I posted this previously, and looks like a couple people were able to quote it before I made changes, but I edited it and added some info. 
The Accelerant and the Neomorphs, including the Deacon are indeed parasitic, but that doesn't mean they're self-sustaining. They may lack a reproduction cycle or a means to continue propagation of the species.
Black goo > Holloway > Mutated Sperm/Trilobite > Deacon > End
Black goo > Fungi > Mutated spore > Neomorph > End
Remember, the black goo was essentially a bomb that was supposed to wipe out civilizations to allow for a clean slate. It breaks down cells and essentially disintegrates the body of a mammal. I think it also depends on how it's applied - ingested, inhaled, skin contact, whatever have you. In the case of Fifield, the pure Accelerant is inhaled, but not enough to break down his body. Instead it mutated him and made him hyper-aggressive, a trait the Aliens seem to have through and through.
I have a feeling there's some sort of unintended side effect of the Accelerant, though. It can directly effect the reproductive systems of mammals it comes into contact with. Fungi are not plants. They are not flora. This is why the Accelerant has an effect on the Fungi and it's spores, and not plant life.
In the case of the worms, they were submerged in the Accelerant. But what ability do worms inherently possess? A worm can live as two separate entities and continue to live after they been cut in half - that's a form of reproduction.
The addition of the parasitic wasp may have been included, not for it's parasitic properties because that's already there, but for it's refined reproduction capabilities, and formidability, giving it an armored exoskeleton.
