This question was already asked by me at Gardening Stack Exchange, but I was advised to ask it here instead. I see there is already a closely related question: Do animals have different taste preferences within the same species? . However, I would like some bee-specific clarification or study material, if possible.
I live in Europe, and planted several supposedly bee-attracting, but non-native (originate from Americas) perennials, most notably:
For all species, I chose several cultivars, for the sake of experimenting.
Although all three species are listed as bee-attractive, bees at my place like only echinaceas and hellenuims. They totally ignore rudbeckias! Is there any plausible explanation for this?
Can it be that european bees are just not used to rudbekias, or simply don't like it, while american bees do?