Bijensterfte, oorzaken en gevolgen

By Toshiro Yamada, Kazuko Yamada and Naoki Wada, Jpn. J. Clin. Ecol. （Vol.21 No.1 2012)
Abstract 　Recently it has become a serious problem that honeybees suddenly vanish in their colony, which is referred to as a colony collapse disorder（ CCD）. We have made it clear by the field experiments for about four months what effect neonicotinoid pesticides such as dinotefuran and clothianidin have on the occurrence of CCD. Eight colonies consisting of about ten-thousand honeybees in each colony were investigated under the practical beekeeping conditions in our apiary. In this study foods containing dinotefuran of 1 ppm to 10 ppm or clothianidin of 0.4 ppm to 4 ppm were fed into a beehive. Three levels of concentration were 10（ high-conc.）, 50（ middle-conc.） and 100 low-conc.） times lower than that in practical use. The changes of adult bees, brood and the pesticide intake in each colony were directly examined. They suggest that each colony with the pesticide administered collapses to nothing after passing through a state of CCD, the high-concentration pesticides seem to work as an acute toxicity and the low- and middle-concentration ones do as a chronic toxicity. CCD looks mysterious, but it is just one of situations where a colony dwindles to nothing. We have proposed a CCD occurrence mechanism based on our results.
The NMR spectral analyses of dinotefuran and clothianidin in aqueous solution give the speculations that both are thermally stable under the heating condition of 50 ℃ ×24 hours and dinotefuran is radiationally stable under the ultraviolet-irradiation condition of 310 nm×50 W/m2 but clothianidin is unstable.

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."

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

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.

Stefano MAINI, Piotr MEDRZYCKI, Claudio PORRINI, Bulletin of Insectology 63 (1): 153-160, 2010

The impact of pesticides on honey bees is an issue that has been studied for many years and is now being reconsidered because controversy still exists with the relationship of insecticides and Colony Collapse Disorder (CCD). It is insufficient to explain CCD with only bee pathology studies. Research must be conducted on a wider series of causes: i) in open field and agroecosystems, to understand the fate of pesticide blends, ii) in the hives, to determine ways to enhance honey bee defence to diseases and parasites. References regarding imidacloprid and CCD in the maize agroecosystems are critically reviewed. Pesticides and the thechniques to rationally use them (in particular following the integrated pest management guidelines) represent one of the several puzzles regarding the mystery of CCD or honey bee vanishing. An appendix, i.e., a rejected letter to Science and relevant reply, is also reported.

Full paper: http://www.bulletinofinsectology.org/pdfarticles/vol63-2010-153-160maini...

April 22, 2010

Dennis vanEngelsdorp[1], Jerry Hayes[2], Dewey Caron[3], and Jeff Pettis[4].
This is a preliminary analysis, and a more detailed final report is being prepared for publication at a later date.

The Apiary Inspectors of America (AIA) and USDA-ARS Beltsville Honey Bee Labconducted a survey to estimate winter colony loses for 2009/2010. Over 22.4% of the country’s estimated 2.46 million colonies were surveyed.A total loss of 33.8% of managed honey bee colonies was recorded. This compares to total losses of 29%, 35.8% and 31.8% recorded respectively in the winters of 2008/2009, 2007/2008 and 2006/2007.

[Maxim and Van der Sluijs 2010, Environmental Research Letters]

French researchers estimate that 73% of the increased colony collapse in 1994-2004 in areas of extensive agriculture in France has been caused by imidacloprid.

In hives affected by Colony Colapse Disorder (CCD), first observed on sunflowers in France, there may only be a few bees around the queen, or none at all. Bees are not seen leaving the hive, and where they go is a mystery. Clinical evidence for hives collapsing due to disease pathogens such as the varroa mite, Nosema ceranae or viruses is lacking. Varroa and its proliferation in hives is clearly visible with the naked eye, but the hive does not disappear so quickly as those affected by CCD. A correlation between the varroa infestation level of an apiary and the disappearance recorded has not been demonstrated. Bees in apiaries infested by Nosema ceranae do not have the key symptom: diarrhea. The Acute Paralysis Virus is too virulent and would kill the infected bee before contaminating other hosts or vectors. An infection with the Deformed Wing Virus is clearly visible (atrophied wings and a small stomach) and does not explain the rapid collapse of hives during sunflower harvesting.

