We're obviously looking at how egg cells (and possibly sperm cells) are made.
My understanding is that these RNP particles move into the oocyte along with other other components that are being transferred from the nurse cells.
You might have to look up gametogenesis to get a better feel for the process.
The RNP then makes it to the nucleus (possibly via the cytoskeleton) where it then reverse transcribes and integrates into the host genome.
So, the transposable element makes it to the nucleus during gamete formation and integrates.
After that, it's resistance via RNAi, as in the Maori paper.
This is the only example of Honeybee disease resistance by evolution, that I am aware of, that is so well documented.
I don't think that we can say the same for any of the other possible mechanisms being discussed. That's what makes it special.
Out of 8 splits from an obviously DWV infected hive (there was a funnel of dead bees, with shriveled wings, leading back to the hive), 1 was good enough to rehive.
Even though we're going to take a look for evidence for DWV integration, it might take a while before we actually know if the new hive is truly resistant.
Hunting for jumping genes is never an easy task.