Biological control of Cabomba caroliniana in Australia
Cabomba caroliniana (Cabombaceae: EPPO List of Invasive Alien Plants) is an aquatic submerged ground rooted species native to Argentina and North America. In the EPPO region the species is established in Austria, France, Germany, Hungary, the Netherlands and the United Kingdom (England). The species is invasive in Australia, Canada, the Netherlands, Japan and parts of the USA. In the EU, C. caroliniana is listed as a species of Union concern (Regulation (EU) 1143/2014). A biological control programme has been initiated against the species in Australia using the aquatic weevil Hydrotimetes natans (Coleoptera: Curculionidae) as field surveys conducted in Argentina had identified it as a potential biological control agent. In Australia, host range testing showed that there were no non-target effects on Nymphaea, Victoria and Trithuria species. There was an indication of the possibility of lifecycle completion by H. natans on Brasenia schreberi (Cabombaceae), in choice and no-choice trials but this plant did not support a population in continued no-choice trials. Brasenia schreberi is native to Australia and is used as an aquarium plant. H. natans larvae inflicted greater damage than adults on C. caroliniana. First instar larvae fed on the leaves and the petiole and tunnelled through the main stem as they develop into later instars. The tunnelling causes significant damage to the foliage and stems. Based on the host range results, permission to release H. natans into Australian aquatic systems was granted in 2021 by the Australian Department of Agriculture, Water and the Environment.
Sources
Kumaran N, Vance TJ, Comben D, Dell Q, Oleiro MI, Ginalons CM, Walsh GC, Raghu S (2022) Hydrotimetes natans as a suitable biological control agent for the invasive weed Cabomba caroliniana. Biological Control. https://doi.org/10.1016/j.biocontrol.2022.104894