Kendall, Deborah M. Biocontrol Pest Management for Thistles in Wind Cave National Park and Biocontrol of Spurge in Jewel Cave National Monument. Annual Report; Proj. No.: WICA-R92-0200; Coop Agreement:CA 1268-1-9016; Work Order: FLC 8.

Abstract

Biological control of canada thistle, Cirsium arvense L. in Wind Cave National Park has focused on the release and monitoring of biocontrol agents. Biocontrol of canada thistle, C. arvense in Wind Cave National Park consisted of releases of Urophora cardul, the thistle gall fly and Ceutorhynchus litura, the root crown weevil were released at various sites according to the following program:
(1) 1,800 individuals of U. cardui, the thistle gall fly were released in eight sites in 1993.
(2) 3,00 individuals of C. litura, the root crown weevils released in 1993.

There were greater numbers of R. conicus than U. cardui in Norbeck Dam and NPS6 sites. On the other hand there were greater numbers of U. cardui than R. conicus. Habitat differences and age of canada thistle stands at the various sites influences the establishment of both biological control agents.

The percent coverage of canada thistle at Norbeck Dam was 48.16% and at Lone Pine was 42.67%.

A public service pamphlet describing life cycles, releases, monitoring and frequently asked questions regarding biocontrol was also produced.

Apthona nigriscutis, a biological control agent for the control of leafy spurge, Euphorbia esula L. was released at the following sites in Jewel Cave National Monument: 1,4,5,6 and 10. Percent coverage of leafy spurge at sites 1,2,5 and 10 was assessed as follows: 30.33%, 35.00%, 20.67% and 17.47%.