Vertaald uit het Frans door Henk Tennekes (oorspronkelijke Franse tekst)

Voor de eerste keer komt in de wereld van wetenschap en bijenteelt overeenstemming bovendrijven over de doodsoorzaken die voor bijenvolken in de meeste werelddelen van invloed zijn. Deze wending is waarneembaar op het congres Apimondia in Montpellier, waar van dinsdag 15 tot zondag 20 september 500 bijenspecialisten en 10.000 deelnemers bijeenkwamen. De wetenschappers spreken nu van een „multi-factorieel“ verschijnsel. De verschillende factoren zouden om de beurt verantwoordelijk kunnen zijn voor de sterfte – die niet in alle landen noodzakelijkerwijs dezelfde oorzaken heeft. Maar vooral moet de mogelijkheid van onderlinge wisselwerkingen zeer serieus worden genomen. Volgens deze theorie wordt de honingbij door een reeks stress (varroa mijt, gebrek aan water door klimatologische verandering, chronische blootstelling aan pesticiden, onvolwaardige voeding) „primair“ getroffen. Virussen en schimmels zouden “secundaire” factoren zijn, die van de zwakte van de honingbijen profiteren. Een andere potentiële bron van problemen is het bestaan van een wereldwijde markt van bijenkoninginnen, die de meest productieve soorten bevoorrecht ten koste van soorten die aan de plaatselijke omstandigheden zijn aangepast, waardoor ook de genetische verscheidenheid minder wordt. Deze uitwisseling bevordert bovendien de verspreiding van ziektes en parasieten.

PULLMAN, Washington, July 29, 2009 (ENS) — A microscopic pathogen and pesticides embedded in old honeycombs are two major contributors to the bee disease known as colony collapse disorder, which has wiped out thousands of beehives throughout the United States and Europe over the past three years, new research at Washington State University has confirmed.

In het Juni 2009 nummer van het Franse INRA magazine (L'Institut National de la Recherche Agronomique) staat een artikel "Le déclin des abeilles, un casse-tête pour la reche; dossier central". Zie:
www.inra.fr/content/download/16788/277180/version/2/file/inra-magazine-9.pdf.

Figuur 1: Bijensterftecijfers volgens Bijenmonitor Coloss. De rode balkjes geven het totale percentage van de volken in de monitor die die de winter niet overleefden. De grijze balkjes geven het percentage aan waarbij de verschijnselen met CCD overeenkwamen.

1. Inleiding
Over bijensterfte verschenen de afgelopen maanden talloze publicaties in de media, informeerde de minister van LNV de kamer, discussieerden imkers op het imkerforum van Bijenhouden.nl. , en kon de omvang vanaf april real-time gevolgd worden op www.beefriends.org. Niet alleen het sterftecijfer bleek van belang, maar ook hoe dit geïnterpreteerd moet worden. Is een hoge sterfte een natuurlijk verschijnsel dat zich zo af en toe voordoet en dat bijen zelf oplossen in de zwermperiode of is er sprake van een structureel probleem waarbij bijensterfte een indicator is van problemen die een grotere reikwijdte hebben? Daarbij werden door de media met name klimaatveranderingen en straling door zendmasten opgepakt. Vanuit imkerzijde werd gewezen op het gebruik van pesticiden in de landbouw, door gemeentelijke diensten en door particulieren.
Naast het leveren van zo goed mogelijke cijfers en argumenten voor deze publieke discussie is onze invalshoek het vaststellen van de dynamiek van bijensterfte in omvang en verspreiding om te kunnen evalueren of maatregelen die worden genomen zinvol zijn, en of er verschillen tussen dode volken te onderscheiden zijn die kunnen verwijzen naar verschillende ziekteverwekkers . In de vragenlijsten van 2007 en 2008 hebben wij met name onderzocht of sterfte met kenmerken van CCD (Colony Collapse Disorder) te onderscheiden viel van andere bijensterfte. CCD wordt in Nederland vaak omschreven met ‘verdwijnziekte’. In dit artikel gebruiken wij verder de term CCD.

Dutch summary: De voedingswaarde van stuifmeel (vooral het eiwitgehalte) beinvloedt de levensverwachting van bijen. Een te eenzijdig dieet van stuifmeel met een laag eiwitgehalte zou een rol kunnen spelen bij bijensterfte. Zie ook www.bieenkorf.be/bijensterfte.pdf voor Nederlandstalige informatie over deze factor.

Pollen Power
by: Joe Traynor, February 01, 2009

Not all pollens are created equal.

All beekeepers are aware that protein is a key constituent in a healthy bee diet – honey provides the carbohydrates, pollen supplies the protein. When it comes to pollen, though, not all pollens are created equal [1,2,3].

Volgende week vrijdag is er een documentaire van de BBC Who Killed the Honeybee over de wereldwijde bijensterfte.
Uitzending is op 15 mei, BBC 2, 20.00 uur Nederlandse tijd.
Zie de BBC website voor meer informatie. Tip: meestal zijn BBC documntaires na uitzending een week lang online te bekijken op hun site.
(Met dank aan Johan die het melde op Imkerforum)

The mysterious ailment called colony collapse disorder has wiped out large numbers of the bees that pollinate a third of our crops. The causes turn out to be surprisingly complex, but solutions are emerging.

* Millions of beehives worldwide have emptied out as honeybees mysteriously disappear, putting at risk nearly 100 crops that require pollination.
* Research is pointing to a complex disease in which combinations of factors, including farming practices, make bees vulnerable to viruses.