I believe in taking 'sources' that you know are good in the area, or that you want them to use, and putting them by the entrance of the hives, like right at it, helps train them to accept those sources. bees do not need anyone to do that of course, they do just fine on their own, but if you took that banana nectar, and took a banana flower (great in some recipes btw if you haven't used them to cook with.) and placed it right at the entrance, not blocking it but there and in the early morning put nectar on it, it will train them to find it, and harvest from it. do it for a few mornings. like I said though they do not really need you to do it, though.
bee response can be trained though, and it is found that different bees in a hives react differently to different responses also, I believe. scientists do this type of training to get bees to find explosives/etc. even. though they do it by a reward system where they pipe scent towards the bees and the ones that respond to the scent, a scent for a particular explosive/etc, they reward with nectar on a qtip. Bees train extremely fast, from what I am to understand. in less then a few hours even. doing the above is the same in the respect that you are rewarding them with the nectar right there and they will train on the scent.