A short article in the May edition of the BBKA News described an observation project conducted by scientists in Germany. They have presented stunningly-clear video showing some of the usually hidden activities of our bees within their hives.
The brevity of the article belies the importance of these films and the generosity of the scientists who made their findings freely available to other researchers, beekeepers, educationalists and the wider public.
The films clearly demonstrate intricate bee behaviours including nest building, foraging, storing and ripening food, brood rearing, temperature regulation, hygiene and defence. Usually these behaviours, especially those within cells are hidden from sight and are only described in texts and drawings.
In their study, Paul Siefert, Nastasya Buling and Bernd Grunewald (with the support of others) present a rare view of honey bee activities within comb cells and some behaviours never seen before.
Each month, I plan to treat us to a different topic illustrated by these fascinating films but you can see them all immediately by visiting the Plos One website where you will also find more forensic, scientific descriptions of each behaviour. I’ve often wondered how a forager, laden with pollen, removes it from her legs. Well, now I know, so I’ve started here with that!
Unloading and storing pollen In the first two films, we watch older workers recently returned from foraging. They briefly inspects a cell to check its suitability for pollen storage before using their front (prothoracic) legs to cling to the bottom of the adjoining cell.
Then they place their abdomens against the lower wall of the target cell so that the pollen baskets (corbiculae) are positioned near the entrance of the cell leaving the middle legs free.
The middle (mesothoracic) legs are then used to brush along the outer side of the hind legs. The pollen load falls into the cell and she cleans off any remaining pollen in a similar fashion but with quicker movements.
Finally, the worker holds onto the upper cell wall with both the front and middle legs for a final clean-up. The pollen in the cell is then packed-down further with several quick movements of the legs. This process of leg cleaning and pollen packing is repeated several times until the legs are free from pollen.
After the forager has left the cell, younger bees pack the pollen more tightly towards the base of the cell with closed mandibles and upward flicking movements of the head.
The researchers noticed on one occasion, this final packing was done by the same forager re-entering the cell after the pollen was unloaded. That’s one very diligent bee!
Packed pollen is later broken-up and mixed with saliva, nectar and honey to create bee bread.
Nectar storage and uptake In this video we see a worker storing nectar. She crawls into the cell and regurgitates the food from her honey crop. You can see the globule of liquid increasing in size. The researchers noted that the liquid is spread by periodic half-circular movements and if the cell already contains liquid food, the mandibles dip into it.
For the entire duration of the process, the proboscis remains folded and the mandibles are held open. Since food adheres to the upper cell wall and is pulled downwards by gravity, the cell can be evenly filled without the worker targeting the lower half of the cell.
Liquid nourishment from the filled cell is taken up by the proboscis. To me, it looked as if she goes in with her tongue hanging out gasping for a drink! You can see the volume of stored liquid noticeably decreasing.
Visit Plos one for further details of this incredible research.