Objective:
To discover and evaluate new natural enemies of selected weeds of European origin presently invasive in the U.S.

Approach:
Explorations will be conducted in Europe for new natural enemies and new geographic biotypes of known natural enemies of the following weeds: yellow starthistle, spotted knapweed, Scotch thistle, Dyer's woad, perennial pepperweed, rush skeletonweed, and swallow-worts. Promising agents will be colonized, potential non-target plants will be grown, and the agents tested for damage to the target weed as well as appropriate related non-target plants. For perennial pepperweed, geographic populations of the weed, plus selected agents will be collected and provided to EBCL for DNA analysis. Extensive collections of swallow-worts will be made in cooperation with scientists from Russia and provided to EBCL for DNA analysis to determine the European location of biotypes now invasive in the U.S.; upon identifying sites of origin, natural enemies will be surveyed, promising species colonized and target and non-target tests will be performed. Use standard systematics approaches to characterize insect agents for weeds. All activities should be designed as suitable for publication in collaboration with appropriate EBCL and domestic cooperators. BBCA will provide reports of progress annually or as requested by ARS. All programmatic changes must be approved in advance by NPS.