Galloway lab shows pollinator visits can depend on pollen color.

You can read about it here.

Ison, J. L., Tuan, E. S. L., Koski, M. H., Whalen, J. S., & Galloway, L. F. (2018). The role of pollinator preference in the maintenance of pollen colour variation. Annals of Botany, 123(6), 951–960. doi: 10.1093/aob/mcy211