Weevils to the rescue? Are biological control agents of musk thistle feeding on native thistle species in Tennessee?
Gregory J. Wiggins, firstname.lastname@example.org, Jerome Grant, email@example.com, and Paris L. Lambdin, firstname.lastname@example.org. University of Tennessee, Department of Entomology and Plant Pathology, Knoxville, TN
Two weevil species, the head weevil (Rhinocyllus conicus)and the rosette weevil (Trichosirocalus horridus) were released in the late 1980s and early 1990s in Tennessee as part of an IPM program to reduce populations of the invasive exotic musk thistle (Carduus nutans). The weevils have become established throughout eastern Tennessee in areas infested with musk thistle, reducing some musk thistle populations by as much as 90%. However, growing concern suggests that these species may shift or expand host ranges and feed on native thistle species. In spring of 2004, a preliminary survey was conducted to investigate the incidence of these two weevil species on field thistle (Cirsium discolor), as well as several other species of thistle. Field thistle, a native species in Tennessee, grows and flowers during the two-month interval of peak weevil activity. Ten plants from at least one site in each of ten counties were collected from the field, taken to the laboratory, and examined for herbivory by head and rosette weevils. Results from this preliminary study will be presented.
Species 1: Coleoptera Curculionidae Rhinocyllusconicus (head weevil) Species 2: Coleoptera Curculionidae Trichosirocalushorridus (rosette weevil) Keywords: biological control, non-target species