Bijensterfte, oorzaken en gevolgen

On 30 March 2012 Science published 2 studies and a comment on neonicotinoid insecticides and pollinator decline:

- A Common Pesticide Decreases Foraging Success and Survival in Honey Bees
- Neonicotinoid Pesticide Reduces Bumble Bee Colony Growth and Queen Production
- Field Research on Bees Raises Concern About Low-Dose Pesticides

A Common Pesticide Decreases Foraging Success and Survival in Honey Bees
Non-lethal exposure of honey bees to thiamethoxam (neonicotinoid systemic pesticide) causes high mortality due to homing failure at levels that could put a colony at risk of collapse. Simulated exposure events on free-ranging foragers labeled with an RFID tag suggest that homing is impaired by thiamethoxam intoxication. These experiments offer new insights into the consequences of common neonicotinoid pesticides used worldwide.
Read full paper: A Common Pesticide Decreases Foraging Success and Survival in Honey Bees

Neonicotinoid Pesticide Reduces Bumble Bee Colony Growth and Queen Production
Growing evidence for declines in bee populations has caused great concern due to the valuable ecosystem services they provide. Neonicotinoid insecticides have been implicated in these declines as they occur at trace levels in the nectar and pollen of crop plants. We exposed colonies of the bumble bee Bombus terrestris in the lab to field-realistic levels of the neonicotinoid imidacloprid, then allowed them to develop naturally under field conditions. Treated colonies had a significantly reduced growth rate and suffered an 85% reduction in production of new queens compared to control colonies. Given the scale of use of neonicotinoids, we suggest that they may be having a considerable negative impact on wild bumble bee populations across the developed world.
Read full paper: Neonicotinoid Pesticide Reduces Bumble Bee Colony Growth and Queen Production

Field Research on Bees Raises Concern About Low-Dose Pesticides
Five years ago, bees made headlines when a mysterious condition called colony collapse disorder decimated honey bee colonies in parts of the United States (Science, 18 May 2007, p. 970). Now bees are poised to be in the news again, this time because of evidence that systemic insecticides, a common way to protect crops, indirectly harm these important pollinators. Two fi eld studies reported online this week in Science document problems. In bumble bees, exposure to one such chemical leads to a dramatic loss of queens and could help explain the insects’ decline. In honey bees, another insecticide interferes with the foragers’ ability to find their way back to the hive.
Researchers say these fi ndings are cause for concern and will increase pressure to improve pesticide testing and regulation. “It’s going to cause an absolute fi restorm,” predicts James Cresswell, an ecotoxicologist at the University of Exeter in the United Kingdom, who was not involved in the research.
Bayer CropScience, the main producer of systemic pesticides, maintains that its products are not a culprit in honey bee declines, and many independent experts aren’t convinced by the evidence against pesticides, adding that pathogens and parasites are the main problem.
Read full paper: Field Research on Bees Raises Concern About Low-Dose Pesticides

Neonicotinoids are highly persistent neurotoxic insecticdes from the organochlorine family of chemicals. The most widely used neonicotinoids are imidacloprid, clothianidin, thiamethoxam and thiacloprid. These insecticides act systemic: the substance is taken up by the roots of plants (including non-treated wild plants) making them toxic to insects from the inside. Key food sources of pollinators such as nectar, pollen, guttation, honeydew and surface water also get contaminated with residues of these ultra toxic chemicals.

References
Erik Stokstad (2012)Field Research on Bees Raises Concern About Low-Dose Pesticides Science 335 (6076) 1555
http://dx.doi.org/10.1126/science.335.6076.1555

Mickael Henry, Maxime Beguin, Fabrice Requier, Orianne Rollin, Jean-Francois Odoux, Pierrick Aupinel, Jean Aptel, Sylvie Tchamitchian, Axel Decourtye (2012) A Common Pesticide Decreases Foraging Success and Survival in Honey Bees Science 1215039
http://dx.doi.org/10.1126/science.1215039

Penelope R. Whitehorn, Stephanie O’Connor, Felix L. Wackers, and Dave Goulson (2012) Neonicotinoid Pesticide Reduces Bumble Bee Colony Growth and Queen Production Science 1215025.
http://dx.doi.org/10.1126/science.1215025