Density and efficacy of the flea beetle Aphthona Lacertosa (Rosenhauer), an introduced biocontrol agent for leafy spurge, in Alberta

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Kalischuk, Andrea Ruth
University of Lethbridge. Faculty of Arts and Science
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Lethbridge, Alta. : University of Lethbridge, Faculty of Arts and Science, 2001
Biocontrol has been critized because the target effects of biocontrol introductions have not been studied rigorously. The objectives of this thesis were 1)to assess quantitatively the efficacy of a classical biocontrol agent after its release and 2)to suggest factors that affect the density and distribution of the biocontrol agent. In 1997, Aphthona lacertosa, a root-feeding flea beetle that is native to Europe, was released for the biological control of leafy spurge in Alberta. The beetles had established at more than 75% of the release sites that were monitored in 1999. In 2000, the peak abundance of A.lacertosa across release sites ranged from low (<10 beetles m-2) to high (>70 beetles m-2). Sites with high beetle densities had a significantly greater local (ie. within 5m of release point) reduction of leafy spurge than sites with low beetle densities. The density and distribution of A. lacertosa are affected by cumulative degree-days (CDD) at the release site and plant lacertosa are affected by cumulative degree-days (CDD) at the release site and plant morphology, respectively. Beetle population growth may be enhanced by releasing A. lacertosa at sites where there are more CDD. It is expected that high densities of A. lacertosa will effectively control leafy spurge populations.
93 leaves : ill. (some col.) ; 29 cm.
Flea beetles , Leafy spurge -- Control , Weeds -- Control , Dissertations, Academic