>Which
>begs the question, what can these growers do to encourage wild
>pollinators?  Does anyone have sets of specifications for nest
>structures to attract solitary bees?  I guess I am looking for a
>FAQ on wild pollinators for the east coast.  I know the
>generalities on habitat and pesticide use, but I am looking for
>specific information on nesting structures to work up into a simple
>fact sheet for farmers.
 
My own perspective? For twig-nesters such as some Osmia, you can put out
blocks of wood with deep holes of various diameters drilled in them (the
more variety in diameters, the more different species one might get to
nest). However, since the majority of native pollinators nest in the ground
(including those which are specialists on cucurbits, as in your present
case), there aren't really any "nesting structures" one can make for them.
What you need is just some bare or semi-bare ground that drains well, for
the most part. When you *study* native ground-nesters, as I do, it's easy
to look at a patch of soil and say "Aha, *that* looks like a promising spot
for bee nests!" - and what that typically entails is an area, often sloping
somewhat, where there is some ground cover, but not completely obscuring
the surface like a lawn. Different bees will have different preferences for
cover, varying down to zero. Sandy soil that drains well probably is
preferred by more species, though some will happily dig in clayey soil.
        I'd say that the problem of nesting sites is the main reason native
pollinators are used so infrequently - the logistics and practicality of a
hive arrangement offer immediate payoffs despite the inefficiency of the
honeybee as a pollinator, while trying to "culture" native bees in a patch
of ground is likely to be a long process. The growers using the Alkali bee
manage to dig up and transport huge chunks of soil containing prepupae, but
this is a pretty heavy-duty operation, trying to move cubic yards of soil
intact. Even if you set out artificial soil blocks, they'd still be heavy
and cumbersome, and enticing bees to nest in them in any useful density
could be a real trick. If the scale of the agriculture were smaller it
would be different, but trying to have several hundred acres of melons will
require unnaturally high numbers of bees - and some ground will have to be
sacrificed for them to nest in.
        I hate to sound so discouraging, but the practical aspects of most
native bees leave a lot to be desired, given their nesting habits. Given
the thousands of species out there, though, at least there should be a
number of options to be explored, some of which may work out better than
others. Other than blueberries, orchard crops, and alfalfa, though, I can't
recall any other jobs for people to evaluate native pollinators in recent
years, so there's clearly not much demand yet for this research.
Cheers,
 
Doug Yanega      Illinois Natural History Survey, 607 E. Peabody Dr.
Champaign, IL 61820 USA     phone (217) 244-6817, fax (217) 333-4949
  "There are some enterprises in which a careful disorderliness
        is the true method" - Herman Melville, Moby Dick, Chap. 82