Journal of Shellfish Research 12(1):147 (1993)

National Shellfisheries Association, Portland, Oregon

Abstracts, 1993 Annual Meeting, May 31-June 3, 1993

APPROACHES TO THE BIOLOGICAL CONTROL OF ZEBRA MUSSELS.

Daniel P. Molloy, Biological Survey, New York State Museum, Albany, NY 12230.

This paper examines what role biological control techniques may play in the integrated pest management of zebra mussels, Dreissena polymorpha.

Predators: Numerous organisms are known to prey on zebra mussels, but each would appear to be of little usefulness in actual control projects. Predators, however, have been reported to significantly reduce localized field populations of zebra mussels and could play an important role in the long-term reduction of zebra mussels in lakes, rivers, etc.

Parasites: Very little research has been conducted on zebra mussel parasites. A recent study in the Netherlands, however, has reported a severe and apparently lethal protozoan infection. Future use of parasites as biocontrol agents can not be dismissed. In terms of environmental impact, parasites are ideal control agents since they have been fine-tuned through evolution to be host specific and thus should cause negligible nontarget problems. Parasites, however, often have complex growth requirements and elaborate life cycles; these two characteristics can represent formidable obstacles toward economical mass production-a requirement for commercialization.

Toxin-Producing Microbes: A third and novel approach to developing a biological control method for zebra mussels is the screening of microorganisms (primarily bacteria) to find strains that are selectively lethal to these mussels. The microorganisms screened are not truly invasive parasites of zebra mussels, but rather microbes which are fortuitously lethal to zebra mussels when the mussels are exposed to artificially high densities of these microbes or their metabolic byproducts. Once a promising strain is found, these microbes can often be economically mass produced in vitro--a characteristic which can lead to their rapid commercialization. Such a screening process has a clear record of success in the development of microbial insecticides and may well prove valuable for zebra mussel control also. Laboratory data on lethality of bacterial stains will be presented.