The key element so far as I've seen appears to be detergent, which suggests that the critical element is probably something that breaks down fatty acids.

I'm suspecting this either breaks down critical messaging / management chemistry, or carapace / cell-wall functions. I've had little luck determining or finding what the specific lethal mechanism is, though the method appears effective.

Upshot: a non-sudsing detergent or other fatty-acid denaturing agent should likely work. Formula 409 might work, ammonia is another possibility, though that in a shop-vac will have its own atmospheric issues (though the smell should dissipate in a well-ventilated area).