Biological control of leafy spurge with introduced flea beetles (Aphthona spp.)

Flea beetles (Aphthona spp.) were introduced into leafy spurge (Euphorbia esula L.)-infested rangeland in east-central North Dakota. The study objectives were to evaluate the effects of the introduced insects on leafy spurge cover, density, and yield, and grass and grass-like yield of associated plant communities. Aphthona spp. were released in 1988 and 1989 at 2 sites near Valley City, N.D. Aboveground vegetative sampling for leafy spurge cover, density and yield, and grass and grass-like yield was conducted between 1993 and 1995. Belowground sampling of root density, dry weight and root buds was conducted between the release date and 1995. Aphthona spp. reduced aboveground cover, density and yield of leafy spurge and increased yield of grass and grass-like species. Leafy spurge root density, weight, and number of root buds decreased on insect release sites between release dates and 1995. Reduced stem density of leafy spurge and increased grass and grass-like yield, should enhance cattle use and production from these sites.