DNA testing reveals the true origins of honey

DNA testing of Australian honey can reveal where it was produced and its main floral sources, according to researchers from CSIRO, The University of Melbourne and Curtin University. The findings, published in the journal Ecology and Evolution, could be used for a honey certification program to confirm the floral composition and provenance of commercial honey, which should benefit the $100 million Australian honey industry.

The researchers used a technique called pollen DNA metabarcoding, which is a way to identify plant species from their pollen by sequencing a short stretch of DNA and comparing it with a reference library. The libraries are built using reference DNA of plant specimens, curated by botanical experts at collections like the Australian National Herbarium.

The technique works because honey contains DNA from the pollen collected by bees, and has been described as a fast and accurate way to identify the floral composition of Australian honey. This is unlike the traditional method of using microscopy to identify pollen in honey, said CSIRO’s Dr Liz Milla, which is “time-consuming, requires significant expertise because Australia has such diversity of unique plants, and often can’t identify plants to species level”.

“We tested 15 different honeys from across Australia and found most were dominated by eucalypts and related plants in the Myrtaceae family,” Dr Milla said.

“We detected the major floral source on the label in all commercially produced honeys. In 85% of samples they were found in the top five most abundant floral components. All of the honeys were composed of mixed florals, which reflects the diverse natural diets of honeybees.

“We found that honeys from eastern and western Australia were easy to tell apart and we could categorise most honeys according to Australia’s 89 geographically distinct bioregions from which they came.”

Image ©Liz Milla

Not only can pollen DNA metabarcoding be used to check the composition and provenance of honey, it could be used to help honeybees by monitoring their diets.

“Making sure that honeybee colonies have access to nutritious flora could help build resistance to colony collapse disorder, a phenomenon that has impacted honeybees overseas,” Dr Milla said.

CSIRO researchers are also using the technique to survey flowering plants.

“Honeybees are great field scientists,” Dr Milla said. “We can use them to survey plant species in remote or hard-to-reach places. Bees bring pollen from the plants back to the hive and we can identify the plants from the honey.”

CSIRO is currently working with partners to create a DNA barcode library for all of Australia’s half a million plant and animal species. The library will enable fast, cheap environmental monitoring as well as projects to study bees.

Top image ©CSIRO, David McClenaghan

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