Beetle herding: Optimizing the biological control of the invasive air potato vine using attractive semiochemical lures

Purposeful manipulation of biological control programs, such as timed releases of biological control agents, can be ephemeral and difficult to expand into new areas impacted by the targeted invasive plant. Integration of chemical ecology through attractive semiochemical lures to aggregate biological control agents to un-colonized areas can help mitigate this challenge. The invasive air potato vine, Dioscorea bulbifera L., is native to Asia and Africa with invasive infestations in the southeastern United States, Hawai’i, and Puerto Rico. In 2011, a host specific biological control agent, Lilioceris cheni (Coleoptera: Chrysomelidae), was introduced to manage D. bulbifera. Synthetic and racemic blends of previously identified attractive herbivory induced plant volatiles (HIPVs), ocimene and farnesene, were first evaluated for antennal response through electroantennography, then deployed as potential attractive lures in field conditions. Electroantennogram results validated the ability of adult male and female L. cheni to detect the two compounds. When used in field conditions, adult L. cheni beetles showed increased response to plants with ocimene and farnesene lures compared to control plants. The chemically enhanced lures increased L. cheni adult densities on D. bulbifera plants in the field compared to control plants. Plants with higher densities of L. cheni had greater direct herbivore feeding damage and observed cupped leaves, indicating the presence of oviposition and future larval development. The information gathered in this study indicated that the use of attractant semiochemical lures to purposefully aggregate and direct movement of biological control agents can improve the efficacy of invasive plant biocontrol programs.