Thesis (M.S., Plant, Soil and Entomological Sciences) -- University of Idaho, 2016 | The weevil Mogulones crucifer Pallas (Coleoptera: Curculionidae) was released in Canada in 1997 for the biological control of the invasive plant Cynoglossum officinale L. The weevil was not permitted for release in the United States due to concerns over potential non-target attack on threatened plant species in the same family as C. officinale. To assess the risk posed by the weevil to native Boraginaceae plant species I 1) examined the behavioral response of the weevil to olfactory cues of C. officinale and selected native rare and threatened confamilial plants, and 2) characterized the headspace volatile profiles of plant species (GC/MS) and conducted electrophysiological experiments (GC-EAD) to measure the antennal responses of the weevil. Results indicate that during host finding, M. crucifer prefers C. officinale over all tested plants. I found that among non-target plants H. californica shared greatest number of compounds with C. officinale whereas A. occidentale shared least. I also identified six electrophysiologically active compounds in C. officinale that potentially contribute to this discrimination. Findings suggest that the weevil is unlikely to locate and therefore colonize any of the tested rare or threatened native confamilial species.