Nursery, Greenhouse, and Landscape

Slugs R Us: Research Project May Provide Biological Control

In the February 1998 edition of MBCN, we briefly reported on the nematode Phasmarhabditis hermaphrodita, which is a parasite of true slugs. A UK company, MicroBio, is commercially producing the nematode and marketing it for biological control through much of the United Kingdom and Europe. In field trials in Switzerland, it was equally effective as metaldehyde, the standard chemical slug control sold as a bait formulation. Although MicroBio has an interest in marketing the nematode here in the U.S., it isn't known to occur here naturally and there are concerns in the regulatory community about introducing a non-native species. MicroBio scientists believe that P. hermaphrodita may very well already occur in North America, but it just has yet to be documented. If it does occur naturally here, it would be much easier to satisfy the requirements for product registration in the U.S. Therefore, a research project is underway to survey for the presence of the nematode.

Slugs are being collected in the states of Oregon, Michigan, Ohio, Wisconsin, and Maryland, and the Canadian provinces of British Columbia and Ontario. The live slugs, collected by the hundreds, are being shipped to the lab of Dr. Parwinder Grewal at Ohio State University, where they are being evaluated for the presence of P. hermaphrodita.

Here in Wisconsin we are involving the university's Extension Master Gardener program in the survey. Five county-based Master Gardener programs are independently coordinating collection and shipping of slugs directly to Dr. Grewal's lab for analysis. The slugs are packaged and labeled based upon specific collection locale and date, and provided food while in shipment to Ohio via Federal Express. In exchange for their labors, MicroBio is providing each of the Master Gardener groups with a small honorarium to use in their programs. Additionally, the cooperating Master Gardeners receive experience in conducting a research project, and may eventually benefit if an effective slug biological control product becomes available for use here in the U.S. Should this occur, information on its availability and proper use will be developed for use by Master Gardeners as they conduct their Extension educational programs.

- Dan Mahr, University of Wisconsin - Madison

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