Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: March 15, 2005
Publication Date: April 5, 2005
Citation: Slotta, T.A., Horvath, D.P., Foley, M.E. 2005. Genetic variability for biological control of Canada thistle. [Abstract]. Invasive Species Workshop. Page No. 47.
Canada thistle (Cirsium arvense) poses a threat to farmland and native plant communities by establishing persistent populations through a large number of wind-dispersed seeds and the development of an extensive root system. Attempts to control Canada thistle by introducing non-native weevils were effective, but native rare thistles were also attacked. These native thistles are closely related to Canada thistle, share habitat requirements, and may be better hosts for the weevils than the intended target. To avoid similar problems in the future, it is important to determine how closely related Canada thistle is to other thistles. Also, it is important to learn if different populations of Canada thistle across the region are similar enough so that an agent would work in many locations. We are looking at the DNA of Canada thistle and related species to determine the level of similarity within and between populations and species. From his information, we can examine: (a) the level of genetic variability present within Canada thistle populations, (b) how the populations are related to one another (variation between populations), (c) the relationship of Canada thistle to other thistles (variation between species), and (d) if breeding between Canada thistle and native thistles has occurred. In studying the distribution and genetic variation of Canada thistle, we should be able to predict which biological control agent will have an effect and how long any given control measure will remain effective before resistant populations begin to appear. To date, over one thousand plants in thirty populations of Canada thistle have been collected throughout North Dakota. Genetic variability of Canada thistle in North Dakota appears to be lower than that of native populations in Europe.