Bombus terrestris, a bumblebee, at work in my garden visiting P. 'Betty Myles Young'. It is just beginning to be dusted with pollen which it will carry to the next flower it visits. They will typically try to collect pollen from just one type of flower so there must be some passion flower honey nearby! Bees visit plants both for pollen and /or nectar & rarely oil. As we all know they are common pollinators for many plants, many of the Passiflora I grow attract them. Exceptions include red flowers such as P. murucuja & Tacsonia & also P. suberosa.
Research at Southampton University by Jane C. Stout et al has found that bumblebees & honeybees scent-mark flowers that they have visited with a mutually repellant chemical, with the effects wearing off after a day. Both also use a short term chemical marker which wears off after about 40 minutes, giving the flower time to replenish its nectar. Honeybees also label productive flowers with another longer lasting scent, so they can find & revisit them the next day.