Nice shots, but yellow bees on yellow flowers are going to give you a bit of a contrast problem - you take what you can get though. :mrgreen:
In my humble opinion, the third one is the best of the lot (if you number your images it makes it easier for folks to comment on them), however, I would have tried to capture the bee from the other side so that you get more of the bee and less of the flower.
The first one has too much background stuff in it that detracts from the subject and the bee is lost in the petals. The second one is a bit better, but still too much background stuff. Also, I would have tried to get lower so you are shooting at the insects level rather than shooting from above - the perspective from being at the same level as the bee will be much better.
WesternGuy