the bee used the "buzz" to shake the anthers from their base and collect the falling pollen grains. in that manner they don't need to interact directly with the anthers as honey bee.

Hi,

From my experiences with bumble bees at Cucurbita pepo, worker bees do not like to collect the large spiny pollen grains of squashes and pumpkins. They will visit flowers for nectar, but I will often see worker Bombus on the side of a flower or on a leaf discarding pollen from their legs. I hope this helps. All the best. Blair

Blair's answer is very interesting, because it suggests that the bumblebees did not want to collect the spiny pollen of cucurbits. An alternativ interprepation of this behavoiur - discarding the pollen grains from the legs - is that the bumblebees are unable to store the pollen grains in the corbiculae (as described by Lunau K, Piorek V, Krohn O, Pacini E (2015) Just spines  ̶  Mechanical defence of malvaceous pollen against collection by corbiculate bees. Apidologie. 46: 144-149) . However, Jannik's question is whether the trichomes of Cucurbita flowers trigger pollen collection behaviour and might be interpreted as a tactile (and chemical?) pollen-mimicking stimulus.