Flowers are the main (and in most cases, the only) source of food for bees. But it’s not their only role in bees’ lifes. They can have also a medicinal value, helping bees to get rid of various pathogens. One of examples is pollen of sunflowers. It helps bumblebees fight the infection by Crithidia bombi, their protozoan pathogen. The mechanism of this beneficial effect was unclear, as scientists could not identify any chemicals present in sunflower pollen which would kill the pathogens. It turned out that there might be none… but the pollen works like a laxative, cleaning the digestive tract from the pathogen’s spores.
Here you can read about the study: Adler, L. S., Fowler, A. E., Malfi, R. L., Anderson, P. R., Coppinger, L. M., Deneen, P. M., … & Stevenson, P. C. (2020). Assessing chemical mechanisms underlying the effects of sunflower pollen on a gut pathogen in bumble bees. Journal of chemical ecology, 46, 649-658.
Non-honey bees 