Beneficial Nematodes
by: Allen Buchinski
In my previous article, I discussed "what are nematodes" with a focus on plant parasitic types. Here we'll focus on the beneficial kind.
As you surely remember, nematodes are tiny round worms that proliferate in nature. Of all nematodes, only a portion cause problems in your garden, these types live on or in plant tissue, disrupting the plant's natural processes. There are many other nematodes that feed on other things, including organic matter in the soil, bacteria, insects, even animals. It's the insect eating variety that's of interest to us here, harnessing them to help us with insect pests in the garden.
How Do They Work?
Since nematodes live in the soil, they can be used against insects that spend at least part of their lifecycle underground, typically the larvae form (although researchers are also exploring the methods for applying nematodes above ground as well by timing the release in such a way that they can enter a host insect before succumbing to the elements.) There are two strategies used by nematodes for finding prey, depending on the species:
One type, called "ambusher", remains stationary in the ground, waiting for an insect to pass by,
The other, labeled "cruiser", travel through the soil in search of prey, using techniques including following excrement trails and reacting to changes in temperature and carbon dioxide levels.
In order for nematodes to be available commercially, they must be able to be mass produced and shown to be effective against insect pests. Currently, there are about five varieties produced for sale, grown for use against root weevils (including the black vine weevil), cutwowrms, fleas, ants, termites, grubs and more. They're available from many garden suppliers and can be purchased by mail order.
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