Monday, 3 August 2015

Bumblebee pollen collection

I wrote last week about the unusual technique employed by buff-tailed bumblebees to harvest pollen from poppies. Female bumblebees and honey bees collect pollen in specially adapted hairs on their hind tibiae which form a pollen basket or corbicula.  This is absent in males and in cuckoo bees which do not collect pollen.  Below you can see the shiny hairless pollen basket on the tibia (the upper section of the visible back leg here) of a bumblebee.


Rusty Burlew wrote a great description of how the bees get the pollen into the basket in a recent post on her blog.  The pollen basket is filled from below so when pollen collection has only just started the pollen is at the bottom of the tibia.



As the basket fills it holds a surprising amount of pollen without the pellet falling off.  I wonder how she knows when it's full?

Honey bees and some solitary bees exhibit flower constancy, that is each bee pretty much sticks to one type of flower at a time.  That is confirmed by finding only one colour in the pollen basket.


Bumblebees are more likely to visit different types of flower on one visit, as is easy to see from the multicoloured pollen in their pollen baskets.






3 comments:

  1. So is the pollen under a translucent membrane we can see the colour through?

    ReplyDelete
    Replies
    1. No Phil, there is no membrane. It is just pollen. Although pollen is produced in individual grains, when they cover the bee's body she scrapes them all to her hind legs and then uses the joint to squeeze them into a pollen pellet. Have look at http://www.honeybeesuite.com/how-the-honey-bee-makes-pollen-pellets/ for a full description. I suppose it's a bit like snowflakes being made into a snowball. The pellet is held in place by the hairs around the edge of the pollen basket that look a bit like a comb (as you can see on the last photo above) and I guess it may also stick onto the smooth surface of the tibia. It looks precarious but it works.

      Delete
  2. An amazing, colourful and interesting collection of photos. Obviously a perfect design for the task in hand.

    ReplyDelete