[Something like Pencap-M would be the poison to use, as it does not kill
the forager, but allows the forager to deliver the poisoned "nectar"
back to the colony. The "microencapsulated" nature of the pesticide
is exactly what made it so deadly to bee colonies placed near crops
treated with Pencap-M.]
That's exactly what you need, something that the bees will put away in their stores!!
That way when you establish colonies in the area and rob those poisoned stores it will kill your bees too!!!
Not to mention a totaly violation of the law if you don't have an applicators license (if you did, I doubt you'd be asking these sorts of questions because you'd be school'd to know better.)
There is not a method to sterilize a bee yard.
True isolation is reserved to mid-ocean islands at best.
Bees can fly miles on a 'normal' day, on the wind you can tack a few more on.
If I lived ANYWHERE near you, and I had any ounce proof you were openly poisoning any bees I'd be sure to haul your ***** into court and sue you in any way possible and who ever sold you the product too.
As if CCD, viruses, and soil residual pesticides weren't enough, let's saturate the bee's honey with poisons too!! Good god, where is the decency?
You just might want to consider some methods that use better stewardship toward bees and not a kill 'em and let god sort 'em out mentality.
It would take you longer, but consider saturating the area with desirable genetics. Then you'd improve your yard, and local feral populations too.
Else, unless you instrumental inseminate, you are bailing a sinking cruise ship with a coffee cup.
[IN Licensed Exterminator]
There is always more than one way to skin a cat, that's of course if you're into eating cats.