Hello Inger and All,

>Is use of native bees for pollination common?
no.

Alfalfa leaf cutter bee use is possibly the biggest pollination use for
solitary bees.

I am the only beekeeper in our area  which keeps solitary bees. I raise
Osmia lignaria.

>Is there concern that beekeepers are affecting the native bee >populations
negatively by "supporting" non-native honeybee population?

I do not see this as a problem. I suppose if native bees which forage out a
few hundred feet from the nest were placed near a area of a huge number of
hives then the native bee might suffer.

>I had thought that the different parasites attacking (non-native)
>honeybees in the U.S. in the past few decades had decimated our >native bee
populations also.

 Parasites effect solitary bees but the two main parasites (varroa and
tracheal mites) of honey bees do not I have been told by the USDA lab in
Utah.

Parasites causes problems in Osmia lignaria while the bee is maturing in the
cell.

Sincerely,
Bob Harrison