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Keyword: spotted knapweed

Population-level compensation impedes biological control of an invasive forb and indirect release of a native grass

Publications Posted on: May 30, 2012
The intentional introduction of specialist insect herbivores for biological control of exotic weeds provides ideal but understudied systems for evaluating important ecological concepts related to top-down control, plant compensatory responses, indirect effects, and the influence of environmental context on these processes.

Factors influencing plant invasiveness

Publications Posted on: December 02, 2009
Invasiveness of spotted knapweed and biological control agents. Dean and Yvette are examining the influence of drought on the invasiveness of spotted knapweed (Centaurea maculosa) and its susceptibility to herbivory by biological control agents. In collaboration with the University of Montana and Forest Health Protection, researchers have constructed 150 experimental plots.

Comparison of ground beetle (Coleoptera: Carabidae) assemblages in Rocky Mountain savannas invaded and un-invaded by an exotic forb, spotted knapweed

Publications Posted on: November 30, 2009
We compared ground beetle (Carabidae) assemblages between spotted knapweed (Centaurea maculosa Lam.) -invaded (invaded) and un-invaded (native) habitats in Rocky Mountain savannas. Carabids play important roles in biotic communities and are known as a good indictor group of environmental change.

Understanding the side effects of classical biological control

Publications Posted on: November 30, 2009
Classical biological control involves the use of imported natural enemies to suppress or control populations of the target pest species below an economically or ecologically relevant threshold. Biological control is a useful tool for mitigating the impacts of exotic invasive plants; however, its application is not without risk (see Carruthers and D’Antonio 2005, and articles contained in this special issue).

Root exudate is allelopathic in invaded community but not in native community: Field evidence for the novel weapons hypothesis

Publications Posted on: November 12, 2009
Invasion by exotic species threatens natural ecosystems (Wilcove et al. 1998) and has severe economic ramifications (Pimentel et al. 2000). In many cases, exotic species that form near monocultures in their invaded range are much rarer in their native communities (Lonsdale & Segura 1987; Braithwaite et al. 1989; Malecki et al. 1993; Eckert et al. 1996; Meyer & Florence 1996; Bruce et al. 1997; Paynter et al. 1998; Memmott et al.

An indirect dispersal pathway for spotted knapweed seeds via deer mice and great-horned owls

Publications Posted on: October 22, 2008
Spotted Knapweed (Centaurea maculosa) seeds were found in the pellets of Great Horned Owls (Bubo virginianus). That apparently resulted from owls preying upon Deer Mice (Peromyscus maniculatus) which had incidentally consumed knapweed seeds while foraging for the larvae of biological control agents within knapweed seedheads.

Deer mouse predation on the biological control agent, Urophora spp., introduced to control spotted knapweed

Publications Posted on: September 25, 2008
Field observations made in 1993 suggested that rodents were preying on spotted knapweed (Centaurea maculosa) seedheads, possibly targeting the gall fly larvae (Urophora spp.) which overwinter within them. I conducted a brief study to determine the cause of seedhead predation and quantify gall fly predation. Stomachs were examined from 19 deer mice (Peromyscus maniculatus) captured in the fall of 1993 and winter of 1997.

Mitigating exotic impacts: restoring native deer mouse populations elevated by an exotic food subsidy

Publications Posted on: September 02, 2008
The threat posed by exotic organisms to native systems has led to extensive research on exotic invaders, yet management of invasives has progressed relatively slowly. This is partly due to poor understanding of how exotic species management influences native organisms.

Insect herbivory stimulates allelopathic exudation by an invasive plant and the suppression of natives

Publications Posted on: June 21, 2006
Exotic invasive plants are often subjected to attack from imported insects as a method of biological control. A fundamental, but rarely explicitly tested, assumption of biological control is that damaged plants are less fit and compete poorly.