Objective:
Objective 1: Characterize the basic biology of target weeds, such as hoary cress, swallow-worts, medusahead, and guineagrass, and their natural enemies. Sub-objective 1.A. Characterize the genetic diversity and basic biology of target weeds and determine their regions of origin. Sub-objective 1.B. Conduct foreign exploration in Europe, Asia, and Africa for natural enemies of U.S. target weeds. Objective 2: Elucidate plant-natural enemy interactions and identify potential candidates for U.S. introduction. Sub-objective 2.A. Conduct preliminary host-specificity and effectiveness testing and facilitate U.S. introduction through prioritization and rearing of agents for target weeds, including, but not limited to giant reed, and swallow-worts. Sub-objective 2.B. Evaluate plant-insect interactions in evolutionary and ecological contexts – the role of visual ecology in host plant finding, selection and acceptance by candidate agents; evolution of differential host specificity in a biological control agent; efficacy of multiple vs. single weed biological control agents.

Approach:
We have adopted a “weed management pipeline” approach to our research that answers essential questions for successful classical biological control. A significant focus of this research is aimed at understanding the basic biology of target weeds, especially characterization of the genetic diversity of targets in their native and adventive ranges. This work will help identify the target’s region of origin, as well as the region(s) from which populations of the target have been introduced into the U.S. Foreign exploration for natural enemies will be conducted concurrently with these studies on target biology; this exploration will provide candidate biological control agents for the following studies. These investigations address target weed-natural enemy interactions, which will include host-specificity and effectiveness testing to facilitate introduction to the U.S., as well as experiments aimed at developing a mechanistic understanding of the evolutionary, ecological, and physiological factors of plant-insect interactions relevant to weed biological control. Successful control of a target weed usually requires decades of research effort, and the research proposed here will be an important step towards ecologically-rational management of some of the most important invasive weeds in the U.S.