Science - April 1, 2010

Dusting off museums for bee research

Alterra and the European Invertebrate Survey in Leiden are going to dust off their museum collections in search of old pollen. Researcher David Kleijn wants to get an impression of the food that was available to wild bees over the past few centuries.

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The big dust-off is part of a larger research on the scale and causes of the decline of the honey bee, financed by the ministry of LNV. The researchers are trying to find out whether the decline in bee numbers in recent years has been caused by changes in vegetation and landscape. It is known for example that there is much less clover, an important plant for bumble bees, than there was a century ago.

Vitality
Last year LNV allocated one million euros to a research programme that will investigate the causes of the alarming drop in bee numbers. The Dutch Centre for Bee Research (NCB) is going to measure the death rate in beekeepers' hives, while ecologists will try to get the measure of the decline in wild bee populations. 'We are also doing in-depth research on the vitality of bee populations, diseases, food and beekeeping', says Sjef van der Steen of Plant Research International.
Varroa destructor
Van der Steen is going to research the diagnosis of bee diseases, and identify the role of the Nosema ceranae parasite and environmental factors, particularly genetic diversity, in the high death rate. His colleague Tjeerd Blacquiere will research the influence of the Varroa destructor mite.

Pesticides
The cause of the high death rate in bee populations is far from clear. Two explanations are doing the rounds: one points the finger at the Varroa mite as the chief disease carrier, while the other blames high concentrations of pesticides in the natural environment. Van der Steen: European bee researchers are convinced that the Varroa mite and wrong beekeeping techniques are the main reasons for the bee death rate. This was clear last week at a scientific conference in Germany. On the other hand, there is a group of researchers who firmly believe that pesticides play a role, and this possible cause has been the subject of French and German studies. Ninety percent of the bees have been found to carry pesticide residues, but no link with the death rate has been proven.'

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