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Effects of a non-native biocontrol weevil, Larinus planus, and other emerging threats on populations of the federally threatened Pitcher's thistle, Cirsium pitcheri

Biological Conservation

By:
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DOI: 10.1016/j.biocon.2012.06.010

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Abstract

Larinus planus Frabicius (Curculionidae), is a seed-eating weevil that was inadvertently introduced into the US and was subsequently distributed in the US and Canada for the control of noxious thistle species of rangelands. It has been detected recently in the federally threatened Pitcher's thistle (Cirsium pitcheri). We assayed weevil damage in a natural population of Pitcher's thistle at Whitefish Dunes State Park, Door County, WI and quantified the impact on fecundity. We then estimated the impact of this introduced weevil and other emerging threats on two natural, uninvaded populations of Pitcher's thistle for which we have long-term demographic data for 16 yr (Wilderness State Park, Emmet County, MI) and 23 yr (Miller High Dunes, Indiana Dunes National Lakeshore, Porter County, IN). We used transition matrices to determine growth rates and project the potential effects of weevil damage, inbreeding, goldfinch predation, and vegetative succession on Pitcher's thistle population viability. Based on our models, weevil seed predation reduced population growth rate by 10–12%, but this reduction was enough to reduce time to extinction from 24 yr to 13 yr and 8 yr to 5 yr in the MI and IN population, respectively. This impact is particularly severe, given most populations of Pitcher's thistle throughout its range hover near or below replacement. This is the first report of unanticipated ecological impacts from a biocontrol agent on natural populations of Cirsium pitcheri.

Additional Publication Details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
Effects of a non-native biocontrol weevil, Larinus planus, and other emerging threats on populations of the federally threatened Pitcher's thistle, Cirsium pitcheri
Series title:
Biological Conservation
DOI:
10.1016/j.biocon.2012.06.010
Issue:
155
Year Published:
2012
Language:
English
Publisher:
Elsevier
Publisher location:
Amsterdam, Netherlands
Contributing office(s):
Western Ecological Research Center
Description:
10 p.
Larger Work Type:
Article
Larger Work Subtype:
Journal Article
Larger Work Title:
Biological Conservation
First page:
202
Last page:
211
Country:
United States