Why the bumblebees the best pollinators for greenhouse?
The bumblebees create some vibrations of flower and air around the flower. This process calls "Buzz-pollination".
Here you can download little film about "Buzz-pollination".(MOV, 588 Kb)
 
The bumblebees not so aggressive lice honeybees
 
The bumblebee's body has more hair, and they take a lot of pollen from one plant to another. And as result of that pollination process will be more effective.
 
The bumblebees hasn't the "language of dance", and work of bumblebees more successful in greenhouse in blossom period in outdoor.
 
The bumblebees has more better orientation in greenhouse than honeybees
 
The pollen from tomatoes satisfy bumblebees, but for honeybees this pollen not so nourishing.
 
When the hive of bumblebees goes to the greenhouse, bumblebees can long time live inside the hive without flying, but honeybees can't long time to be in the hive without flying.