|Pollen collection system (from the study)|
The current pollen demand for human nutrition has drastically increased due to its therapeutic value, with potential for medical and nutritional applications. Pollen pellets collected by honeybees (Apis mellifera L.) contain proteins, all the basic amino acids, carbohydrates, lipids, such as Omega-3 and Omega-6 fatty acids, vitamins and minerals. Based on the presence of these compounds, pollen is eligible as human food, and national pollen standards exist in a number of countries. Consequently, many beekeepers have transitioned their interests to pollen collection, and currently, the global pollen production is approximately 1500 tons per year, with Spain the most important producer.
Honeybees tirelessly fly from flower to flower collecting thousands of pollen grains that adhere to the tiny hairs on the back of their hind legs while using a bit of nectar from their stomach to help pack the pollen into pellets. Carrying two pellets at a time they travel back to the hive with their bounty and feed it to their young.
Beekeepers sometimes attach a small box fitted with a screen in the doorway of a hive to allow the bee to enter but harmlessly remove the pollen granules from their legs. Beekeepers have to be careful to collect only a small amount from any given hive, so as not to deprive the bees of this important food source for their young. The collected pellets are then either sold fresh, or frozen or dehydrated.
Pollen composition and the diversity of its source directly influences the quality and safety of all honeybee products. Not long ago I published a post on a study that looked at antibacterial effects of honey and a similar study appeared a few days ago. The identification of plants visited by honeybees is of fundamental importance for beekeepers to assess the quality of their products, and guarantee the consumer of product safety. In addition, the geographical origin of pollen strongly affects its commercial value.
As shown in the earlier studies, DNA Barcoding is perfectly suited to help with such analyses. Reason enough for a team of Italian researchers to put the pollen to the test. By the way, they also published one of the studies I mentioned above.
The team collected pollen pellets using modified beehives placed in three zones at different altitude within the Grigna Settentrionale Regional Park in Italy. The park is a protected area in the Bergamo alps. In order to test the plant composition of collected pollen pellets the authors assembled a DNA barcoding reference libray including rbcL and trnH-psbA sequences of 693 plant species representing about 45% of the entire flora of the region.
Needless to say, they have been very successful and they were able to document substantial variability in pollen composition between higher and lower altitudes as well as between seasons. Overall, they were able to find 52 different plant species in the pollen collected and among those, nine were rare and in some cases endemic species. At one site, the pollen contained known alien species, such as Lonicera japonica and Pelargonium x hortorum. The colleagues conclude:
Our results indicated pollen composition was largely influenced by floristic local biodiversity, plant phenology, and the presence of alien flowering species. Therefore, pollen molecular characterization based on DNA barcoding might serve useful to beekeepers in obtaining honeybee products with specific nutritional or therapeutic characteristics desired by food market demands.