Herbivory by the biocontrol agent Lilioceris cheni suppresses propagule production and smothering ability of the invasive vine Dioscorea bulbifera

Authors: Rayamajhi, Min; ROHRIG, ERIC - Florida Department Of Agriculture And Consumer Services; Leidi, Jorge; KERR, CHRISTOPHER - Florida Department Of Agriculture And Consumer Services; SALCEDO, EDUARDO - Miami-Dade County Parks, Recreation And Open Spaces Department; POFFENBERGER, RYAN - Florida Department Of Agriculture And Consumer Services; Smith, Melissa; Lake, Ellen; Dray, F Allen; Pratt, Paul; Tipping, Philip; Center, Ted

Submitted to: Biological Control
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/4/2018
Publication Date: 3/1/2019
Citation: Rayamajhi, M.B., Rohrig, E., Leidi, J.G., Kerr, C., Salcedo, E., Poffenberger, R., Smith, M., Lake, E.C., Dray Jr, F.A., Pratt, P.D., Tipping, P.W., Center, T.D. 2019. Herbivory by the biocontrol agent Lilioceris cheni suppresses propagule production and smothering ability of the invasive vine Dioscorea bulbifera. Biological Control. 130:1-8. https://doi.org/10.1016/j.biocontrol.2018.12.001.
DOI: https://doi.org/10.1016/j.biocontrol.2018.12.001

Interpretive Summary: Expanding populations of air potato vine, a trellising invasive plant of Afro-Asian provenance, have widely established in the southeastern United States. Clambering habit enables this weed to grow over, cover, smother and displace native vegetation while producing vast quantities of vegetative propagules (bulbils), and reduce biodiversity in various upland ecosystems of Florida. We hypothesized that importation of specialized herbivores from the native range of air potato and deployment in adventive range would suppress its invasive tendencies and thereby hinder the ability to overtop native vegetation and suppress propagule production. These hypotheses were tested by deploying a air potato foliage-feeding beetle imported from Nepal and China. We established beetle restricted (insecticide treated) and unrestricted (beetle inoculated) treatments at five research sites in Florida. Dioscorea bulbifera cover, L. cheni population density, and herbivore-induced damage to vines were documented at 6-wk intervals, and bulbil density and biomass annually, for 5 years. Results at beetle-unrestricted sites revealed significantly higher beetle feeding damage on air potato vines causing reduced vine cover (smothering effects) on native vegetation, and decreased bulbil density and biomass, as compared to beetle-restricted treatments. Both treatments showed similar trends in terms of effects on vine cover, and bulbil density but individual bulbil biomass remained unchanged in restricted treatment. Spillover of beetle populations from unrestricted into restricted treatment after exhaustion of air potato vines resulted in coalescing effects between treatments. Nonetheless, our data clearly demonstrated the ability of air potato foliage-feeding beetle to suppress the invasiveness of air potato vines in their adventive ranges.

Technical Abstract: Expanding populations of Dioscorea bulbifera, a trellising invasive vine of Afro-Asian provenance, have widely established in the southeastern United States. Clambering habit enables this weed to grow over, cover, smother and displace native vegetation while producing vast quantities of vegetative propagules (bulbils), and reduce biodiversity in various upland ecosystems of Florida. We hypothesized that importation of specialized herbivores from the native range of D. bulbifera and deployment in adventive range would suppress its invasive tendencies and thereby hinder the ability to overtop native vegetation and suppress propagule production. These hypotheses were tested by deploying Lilioceris cheni, a foliage-feeding beetle imported from Nepal and China. We established beetle restricted (insecticide treated) and unrestricted (beetle inoculated) treatments at five research sites in Florida. Dioscorea bulbifera cover, L. cheni population density, and herbivore-induced damage to vines were documented at 6-wk intervals, and bulbil density and biomass annually, for 5 years. Results at beetle-unrestricted sites revealed significantly higher L. cheni feeding damage on D. bulbifera causing reduced vine cover (smothering effects) on native vegetation, and decreased bulbil density and biomass, as compared to beetle-restricted treatments. However, both treatments showed similar trends in terms of effects on vine cover, and bulbil density but individual bulbil biomass remained unchanged in restricted treatment. Spillover of L. cheni populations from beetle unrestricted into restricted treatment after exhaustion of D. bulbifera vines resulted in coalescing effects between treatments. Nonetheless, our data clearly demonstrated the ability of L. cheni to suppress the invasive attributes of D. bulbifera in its adventive range.