Host specificity of the Asian weevil, Rhinoncomimus latipes Korotyaev (Coleoptera: Curculionidae), a potential biological control agent of mile-a-minute weed, Polygonum perfoliatum L. (Polygonales: Polygonaceae)

The annual vine Polygonum perfoliatum L. (mile-a-minute weed) is an invasive weed in natural areas and has been targeted for biological control in the United States. Host specificity of the Asian weevil Rhinoncomimus latipes Korotyaev, a potential biological control agent of mile-a-minute weed, was evaluated in China using qualitative laboratory choice and no-choice tests on 28 plant species in 18 families outside of the Polygonaceae and on 21 species within the Polygonaceae. An open-field choice-test was also conducted in China. In addition, quantitative assessments of adult and larval no-choice tests and adult-choice tests were conducted in a quarantine laboratory in the United States on 23 species of Polygonaceae (including five also tested in China) and five species in three other plant families. Adult weevils did not eat any plant species in families outside of the Polygonaceae in choice or no-choice tests. In no-choice tests with Polygonaceae, adults fed and survived for up to 30 days on a few species in the tribes Persicarieae, Polygoneae, and Rumiceae, but females did not oviposit on any plant except P. perfoliatum, and in choice tests adults almost exclusively ate P. perfoliatum. Neonate larvae placed on alternative hosts did not survive longer than 36 h, while 80% of neonates placed on P. perfoliatum survived and completed development at least to pupation. Of all plant species tested, only P. perfoliatum fell within the physiological host range of R. latipes. Our tests indicate that R. latipes is a host specialist with minimal potential for non-target effects if released in the United States.