I'm curious if anyone has tried these for fungas gnat control or any other sort of subterranian pest to fig trees and their cuttings?  They are a bit on the expensive side, but with all we put into our fig tree hobby they may be worth it.  I know some members swear by using BT for fungus gnat control. 

I have been playing with the idea of using them in my garden for years to thwart the tiny SOB's that chew holes in my carrots, but discovered if I planted onions and garlic adjacent to them it pretty muched stopped the problem and cost me nothing. But still, they have a shelf life of 6 months and if they could pull double duty for figs and garden pests like cabbage loopers and tiny carrot chewing SOB's...the price may be justified.

Oop, I found a different source that says they need to be used within 2 weeks. So much for the double duty. The question still remains, have you or anyone you know tried them? Navid mentioned using them in an old thread about Japanese beetles, but no further information. Also, the variety you use for Japanese beetles is different than one would use for fungus gnats.

You can get BT in a dried form and then mix it with water as you need it, I have used it on a commercial level when it was 1-2 years old (stored in a cool dry place) and it worked just as well as the new stock.  There are different species of bacillus that will work for different things, some for fungi

Bacillus thuringiensis subspecies israelensis is the one in Vectobac which is used for fungus gnats but just because you can't find the israelensis sub species doesn't mean that the BT you find won't work, the sub species just does a better job on the fungus gnats than the other but it will still work, you might have to do a couple applications but it still will work.

If you have a nematodes problem, the best thing is mulch or  manure or both. You will enrich the soil and nematodes stay away because they do not like it!
Not counting the enriched soil and moisture retention: you win both ways!
Sal