Abstract: Beans and Mexican Bean Beetle

Small Group Session

Biological Control of the Mexican Bean Beetle: From the Farm to the Garden

Carol Holko, an entomologist from Maryland, described the efforts of the Maryland Department of Agriculture to explore the use of Pediobius foveolatus, a parasitic wasp attacking Mexican bean beetle (Epilachna varivestis) larvae, in small farms and gardens growing snap beans. This wasp has been successfully used against the Mexican bean beetle in soybeans for many years, and the Maryland Department of Agriculture maintains stock colonies of this parasitoid because it does not overwinter.

Experiments with Using a Parasitic Wasp for Biological Control of Mexican Bean Beetle on Snap Beans

Kim Stoner, an entomologist from Connecticut, described her experiments using P. foveolatus against Mexican bean beetle at organic farms and community gardens. Results have been mixed so far.

Discussion: Beans and Mexican Bean Beetle

Kim Stoner presented more detailed results during the discussion period. At each of the organic farms, she made two releases of P. foveolatus wasps, first when adults and egg masses were found, and the second a week later. The first generation of mummies (bodies of parasitized Mexican bean beetle larvae) appeared in mid-July in low densities. By this time, the first generation of Mexican bean beetle larvae had already done significant damage. At some sites, there was enough parasitism to prevent the Mexican bean beetle larvae from pupating in large numbers, few new adults emerged, and damage from the second generation of larvae was insignificant. In other sites, the build-up of parasites did not prevent pupation and emergence of new adults. Although the second generation of larvae were controlled by the parasite, this was late in the season.

There was also discussion about what farmers might do to create a better habitat for P. foveolatus, and about the economics of biological control