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United States Department of Agriculture

Agricultural Research Service

Research Project: PROACTIVE MANAGEMENT FOR SUSTAINABLE RANGELAND PRODUCTION

Location: Livestock and Range Research Laboratory (LARRL)

Title: Short-Term population dynamics and impacts of the red-headed leafy spurge stem borer (Oberea erythrocephala (Schrank.) Coleoptera: Cerambycidae) on leafy spurge (Euphorbia esula)

Authors
item Progar, R -
item Markin, G -
item Milan, J -
item Barbouletos, T -
item Rinella, Matthew

Submitted to: Invasive Plant Science and Management
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: September 19, 2010
Publication Date: April 1, 2011
Citation: Progar, R.A., Markin, G., Milan, J., Barbouletos, T., Rinella, M.J. 2011. Short-Term population dynamics and impacts of the red-headed leafy spurge stem borer (Oberea erythrocephala (Schrank.) Coleoptera: Cerambycidae) on leafy spurge (Euphorbia esula). Journal of Invasive Plant Science and Management. 4(2):183-188.

Interpretive Summary: We studied the efficacy of a biological control agent, the red-headed leafy spurge stem borer against the invasive weed leafy spurge. We used three treatments in triplicate at six sites in the Western U.S. These treatments were release of the stem borer into caged and uncaged plots and no release of the stem borer into caged control plots. We measured leafy spurge biomass for one year following release and we also measured the percentage of leafy spurge stems showing evidence of stem borer egg deposits. The red-headed leafy spurge stem borer did not significantly reduce leafy spurge biomass and when compared to the release year, evidence of stem borer egg deposits decreased after the release year suggesting the stem borer population was diminishing. This suggests the agent is incapable of building large populations for controlling leafy spurge at the sites we studied. However, after being released, populations of biological control agents sometimes go through long lag phases and then begin rapid population growth, so we cannot completely rule out the possibility that the red-headed leafy spurge stem borer might become effective against leafy spurge given more time.

Technical Abstract: We researched the efficacy of the biological control agent Oberea erythrocephala against the nonnative invasive plant leafy spurge (Euphorbia esula). Our three treatments were release of O. erythrocephala into uncaged plots, release of O. erythrocephala into plots caged to prevent agent escape and control plots caged to prevent agent entry. These treatments were replicated three times at six sites in the western U.S. We measured E. esula biomass for one year following release. We also measured the percentage of E. esula stems showing evidence of O. erythrocephala oviposition for either two or three years following agent release, depending on the site. O. erythrocephala did not demonstrably reduce E. esula biomass in our study. Moreover, compared to the release year, evidence of O. erythrocephala oviposition was much lower after the release year suggesting the agent population was diminishing. This suggests the agent is incapable of building large populations capable of controlling E. esula at the sites we studied. However, after being released, populations of biological control agents sometimes go through long lag phases and then begin rapid population growth, so we cannot completely rule out the possibility that O. erythrocephala might become effective given more time.

Last Modified: 7/25/2014
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