You Are Here: Management Updates 2000 Archive June 9, 2000

Date: June 9, 2000
Category: Nematodes
Subject: Biological Control of Nematodes

We usually think of biological control as a commercialized product, however, biological control is also a natural process that is especially active in soil. Nematodes, like other life forms are subject to a variety of pathogens. Fungi, bacteria, and predacious nematodes commonly attack nematodes.

At the Plant Disease Diagnostic Lab at the University of Massachusetts we are examining nematodes from turf grasses for the presence of Pasteuria. Pasteuria is a bacterium that attacks nematodes and water fleas. It is believed to be very host specific so that Pasteuria that infects one species of nematode is a weak or non-pathogen of other species. The bacterium cannot be cultured in the laboratory so it is very difficult to work with. Pasteuria can be cultured on living nematodes but nematodes are also difficult to grow because they also need a living host.

Pasteuria is shaped like a hub cap on a car (Fig 1 & 2). The bacterium is very resistant and can survive in the soil for a year or more. When a nematode comes in contact with it, the bacterium sticks to the nematode. The bacterium then produces a hypha (like a fungus) which penetrates through the cuticle and into the nematode body. The hyphae then grow through the nematode and produces sporangia and endospores (Fig 3). When the nematode dies, the endospores are released into the soil. Nematodes may have multiple infections (Fig 4) but only one infection is necessary to result in a nematode full of endospores.

It may be decades before anyone will be able to develop a commercial product based on Pasteuria. However in a study carried out in Florida, root-knot nematode (Meloidogyne) populations nearly disappeared due to the natural build up of Pasteuria in the soil. Sting nematode (Belonolaimus) populations in Bermuda grass have also been suppressed by Pasteuria. We are finding that stunt nematode (Tylenchorhynchus) populations can have significant levels of infection. We are also finding Pasteuria on root-knot nematodes in turf. We are currently assessing the importance of Pasteuria in these populations.

Reference: Z. X. Chen and D. W. Dickson. 1998. Review of Pasteuria penetrans: biology, ecology, and biological control potential. Journal of Nematology 30:313-340.

- Submitted by: Dr. Rob Wick