, Goliath, Regent TS and produced by BASF) on the number of foraging flights and on the time to return to the hive.
The experiment was carried out in a outdoor tunnel (8 m x 20 m, 3.5 m high) covered with an insect-proof cloth (2 mm 9 2 mm mesh) and a ground covered with plastic. The distance between the hive and the sucrose syrup feeder was 18 meter.
The median lethal dose of fipronil is 6 nanogram per honeybee. In this experiments the bees were given a single one-time ultra low dose which is twenty times below the deadly dose: 0.3 nanogram fipronil per honeybee.
The researchers found that even this single ultra low dose significantly reduces the number of foraging trips of honeybees. They also observed that their time to return to the hive increased with 30 seconds. The percentage of bees returning within one minute reduced from 77% (no treatment) to 51% (0.3 ng fipronil per bee). Earlier studies (e.g. Yang e.a. 2008)where bees were marked with paint in stead of radio-id chips and counting and measuring was done by humans with stopwatches observing the bees at the hive and the feeder showed similar effects for imidacloprid. The radio-id chip method enables much more precise analysis of the so called sub-lethal (sub=below, lethal=deadly) effects of pesticides on pollinators.
In The Netherlands the systemic insecticide fipronil is authorised for seed coating and phytodrip in (Dutch crop names) Chinese kool, bloemkool, boerenkool, broccoli, rodekool, savooienkool, spitskool, spruitkool and wittekool to protect these cabbage crops to damage by the cabbage fly (koolvlieg), and for the elimination of cockroaches.
Fipronil is systemic, it enters the plantsap and contaminates pollen and nectar of treated plants and also of nearby growing wild flowers, trees, and weeds and contaminates water on which honeybees forage.

New fears over bee declines
Around the world, losses of bee colonies and wild pollinators continue. Emerging explanations are complex and call for more research, but the case against systemic pesticides is gaining strength. Michael Gross investigates.
Read the full article in Current Biology 22 Feb 2011