Just a quick tidbit of interesting info to share…
A recent reader question about predatory nematodes (and their usefulness in a worm bin) reminded me of the fact that I came across an interesting scientific journal article that discussed interactions between Eisenia fetida (our good friend the Red Worm) and Steinernema feltiae.
You may recall that I was quite pleased with the initial effectiveness of S. feltiae against a serious population of fungus gnats that had developed in my vermicomposting systems (see Steinernema feltiae – Fungus Gnat Killer). I also tested them against fruit flies (see Steinernema feltiae VS The Fruit Flies), but didn’t end up with any conclusive results unfortunately.
One of the things I wondered about in the case of adding the nematodes to a worm bin is the potential competition/predation from the bin inhabitants, including the Red Worms themselves. A composting system tends to have a much more diverse ecosystem than that found in regular soil or inert growing media – where these nematodes are usually applied. Undoubtedly the sheer numbers of the nematodes being added certainly helps to explain their initial effectiveness, but it seemed as though something was decreasing their overall potency over time (although, that being said, I should mention that I have not had a really bad infestation since then).
This article (see reference section below for more info) seems to support one of the hunches I had – that Red Worms do indeed kill off nematodes via passage through their digestive system. The researchers were actually wondering if earthworms could improve the effectiveness of the nematodes by helping to disperse them, but found that the opposite was true. The digestive enzymes of E. fetida are simply too potent to allow safe passage of the nematodes through their gut.
Definitely something to think about, especially if your vermicomposting systems have high worm densities (although, with high enough worm densities the threat of serious gnat/fruit fly invasions will be greatly reduced).
Campos-Herrera, R., Trigo, D., and C. Gutiérrez. 2006. Phoresy of the entomopathogenic nematode Steinernema feltiae by the earthworm Eisenia fetida. Journal of Invertebrate Pathology, 92: 52-54.**Want Even More Fun With Worms? Sign Up for the RWC E-mail List Today!**
Aww, I was hoping S. feltiae could coexist with E. fetida. Guess not. Man, those redworms are voracious, aren’t they? 😉 Wonder how Heterorhabditis bacteriophora fares in its gut? I’d disperse some of those just to see pests die and glow >=D
Is there a way to culture the nematodes separately… like you do redworms…
Have you tried culturing them… since..
I’m sure there IS an effective way to culture them (since presumably that’s how they are produced by bio-control companies in such large numbers), but I’m not really sure. I seemed to have SOME success using host organisms (fruit fly larvae etc), but it wasn’t foolproof.
The nematodes live on meat like products, I discussed this with a microbiologist friend, they grow them in what they call a “recipe” of some meat product like dogfood cooked with agar. The scientific literature also has some recipes discussed (which I have not looked at). The nematodes will not live of stuff like the redworms would eat.. eg decaying veggie/cellulose stiff..
I have wireworms and cut worms in my garden. I also have red worms living there naturally. Will the nematodes I need to apply to my garden fall victim to the redworms or will they escape and do their job? I have two 20 x 48 gardens so my hope is the nematodes will survive because of the size.