Location: Invasive Plant Research LaboratoryTitle: Host range validation, molecular identification, and release and establishment of a Chinese biotype of the Asian leaf beetle Lilioceris cheni (Coleoptera:Chrysomelidae:Criocerinae) for control of Dioscorea bulbifera L. in ...) Author
|Dray, F allen|
|Konstantinov, Alexander - Alex|
Submitted to: Biocontrol Science and Technology
Publication Type: Peer reviewed journal
Publication Acceptance Date: 3/26/2013
Publication Date: 7/17/2013
Citation: Center, T.D., Rayamajhi, M., Dray, F.A., Madeira, P.M., Witkus, G., Rohrig, E., Mattison, E., Lake, E., Smith, M., Zhang, J., Purcell, M., Konstantinov, A., Schmitz, D. Host range validation, molecular identification, and release and establishment of a Chinese biotype of the Asian leaf beetle Lilioceris cheni (Coleoptera:Chrysomelidae:Criocerinae) for control of Dioscorea bulbifera L. in the southern United States. Biocontrol Science and Technology. 23(7):735-755. 2013. Interpretive Summary: The air potato vine is a serious problem in many settings in the Southeast, but it is particularly problematic in parks and recreation areas where funds for control are limited. Although the vines die back every winter, they produce thousands of potato-like structures (bulbils) that sprout in the spring. A beetle found feeding on the leaves of this plant in Nepal was imported to quarantine facilities in Fort Lauderdale, tested, and found to feed only on air potato. Permission to release it was then granted by regulatory authorities. However, the laboratory colony died out due to the prolonged regulatory review. Hence, even though a release permit was obtained, there were no insects available to release and it was no longer possible to obtain them from Nepal. We therefore searched in southern China and found the same species as well as a second one that feeds on the overwintering “potatoes”. The leaf-feeding species was released and quickly caused massive defoliation of the vines, resulting in recovery of native plants. The other species is undergoing testing. The combination of the two, a leaf-feeder and a bulbil-feeder, should provided excellent control of this pernicious invader.
Technical Abstract: Dioscorea bulbifera, an Asian vine, is invasive in the southeastern USA. It rarely flowers but propagates from potato-like bulbils formed in leaf axils, which persist into the subsequent growing season. Lilioceris cheni Gressitt and Kimoto, a foliage-feeding beetle (Coleoptera: Chrysomelidae: Criocerinae) from Nepal, had been tested, proven to be a specialist and approved for release as a biological control agent. Regulatory delays, however, resulted in the demise of quarantine-held colonies and acquisition of new Nepalese stock proved untenable. Searches then undertaken in southern China resulted in the collection of over 300 similar beetles. Two Chinese Lilioceris species were identified: one confirmed to be L. cheni and the other identified as Lilioceris egena (Weise). Mitochondrial analysis revealed an exact DNA match between some Chinese and one of the two Nepalese c oxidase subunit I haplotypes and all Chinese L. cheni haplotypes clustered as a single species but the comingling of the two species aroused concerns over possible hybridisation. These concerns were allayed by nuclear D2 analysis showing the absence of dual parental sequences. Nonetheless, diligence was exercised to ensure that the Chinese strains were safe to release. Abridged host testing using critical test species verified specificity. Caged releases during autumn 2011 documented the ability of adult beetles to overwinter in south Florida despite a prolonged lack of foliage. Open releases the following year produced vigorous populations that caused extensive defoliation. Preliminary observations indicate that L. cheni now contributes to the control of D. bulbifera and the bulbil-feeding L. egen should complement these effects if its host range proves appropriate.