I'm up for the challenge, though we both have to realize that few commercial orchards/crops are ready for
permaculture. When one has thousands of hectares of apples, it is tough to change practices unless forced upon you. (lack of honey bees for example.)
Small education. In the bee world,
-30% are social and build hives in the air (honey bees, paper wasps, etc.)
-40% are ground dwellers and are social or solitary (bumble bees, miner bees)
-30% are cavity nesters and typically solitary (blue orchard, rufas, cornifrons, aglaia)
A cavity nester uses their hole for nesting. They gather pollen, lay an egg, and then seal this egg chamber with mud/resin/leafs/masticated vegetation/pebbles. The bee lives about 4-6 weeks before the season for this species to be complete. The egg hatches, the larva eats the pollen, spins a cocoon and metamorphosus into an adult bee. The bee then emerges from that hole in time for the next season. ...in other words, each hole is used for an entire year-long life cycle.
The mason bees that I'm using/encouraging are the Blue Orchard & Hornfaced that use 8mm holes plus or minus. Another species that i'm encouraging for berries is Osmia aglaia that uses 5-6mm holes. I haven't progressed
enough to know quite yet which bee lives where and what their requirements are yet elsewhere in North America.
Your questions answered: What is the long term result if you put in many different sizes of material ? different sizes will attract different species at different times of the year. ...if they are available.
Is there a sequence of nesting insects, like a crop rotation ? Each location/region is different, but yes, we have orchard/berry/melon season bees of various species. Around the pacific northwest in the US, the spring bee is the blue orchard, followed by the aglaia, followed by "I don't know yet" for the melon (July/August) season.
Can a straw be "cleaned" for a bee by another insect ? No. each bee has their own unique scent which the others ignore. Each hole is used by one species for the entire year.
What if you dispersed small(er) hotels on the acreage you've got ? Would that relieve the pressure ? In a monoculter, or even 3-4 crop policulture, we are dispersing the shelters to a variable 20m spacing. depending on the crop, we have maybe 100 nesting females per shelter. In a natural environment, you might have 2-3 females/shelter, if that.
Realize that we have just 2-3 weeks of blossoms for this crop. With thousands of trees, we need a mass of bees available all at one time. When the crop is complete, this monoculture is a sahara desert to other native insects unless we encourage the farmer to plant/maintain hedges or between row plants. At a cost in both labor and material to the farmer. The honey bee is wonderful because the farmer just calls for bees to be dropped off and then picked up later.
With cavity nesters like the blue orchard mason bee, we can pick up the straw with the eggs in it and take them off site so that other predators (parasitic wasps, woodpeckers, bears, etc.) can't forage on the bees.
Would you be finding different species in different areas, with different neighbours and pests ? in an
organic farm, potentially yes. In a monoculture environment, few other species. But yes, each species will have their own pests/diseases/virus that they're susceptable to. Some pests/virus/diseases prey on multiple species. though in general, the varoa mite doesn't impact the blue orchard as an example.
Is there a hedge/compost heap/dry stone wall/brush pile equivalent for those bees - a large structure you can just set up to create a permanent environment ? this was a good Paul debate we had while sitting in my living room... Monoculture is a practice that right or wrong, is the major practice across the world. I know that in the UK, hedge rows are being forced(?) upon farmers as a good practice. In north america, it will be like extremely tough to force/encourage. Each farmer has only one set of equipment, ladders, sprayers, that they use. For them to try to be competitive on their product, this is must. It doesn't make it right, but in the free market society, it makes sense that it is what it is.
for a farmer to pull back 10-25% of their field to encourage native pollinators is a tough
sell. This
land, in many situations, would be bare unless the farmer used
energy to
water it. ...and as I type this, I know from Paul that there are better methods. But limited farmer knowledge.
I don't mean to create obstacles with all of the above argument. Rather, I am dealing with the food supply across north america with all sorts of farming practices. This is reality, right or wrong. It is this practice that for now, I have to work with. If there are better methods of farming that
permaculture can demonstrate, that must come from others... I can't educate the world. For now, my focus is obtaining alternate means of pollination.
John Polk... perhaps "stewardship" is a better word than "ownership." In either case, if I alter nature's natural cycle by proving food/lodging, i should continue to support them if I benefit from their presence.