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United States Department of Agriculture

Agricultural Research Service

Research Project: BIOLOGY AND MANAGEMENT OF INVASIVE WEEDS IN THE WESTERN UNITED STATES Title: Cause and Effect, and How to Make a Better Biocontrol Agent

item Smith, Lincoln

Submitted to: Biocontrol News and Information
Publication Type: Other
Publication Acceptance Date: May 3, 2006
Publication Date: June 12, 2006
Citation: Smith, L. 2006. Cause and effect, and how to make a better biocontrol agent. Biocontrol News and Information.27(2):28N-30N.

Technical Abstract: Pearson and Callaway (2006) published data supporting the theory that a host-specific insect biological control agent of spotted knapweed is providing food for deer mice, increasing their population and the abundance of a hantavirus they harbor. This virus can infect people causing hantavirus pulmonary syndrome (HPS). They argue that ineffective biological control agents can cause indirect nontarget effects, including risk to human health. My article is a response to this paper. I point out that an error in their choice of which data to analyze invalidates their conclusion that it was insect, rather than knapweed, abundance that caused mouse populations to increase. I explain that rodent predation of the biological control insects can reduce their populations and reduce their effectiveness. They argue that efficacy of biological control agents is important to help minimize nontarget effects. However, they do not appear to be aware that practitioners of biological control have long recognized the importance of efficacy in selecting agents for introduction. Classical biological control is still the most effective method to achieve long-lasting control of an invasive weed over large areas with minimal environmental impacts.

Last Modified: 4/21/2015
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