Arthropod biological control candidates of perennial pepperweed, an invasive weed native to Eurasia

The Eurasian plant, perennial pepperweed (Lepidium latifolium) is rapidly invading riparian habitats in the western United States, displacing native plants and altering food webs. Surveys in six countries in its native range, including China, Iran, and Turkey, have produced several arthropod biological control candidates. Preliminary host-specificity tests and observations of damage to the host plant indicate that two weevils (Melanobaris semistriata and Ceutorhynchus marginellus), one chloropid fly (Lasiosina deviata), and one eriophyoid mite (Metaculus lepidifolii) have promise as potential biological control agents, pending more intensive evaluations. In addition to continued testing on these candidate agents, we plan more field surveys in Turkey, Kazakhstan, and China to search for more candidates.