Honey bees disappearance linked to human shortcuts in honey production
Two separate research reports recently released in the US have pointed to a number of causes for the serious decline in bee numbers that is threatening US agriculture and food supplies globally.
Some of the research was released by the US Department of Agriculture (USDA) and the US Environmental Protection Agency (EPA) in the form of a comprehensive report on honey bee health on 2 May 2013. The report found that there are multiple factors playing a role in the decline of honey bee colonies, including parasites and disease, genetics, poor nutrition and pesticide exposure.
“The decline in honey bee health is a complex problem caused by a combination of stressors, and at EPA we are committed to continuing our work with USDA, researchers, beekeepers, growers and the public to address this challenge,” said Bob Perciasepe, Acting EPA Administrator.
It’s what bees eat
Scientists at the University of Illinois have published the outcome of their research in theMarch 2013 edition of the academic journal Proceedings of the National Academy Sciences, and suggested that what bees eat may be an important factor in CCD.
Many commercial beekeepers in the US use honey substitutes such as sugary syrups and sugar water to feed their colonies. But the study’s authors said the new research shows that honey is “a rich source of biologically active materials that truly matter to a bee”. A natural honey diet supports the bees’ genetics to withstand toxins such as many pesticides.
Honey bees play an essential role in agriculture, not only producing honey and beeswax, but also pollinating a vast number of food crops. CCD is a serious problem threatening the health of honey bees and the economic stability of commercial beekeeping and pollination operations in the US and parts of Europe.
An estimated one-third of all food and beverages are made possible by pollination, mainly by honey bees. In the US, pollination contributes to crop production worth US$20-30 billion in agricultural production annually. A decline in managed bee colonies puts great pressure on the sectors of agriculture reliant on commercial pollination services. This is evident from reports of shortages of bees available for the pollination of many crops.
Honey helps bees detox
The University of Illinois research found that 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. These components might not currently be found in honey-substitutes.
Researchers said that many organisms use a group of enzymes called cytochrome P450 monooxygenases to break down foreign substances and compounds usually found in plants, known as phytochemicals. Honey bees, however, have relatively few genes dedicated to this detoxification process.
“Bees feed on hundreds of different types of nectar and pollen, and are potentially exposed to thousands of different types of phytochemicals, yet they only have one-third to one-half the inventory of enzymes that break down these toxins compared to other species,” said May Berenbaum, lead author of the study, and Professor at the University of Illinois.
Previous research had shown that eating honey turns on detoxification genes in bees that metabolise the chemicals in honey, but Professor Berenbaum and her colleagues 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,” Professor Berenbaum said. “It’s a great signal that tells their systems that food is coming in, and with that food, so are potential toxins,” she said.
The research showed that p-coumaric acid turns on not only P450 genes, but representatives of every other type of detoxification gene in the bees’ genome. This signal can also turn on honey bee immunity genes that code for antimicrobial proteins.
Other honey components also medicinal
According to Professor Berenbaum, three other honey constituents were effective inducers of these detoxification enzymes in honey bees. These components probably originate in the tree resins that bees use to make propolis, the “bee glue” that lies in all of the cells and seals cracks within a hive.
“Propolis turns on immunity genes – it’s not just an antimicrobial caulk or glue. It may be medicinal, and, in fact, people use it medicinally too,” Professor Berenbaum said.
Suggested improvements to honey-substitutes
Professor Berenbaum said she hopes that future testing and development will yield honey substitutes that contain p-coumaric acid so beekeepers can enchance their bees’ ability to withstand pathogens and pesticides.
The researchers said they didn’t recommend that beekeepers “rush out and dump p-coumaric acid into their high-fructose corn syrup,” they hoped that the latest research can be used as the basis for future work aimed at improving bee health.
“If I were a beekeeper, I would at least try to give them some honey year-round,” Professor Berenbaum said. “Because if you look at the history of Apis mellifera [European honey bees], 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,” she said.