As readers may recall, I ended up with a VERY serious infestation of fungus gnats in this system not too long ago (see “Worm Inn Journal-12-02-11“), and added a lot of parasitic nematodes in an effort to see if I could get things under control.
Initially, I was planning to do some serious gnat-vacuuming as well (taking advantage of the fact that fungus gnats are very attracted to lights) – but then decided against it on the recommendation of one of our readers. As this person pointed out, waiting to see how effective the nematodes were on their own might be a better approach.
I’m glad I did! (Thanks again, Richard!)
While I certainly won’t claim that all the fungus gnats have vanished, I am definitely blown away by the drastic reduction in the population of adults in the system (which seems to indicate that many larvae have been killed by the nematodes). Had I started vacuuming up adults like a madman, it would have been a lot harder to determine if the nematodes were having a significant impact or not.
I can’t say for sure – but I have a sneaking suspicion that these nematodes (Steinernema feltiae) are more effective against fungus gnats than against fruit flies – which I guess shouldn’t be too surprising since gnats seem to be the main target organisms they are used for. There is no doubt that S. feltiae CAN and DO kill the fruit fly larvae – as I’ve seen in my little fruit fly farms – but I haven’t seen the same sort of impact on the adult population (something I’m very puzzled by, to be honest). I think what I really need to do – apart from more testing with fruit flies – is see if I can set up an experimental “gnat farm” as well, so I can see (up close and personal) how the nematodes are affecting the overall population.
Anyway – based on this positive progress on the gnat-eradication front, I may start adding more food to the Worm Inn fairly soon. I’m certainly not going to wait until every last gnat has vanished from the system.
Will keep everyone posted