|Michels, Jr., Gerald|
|Ochoa, Ronald - Ron|
Submitted to: Entomological News
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/25/2008
Publication Date: 11/1/2008
Citation: Michels, Jr., G.J., Carney, V.A., Lydon, J., Ochoa, R., Renn, R.L. 2008. New records for Aceria anthocopes (Acari: Eriophyidae) occurring on Canada thistle in Colorado, Nebraska and Wyoming. Entomological News. 119:483-491. Interpretive Summary: While several biological control agents have been developed and released to control Canada thistle (Cirsium arvense), this invasive species continues to be a major pest in temporate regions of the U.S. To assess the use of the rust mite Aceria anthocoptes as a biological control for Canada thistle in mid-western states, a survey was conducted in eastern Colorado and Wyoming and western Nebraska to determine its current distribution in these areas. The mite was found to be present throughout the region, although not present in all sites included in the survey. Based on plant density measurements at one of the locations, a gradual decline and ultimate disappearance of Canada thistle over an eight year period may have been attributed to the presence of the mite. This study, which provides information on the current distribution of A. anthocoptes on Canada thistle, will be of value to biological control practitioners interested in controlling Canada thistle in agricultural and natural areas.
Technical Abstract: Thirty-two Canada thistle infestations in eastern Colorado and Wyoming and western Nebraska were surveyed in 2004 for the eriophyid mite Aceria anthocoptes (Nal.). Mites were abundant at 41% of the sites, present in lesser numbers at 53% of the sites, and no mites were found at 6% of the sites. In 2005, in addition to two new sites, ten of the sites sampled in 2004 were revisited. Of these,sites surveyed in 2005, mites were abundant at 25% of the sites, present to a lesser extent at 58% of the sites, and absent at 17% of the sites. The results demonstrate that A. anthocoptes is common on Canada thistle growing in these regions. It remains uncertain exactly how long A. anthocoptes has been present in eastern Colorado and Wyoming and western Nebraska, however, anecdotal evidence demonstrating a dramatic decline from 2002 to 2007 of Canada thistle at one Ft. Carson, CO site suggests that the mite may have been present in this area since 2002.