Substances in honey increase detoxification gene expression

University of Illinois News Bureau: Research in the wake of Colony Collapse Disorder, a mysterious malady afflicting (primarily commercial) honey bees, suggests that pests, pathogens and pesticides all play a role. New research indicates that the honey bee diet influences the bees’ ability to withstand at least some of these assaults. Some components of the nectar and pollen grains bees collect to manufacture food to support the hive increase the expression of detoxification genes that help keep honey bees healthy.

...University of Illinois professor of entomology May Berenbaum, who led the study, said that many organisms use a group of enzymes called cytochrome P450 monooxygenases to break down foreign substances such as pesticides and compounds naturally found in plants, known as phytochemicals. However, honey bees have relatively few genes dedicated to this detoxification process compared to other insect species, she said.

...Research had previously shown that eating honey turns on detoxification genes that metabolize the chemicals in honey, but the researchers wanted to identify the specific components responsible for this activity. To do this, they fed bees a mixture of sucrose and powdered sugar, called bee candy, and added different chemical components in extracts of honey. They identified p-coumaric acid as the strongest inducer of the detoxification genes.

“We found that the perfect signal, p-coumaric acid, is in everything that bees eat – it’s the monomer that goes into the macromolecule called sporopollenin, which makes up the outer wall of pollen grains. It’s a great signal that tells their systems that food is coming in, and with that food, so are potential toxins,” Berenbaum said.

Her team showed that p-coumaric acid turns on not only P450 genes, but representatives of every other type of detoxification gene in the genome. This signal can also turn on honey bee immunity genes that code for antimicrobial proteins. According to Berenbaum, three other honey constituents were effective inducers of these detoxification enzymes. These components probably originate in the tree resins that bees use to make propolis, the “bee glue” which lines all of the cells and seals cracks within a hive.

...Many commercial beekeepers use honey substitutes such as high-fructose corn syrup or sugar water to feed their colonies. Berenbaum believes the new research shows that honey is “a rich source of biologically active materials that truly matter to a bee.” She hopes that future testing and development will yield honey substitutes that contain p-coumaric acid so beekeepers can enhance their bees’ ability to withstand pathogens and pesticides.

...“If I were a beekeeper, I would at least try to give them some honey year-round,” Berenbaum said, “because if you look at the evolutionary history of Apis mellifera, this species did not evolve with high fructose corn syrup. It is clear that honey bees are highly adapted to consuming honey as part of their diet.”...

Bees on a honeycomb, shot by Killerlimpet, public domain