Is there rapid evolutionary response in introduced populations of tansy ragwort, Jacobaea vulgaris, when exposed to biological control?

AbstractQuantification of interference with biological control agents can provide support for anecdotal claims of success or failure of agent establishment and efficacy. This study was initiated because of observed predation of cinnabar moth larvae by carpenter ants when releasing larvae for the control of tansy ragwort, an invasive plant in Montana. Biotic and abiotic factors were compared among three sites with historically variable moth population establishment. Two experiments were developed to (1) observe and document insect activity, predation, or disappearance on tansy ragwort stems either protected or accessible to ants; and (2) quantify the effects of ant exclusion on herbivory of tansy ragwort. Site comparisons indicated that ant colony density was highest at the driest of three sites, and, interestingly, no ant colonies were detected at the site with higher observed numbers of moth larvae and adults and lower densities of tansy ragwort. Available substrate (logs and stumps) for ant colonization did not differ between the three sites. In the ant exclusion experiments, a larger number of larvae were missing on plants accessible to ants (63%) compared with plants where ants were excluded (39%) after 36 h. Direct observation of predation of larvae by carpenter ants accounted for 9% of missing larvae on stems accessible to ants. Larvae were able to consume 81% of original flowers or buds on ant-excluded stems, compared with 18% consumption on ant-accessible stems, suggesting that ant predation could limit the efficacy of cinnabar moth larvae. These results provide one of many possible explanations for the anecdotal observations of large, persistent populations of cinnabar moths in moist areas. This work emphasizes the importance of post-release observation and monitoring to detect and, ideally, quantify factors to support anecdotal perceptions regarding the fate and subsequent efficacy of insect biological-control agents.

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Longitarsus jacobaeae (Coleoptera: Chrysomelidae), a Flea Beetle for the Biological Control of Tansy Ragwort. 4. Life History and Adult Aestivation of an Italian Biotype2

Annals of the Entomological Society of America ◽

10.1093/aesa/66.2.358 ◽

1973 ◽

Vol 66 (2) ◽

pp. 358-367 ◽

Cited By ~ 11

Author(s):

Kenneth E. Frick ◽

Gerald R. Johnson

Keyword(s):

Biological Control ◽

Life History ◽

Flea Beetle ◽

Longitarsus Jacobaeae ◽

Tansy Ragwort

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DNA-Based Marker Systems to Determine Genetic Diversity of Weedy Species and Their Application to Biocontrol

Weed Science ◽

10.1017/s0043174500081546 ◽

1995 ◽

Vol 43 (3) ◽

pp. 504-513 ◽

Cited By ~ 54

Author(s):

Scott J. Nissen ◽

Robert A. Masters ◽

Donald J. Lee ◽

Martha L. Rowe

Keyword(s):

Genetic Diversity ◽

Biological Control ◽

Weed Control ◽

Random Amplified Polymorphic Dna ◽

Biological Weed Control ◽

Multiple Introductions ◽

Introduced Populations ◽

Length Polymorphisms ◽

Geographic Origins ◽

Weedy Species

DNA-based molecular markers may provide information about introduced weedy species that would be useful in biological weed control efforts. Chloroplast DNA restriction fragment length polymorphisms (cpDNA RFLP) and random amplified polymorphic DNA (RAPD) analysis are two DNA-based marker techniques that can provide estimates of genetic variation in native and introduced populations of weedy species. Profiles provided by these techniques could furnish the necessary information to determine the geographic origins of introduced species and provide evidence for multiple introductions. Although DNA-based markers would not necessarily identify the genetic basis for host-pest compatibility, they would enable identification of specific host genotypes. Current criteria for selecting a weedy species as a target for biological control are primarily political and economic. The importance of genetic diversity and population structure in determining the vulnerability of plant populations to insects or diseases has not been fully appreciated. Estimates of genetic diversity based on DNA marker analysis could be used as one criteria for determining which plants are targeted for biological control. The success of biological weed control efforts has been limited by the high levels of genetic diversity occurring in target weed specks and the lack of biocontrol agent and target weed compatibilities. DNA-based markers may be used to increase our understanding of these factors and contribute to the success of biological weed control by helping to target the most vulnerable species and provide more realistic expectations of the potential for success given available resources.

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