Spirit Barrier / Spirit Zapper, defends against spirit powers? Options

[Bearclaw]

Hi, I recently came across something I hadn't noticed before and just wanted to double check.
Spirit Barrier clearly says it defends against spirit powers. Is this correct?
I'd always worked under the assumption that NOTHING worked against spirit powers, but:
SM pg 174
This modified version of the Mana barrier spell (p. 204, SR4) only works against spirits and spirit powers.

That's pretty clear. And also implies that Mana Barrier works against spirit powers. Am I missing something, or have I just always been wrong that there wasn't much you could do about spirit powers?

[Mantis]

Here is a bit from pg 204 SR4A that adds some detail to this. This is from the Mana Barrier section.

Adept powers and many always-on critter powers are innate and
so are unaffected by a barrier, though if the gamemaster chooses certain
ranged and sustained critter powers (such as Concealment or
Movement) may suffer the same fate as spells or foci (using the critter’s
Magic rather than Force).

So by GM choice, spirit powers could be affected by mana barriers.

The spell Spirit Barrier is very explicit in that it does affect spirit powers. So yeah, there is at least one spell that impedes spirit powers.

[Bearclaw]

I'll probably take the spirit-zapper. It looks like we'll be dealing with more bug spirits, and that would really help.
A sustained force 9 bug-zapper would really mess up their day.