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Poster

10. Biocontrol of Leafy Spurge with Aphthona Nigriscutis in Alberta "The Beverly Bridge Site."  K. Stromme and D.E. Cole, Alberta Agriculture and Rural Development, Agronomy Unit Edmonton, Alberta, A.S. McClay, Alberta Environmental Centre, Vegreville, Alberta; C.J.Richardson and J. de Valois, Alberta Agriculture, Food and Rural Development, Public Land Services, Sherwood Park, Alberta.

There are over 130 research sites in Alberta where Aphthona nigriscutis beetles have been released on leafy spurge. Once beetles have established, the population is monitored and vegetation data is collected from the sites. A. nigriscutis, the black dot spurge beetle, is most effective on lighter soils with leafy spurge flowering heights of less than 70 cm, and on high, dry slopes or hilltops.

The Beverly Bridge in Edmonton is one of the most successful A. nigriscutis sites in Alberta. In 1989, 500 beetles were released at one of six sites on the Beverly bridge. The site is located on a dry, south facing railway embankment. The soil texture is 82% sand, 14% silt and 4% clay. The leafy spurge was very dense at 279 shoots/m2, and the above ground leafy spurge biomass at the time of the release was over 170 g/m2. The flowering leafy spurge canopy was 60 cm in height.

In 1992, the beetle population peaked, and by 1993 the leafy spurge biomass was reduced to less than 2 g/m2, while the grass biomass increased to 43 g/m2. The leafy spurge density and percent cover were also dramatically reduced after four years time.

Year Leafy Spurge% cover Leafy Spurge Shoots/m Leafy Spurge Biomass g/m2 Grass Biomass g/m2
40 279 172.61.4
25 395 140.1 18.9
6.6109 26.7 14.1
1 8 1.6 42.9
1.5 8 2.2 57.1
1.7 5 1.7 43.3
Beverly Bridge Site # AB-89-0015

There have been over 100,000 beetles collected and redistributed from this site.

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