Leafy spurge, Euphorbia esula L., has become a wide spread weed in North Dakota. Starting in 1988, we studied the population development of Aphthona spp. as biological control agents of leafy spurge and measured the change in the spurge plant variables across a diversity of spurge infested habitats in North Dakota. To determine the flea beetle population development at each site, sweep net samples were taken weekly each year when adults were present. Soil cores were collected each fall to measure the spurge root systems. Above-ground mean leafy spurge stem density was derived from 1-m2 random samples taken each year. Aphthona lacertosa established at sites ranging from high and dry to cooler and moister habitats with shade and denser stands of spurge, with silt loam, silt clay loam, clay loam, loam, or sand loam soil conditions. Leafy spurge stem and root tissues decreased an average of 70 to 90% under these conditions. In areas with well drained loam soil and spurge densities of 146-229 stems/m2, Aphthona nigriscutis populations developed to 400-700 adults/m2 within three years after their release, and the leafy spurge infestation decreased by an average of 90% within seven years after the initial release. Habitats where A. flava persisted had silt clay loam soil, and a leafy spurge density of 145-371 stems/m2. Aphthona lacertosa appears to have a wide habitat range in North Dakota, and therefore this species would appear to be effective against spurge in several of the habitats that occur across North Dakota.
Species 1: Coleoptera Chrysomelidae Aphthona lacertosa (Flea beetle)
Species 2: Coleoptera Chrysomelidae Aphthona nigriscutis (Flea beetle)
Species 3: Coleoptera Chrysomelidae Aphthona flava (flea beetle)
Keywords: Leafy spurge, biological control
Back to Ten-Minute Papers, Section Cc. Insect Vectors in Relation to Plant Disease, Ce. Insect Pathology and Microbial Control, Ca. Biological Control
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