“There are agricultural pesticides everywhere,” she said. “They accumulate in the wax of bee hives, so bees in particular are exposed. And their habit of foraging very broadly across a staggering diversity of plant species also tends to expose them to many different types of habitats, which may also have different types of chemical residues.”
Other chemicals are applied directly to the hives, she said. For the past 20 years, beekeepers have used acaricides – chemicals designed to kill mites but not bees – in the hive.
While evidence so far does not support the idea that exposure to synthetic pesticides is a cause or significant contributor to colony collapse disorder, the massive die-off of honey bees first reported in late 2006, “it’s abundantly clear that pesticides aren’t really very good for any insect,” Berenbaum said. “So we figured it was about time somebody knew something about how pollinators process toxins.”
The researchers focused on cytochrome P450s, enzymes that are well-known agents of detoxification “in most air-breathing organisms,” Berenbaum said. Other studies had shown that cytochrome P450s in honey bees play a key role in their tolerance of pyrethroid pesticides, such as tau-fluvalinate, which is used to kill mites in the hive. But no previous study had identified specific cytochrome P450s in bees or in other pollinating insects that contribute to pyrethroid tolerance, Berenbaum said.
In a series of experiments, the team identified three cytochrome P450s in the honey bee midgut that metabolize tau-fluvalinate. They discovered that these enzymes also detoxify coumaphos, a structurally different organophosphate pesticide that also is used to kill mites in bee hives.
The evidence also suggests that honey bees were “pre-adapted” to detoxify pyrethroid pesticides, Berenbaum said. Pyrethroids are similar in structure to naturally occurring defensive compounds, called pyrethrins, produced by some flowering plants. Honey bees have likely had a long history of contact with pyrethrins, which are found even in some flowers in the daisy family. It appears that the same enzymes that helped the honey bees detoxify the pyrethrins in nature may also help them tolerate this relatively new pesticide exposure.
The new findings should enhance efforts to develop mite control methods that are even less toxic to bees, Berenbaum said.
Also on the study team were U. of I. cell and developmental biology professor Mary Schuler and postdoctoral researcher Wenfu Mao.Editor’s notes: To reach May Berenbaum,
Diana Yates | University of Illinois
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The Institute of Semiconductor Technology and the Institute of Physical and Theoretical Chemistry, both members of the Laboratory for Emerging Nanometrology (LENA), at Technische Universität Braunschweig are partners in a new European research project entitled ChipScope, which aims to develop a completely new and extremely small optical microscope capable of observing the interior of living cells in real time. A consortium of 7 partners from 5 countries will tackle this issue with very ambitious objectives during a four-year research program.
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Researchers at the Goethe University Frankfurt, together with partners from the University of Tübingen in Germany and Queen Mary University as well as Francis Crick Institute from London (UK) have developed a novel technology to decipher the secret ubiquitin code.
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Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are less stable. Now researchers at the Technical University of Munich (TUM) have, for the first time ever, produced a composite material combining silicon nanosheets and a polymer that is both UV-resistant and easy to process. This brings the scientists a significant step closer to industrial applications like flexible displays and photosensors.
Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are...
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