Nectar robbing bumblebees are detered from visiting and feeding from Aconitum flowers via alkaloids which are more distasteful to nectar robbers than to pollinating honeybees. Obviously, plants can finely control behaviour of insects using mixtures of alkaloids and other non-nutrient compounds enriched within their nectar exudates.
http://www.cell.com/current-biology/abstract/S0960-9822(17)30870-9
http://www.newstatesman.com/culture/nature/2017/08/nectar-robbers-how-flowers-discriminate-against-wrong-kind-bees