Location: Invasive Plant Research LaboratoryTitle: Biological control of Hydrilla verticillata (L.f.) Royle (Hydrocharitaceae), a submersed aquatic macrophyte) Author
Submitted to: Meeting Abstract
Publication Type: Proceedings
Publication Acceptance Date: 7/14/2009
Publication Date: 10/1/2010
Publication URL: www.insectscience.org/10.166/abstract102.html
Citation: Ding, J., Zhang, J., Wheeler, G.S., Purcell, M., Center, T.D. 2010. Biological control of Hydrilla verticillata (L.f.) Royle (Hydrocharitaceae), a submersed aquatic macrophyte. Meeting Abstract. Vol. 10, Article 166. Interpretive Summary: Hydrilla verticillata is among the worst weeds in streams, rivers, and lakes in the southern US. This species forms dense stands, crowds out native vegetation, impedes navigation, and makes water management problematic. Hydrilla is controlled mainly with chemical herbicides; however both mechanical removal and biological agents (e.g. fish and insects) play some role. Since the discovery of herbicide resistance in hydrilla populations in Florida, alternative forms of control, especially biological control, have become a high priority. Surveys for insects that feed on hydrilla in China discovered several new species of beetles, a leaf beetle Macroplea japana and three species of weevils in the Bagous genus. To date none of these were found to be sufficiently specific for field release in the US, however additional testing and surveys continue.
Technical Abstract: Survey and testing of potential Hydrilla verticillata L.f. Royle biological control agents has been conducted in China from 2006 to the present. Several new species of insects have been discovered and tested to determine their suitability for release in the US to control this invasive weed. The beetle Macroplea japana (Jacoby) (Coleoptera: Chrysomelidae) was discovered in South China and was found feeding on nine host species including Hydrilla verticillata, Vallisneria spiralis, Potamogeton malaianus, Potamogeton maackianus, Potamogeton perfoliatus, Ottelia acuminata, Myriophyllum verticillatum, Nymphoides peltatum, and Alopecurus aequalis. Additional new species of Bagous weevils were discovered including B. chinensis and two undescribed new species, Bagous sp 1 and Bagous sp 2. Thus far, only B. chinensis and Bagous sp 1 have been tested and found to have a broad host range feeding on several species of Chinese aquatic plant species. Considering the wide host range of M. japana, B. chinensis, and Bagous sp1 it is unlikely that these species will be used as a biological control agent for hydrilla. However the colonization and testing of Bagous sp2 is underway during 2011. Furthermore, surveys are ongoing throughout China searching for additional herbivore species of this invasive weed.