Exactly what plants do honey bees visit on their daily forages for food? At least in rural Madison County, Ohio, scientists know. A research team led by Dr. Reed Johnson from The Ohio State University has found that the answer lies in pollen DNA. They've collected pollen from a trapping device beneath beehives and developed a new method utilizing DNA meta-barcoding to uncover the plants from which the pollen originated.
DNA metabarcoding is a promising alternative because it is a way to rapidly identify the genera or even species present in a mass DNA sample of multiple organisms. The technology has been gaining popularity across many fields of biology because it results in higher sensitivity and resolution, and in this case identified twice as many plant families than microscopic analysis of the same pollen samples. It lacked, however, the ability to quantitatively assess the relative proportions of each pollen type. This will need to be addressed in future advancements.
"Understanding honey bees' pollen preferences can provide insights to what a colony needs and help improve the quality of foraging habitats," says Dr. Chia-Hua Lin, a postdoctoral researcher in the Department of Entomology at The Ohio State University.
Their work will not only provide other researchers with a foundation for uncovering information from pollen DNA, it will also enable bees to do some environmental science fieldwork.
"A honey bee colony is like an army of research assistants--thousands of enthusiastic, flying research assistants that work all day and trespass with impunity," explains Doug Sponsler, a graduate student in the Department of Entomology. While foraging each day, bees are unknowingly monitoring plants in their surrounding landscapes, some hard to reach by researchers, and collecting valuable data in the form of pollen. They can also serve as bioindicators of pollution and pesticides.
Rodney Richardson, a graduate student in The Ohio State University's Department of Entomology, explains that traditional methods of analyzing pollen data under the microscope suffer from being difficult, slow, and often imprecise. "There's a huge bottleneck in the workflow because ultimately every sample needs the undivided attention of one expert behind a microscope," says Richardson. "It's a first attempt that lets other researchers know what to expect, using the ITS2 marker in particular."
For now, a combination of traditional microscopic analysis with DNA metabarcoding offers a deeper look into bee foraging behavior than either method alone. For scientists, it is only the beginning of uncovering the secret life of bees. For the bees, it is only the beginning of their work as research assistants.
Citation: Rodney T. Richardson, Chia-Hua Lin, Douglas B. Sponsler, Juan O. Quijia, Karen Goodell, and Reed M. Johnson. 2015. Application of ITS2 metabarcoding to determine the provenance of pollen collected by honey bees in an agroecosystem. Applications in Plant Sciences 3(1): 1400066. doi:10.3732/apps.1400066.