Hello Aaron & All,
 Frankly I can't say.  I had a neighbor intentionally poison the bees
robbing
 a stack of wet supers in October and attribute heavy winter losses to the
 incident.  All my hives (50) within flying distance of the poisoned supers
 are dead this spring.
Sadly this situation happens all to often.  Happened to a friend of mine in
Texas.  Lost the whole yard. Most the time you don't know what happened to
your bees.  His bees were robbing at a honey house of another beekeeper
which didn't keep bees at his extracting area.   The beekeeper put out
tainted honey.  All the beekeeper said when asked about the incident was.
"You shouldn't have set your bees so close and he didn't think the bees
would fly all the way back to my friends hives before dying."  My friend was
VERY upset and doesn't keep bees close to the other beekeeper now.   I
personally would NEVER do such a thing but there are beekeepers which will.
The idea is if the bees robbing do not make it back to the hive then others
will not come and eventually the problem will stop.   Aarons bees were to
close so (like my friends ) all his hives died.  If Aarons hives had been
farther away they would be low in populations instead of dead and Aaron
would have been wondering why.
Sorry for your loss Aaron.  Like all things beekeeping has a few bad apples.
Sincerely,
Bob Harrison
Odessa, Missouri