I don't really know much (or anything) about that. But I haven't noticed any change of behaviour on bees coming onto my garden. The only change is when I remove one of the plants they like to lick they stop coming... So am currently working on having a bee free garden for next summer by having all those plants/flowers identified and removed.
Now go suck my "magnets" you bees (and wasps)!
I can understand not wanting wasps but whats wrong with Bees?
I noticed Bees missing about 3 years ago and a small green metallic fly was pollinating my berry bushes so i guess life is not quite as fragile as we think. Last year i had some "Queens Bees" start showing up.